- ID:
- ivo://CDS.VizieR/J/ApJ/699/66
- Title:
- Abundances in two Galactic bulge stars
- Short Name:
- J/ApJ/699/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present abundance analyses based on high dispersion and high signal-to-noise ratio Magellan spectra of two highly microlensed Galactic bulge stars in the region of the main-sequence turnoff with T_eff_~5650K. We find that MOA-2008-BLG-310S has [Fe/H]^8^=+0.41+/-0.09dex and MOA-2008-BLG-311S has +0.26+/-0.09dex. The abundance ratios for the ~20 elements for which features could be detected in the spectra of each of the two stars follow the trends with [Fe/H] found among samples of bulge giants. Combining these two bulge dwarfs with the results from previous abundance analysis of four other Galactic bulge turnoff region stars, all highly magnified by microlensing, gives a mean [Fe/H] of +0.29dex. This implies that there is an inconsistency between the Fe-metallicity distribution of the microlensed bulge dwarfs and that derived by the many previous estimates based on surveys of cool, luminous bulge giants, which have mean [Fe/H]~-0.1dex.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/293/75
- Title:
- Abundances in zeta Scl open cluster
- Short Name:
- J/A+A/293/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/398/1121
- Title:
- Abundances of A-F stars
- Short Name:
- J/A+A/398/1121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Fundamental parameters and abundances of 140 A and F-type stars are presented. The barycentric Julian dates and signal-to-noise ratios are also given.
- ID:
- ivo://CDS.VizieR/J/MNRAS/376/361
- Title:
- Abundances of 5 Ap/Bp stars of NGC 6475
- Short Name:
- J/MNRAS/376/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The connection between age, rotation and chemical abundance of magnetic Ap stars is poorly understood. Using open clusters, we are able to study samples of stars that are both coeval and co-environmental. By determining rotation and chemical abundance for Ap star members of clusters with various ages, the variations of these properties as a function of age and environment can be derived. All four probable Ap star members of the open cluster NGC 6475, as well as one normal late B star, were studied using detailed spectrum synthesis of high-resolution UVES-POP spectra. Probable cluster membership was confirmed for all five stars; however, chemical abundance anomalies only appear to be present in spectra of three. Projected rotational velocity and chemical abundances for 21 elements ranging from C to Eu are presented for the five stars. In the three peculiar stars, we find overabundances of Si, Cr, Mn, Fe and rare earths, such as Nd, characteristic of Ap stars. The set of chemically peculiar stars show fairly homogeneous abundance tables, however, notable differences exist for a few elements. There also exist appreciable differences in the vsini and main-sequence evolutionary stage of the chemically peculiar stars. This may hint at the underlying processes giving rise to the observed abundance anomalies. With this first detailed study of chemical abundances of a complete sample of magnetic Ap/Bp stars in an open cluster, we have initiated an exploration of the environmental and evolutionary influence on chemical peculiarity.
- ID:
- ivo://CDS.VizieR/J/ApJ/636/821
- Title:
- Abundances of Baade's Window K giants
- Short Name:
- J/ApJ/636/821
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of a new abundance survey of the Milky Way bulge based on Keck HIRES spectra of 27 K giants in the Baade's Window (l=1{deg},b=-4{deg}) field. The spectral data used in this study are of much higher resolution and signal-to-noise ratio than previous optical studies of Galactic bulge stars. The [Fe/H] values of our stars, which range between 1.29 and +0.51, were used to recalibrate large low-resolution surveys of bulge stars. Our best value for the mean [Fe/H] of the bulge is -0.10+/-0.04. This mean value is similar to the mean metallicity of the local disk and indicates that there cannot be a strong metallicity gradient inside the solar circle. The metallicity distribution of stars confirms that the bulge does not suffer from the so-called G dwarf problem. This paper also details the new abundance techniques necessary to analyze very metal-rich K giants, including a new Fe line list and regions of low blanketing for continuum identification.
- ID:
- ivo://CDS.VizieR/J/A+A/454/895
- Title:
- Abundances of 26 barium stars. I.
- Short Name:
- J/A+A/454/895
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The abundances for Na, Al, alpha-, iron-peak, s-, and r-elements have been derived by using spectrum synthesis for a sample of 26 barium stars, including dwarf barium stars. High-resolution spectra were obtained with the FEROS spectrograph at the ESO-1.52m Telescope, along with photometric data with Fotrap at the Zeiss telescope at the LNA.
- ID:
- ivo://CDS.VizieR/J/A+A/454/917
- Title:
- Abundances of 26 barium stars. II.
- Short Name:
- J/A+A/454/917
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this work is to quantify the contributions of the s-, r-, and p-processes for the total abundance of heavy elements from abundances derived for a sample of 26 barium stars. The abundances of the sample stars were compared to those of normal stars, thus identifying the fraction relative to the main component of the s-process s. The fittings of the sigmaN curves (neutron-capture cross-section times abundance, plotted against atomic mass number) for the sample stars suggest that the material from the companion asymptotic giant branch star had approximately the solar isotopic composition as concerns fractions of abundances relative to the s-process main component.
- ID:
- ivo://CDS.VizieR/J/A+A/434/235
- Title:
- Abundances of BHB stars in NGC 1904
- Short Name:
- J/A+A/434/235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The abundance measurements are based on high-resolution optical spectroscopical data, obtained during 2 observing runs with the Ultraviolet and Visual Echelle Spectrograph mounted on Kueyen (Very Large Telescope UT2). Ten target stars in the extended blue horizontal branch of the Galactic globular cluster NGC 1904 (M79) have been analysed.
- ID:
- ivo://CDS.VizieR/J/ApJ/864/43
- Title:
- Abundances of 3 bright extremely metal-poor giants
- Short Name:
- J/ApJ/864/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present detailed chemical abundances of three new bright (V~11), extremely metal-poor ([Fe/H]~-3.0), r-process-enhanced halo red giants based on high-resolution, high-S/N Magellan/MIKE spectra. We measured abundances for 20-25 neutron-capture elements in each of our stars. J1432-4125 is among the most r-process-rich r-II stars, with [Eu/Fe]=+1.44+/-0.11. J2005-3057 is an r-I star with [Eu/Fe]=+0.94+/-0.07. J0858-0809 has [Eu/Fe]=+0.23+/-0.05 and exhibits a carbon abundance corrected for an evolutionary status of [C/Fe]_corr_=+0.76, thus adding to the small number of known carbon-enhanced r-process stars. All three stars show remarkable agreement with the scaled solar r-process pattern for elements above Ba, consistent with enrichment of the birth gas cloud by a neutron star merger. The abundances for Sr, Y, and Zr, however, deviate from the scaled solar pattern. This indicates that more than one distinct r-process site might be responsible for the observed neutron-capture element abundance pattern. Thorium was detected in J1432-4125 and J2005-3057. Age estimates for J1432-4125 and J2005-3057 were adopted from one of two sets of initial production ratios each by assuming the stars are old. This yielded individual ages of 12+/-6Gyr and 10+/-6Gyr, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/797/13
- Title:
- Abundances of bright metal-poor stars
- Short Name:
- J/ApJ/797/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The chemical abundances of large samples of extremely metal-poor (EMP) stars can be used to investigate metal-free stellar populations, supernovae, and nucleosynthesis as well as the formation and galactic chemical evolution of the Milky Way and its progenitor halos. However, current progress on the study of EMP stars is being limited by their faint apparent magnitudes. The acquisition of high signal-to-noise spectra for faint EMP stars requires a major telescope time commitment, making the construction of large samples of EMP star abundances prohibitively expensive. We have developed a new, efficient selection that uses only public, all-sky APASS optical, 2MASS near-infrared, and WISE mid-infrared photometry to identify bright metal-poor star candidates through their lack of molecular absorption near 4.6 microns.
- ID:
- ivo://CDS.VizieR/J/AJ/148/67
- Title:
- Abundances of 156 bulge red giants
- Short Name:
- J/AJ/148/67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present radial velocities and chemical abundances of O, Na, Mg, Al, Si, Ca, Cr, Fe, Co, Ni, and Cu for a sample of 156 red giant branch stars in two Galactic bulge fields centered near (l,b)=(+5.25,-3.02) and (0,-12). The (+5.25,-3.02) field also includes observations of the bulge globular cluster NGC 6553. The results are based on high-resolution (R~20000), high signal-to-noise ration (S/N>~70) FLAMES-GIRAFFE spectra obtained through the European Southern Observatory archive. However, we only selected a subset of the original observations that included spectra with both high S/N and that did not show strong TiO absorption bands. This work extends previous analyses of this data set beyond Fe and the {alpha}-elements Mg, Si, Ca, and Ti. While we find reasonable agreement with past work, the data presented here indicate that the bulge may exhibit a different chemical composition than the local thick disk, especially at [Fe/H]>~-0.5. In particular, the bulge [{alpha}/Fe] ratios may remain enhanced to a slightly higher [Fe/H] than the thick disk, and the Fe-peak elements Co, Ni, and Cu appear enhanced compared to the disk. There is also some evidence that the [Na/Fe] (but not [Al/Fe]) trends between the bulge and local disk may be different at low and high metallicity. We also find that the velocity dispersion decreases as a function of increasing [Fe/H] for both fields, and do not detect any significant cold, high-velocity populations. A comparison with chemical enrichment models indicates that a significant fraction of hypernovae may be required to explain the bulge abundance trends, and that initial mass functions that are steep, top-heavy (and do not include strong outflow), or truncated to avoid including contributions from stars >40M_{sun}_ are ruled out, in particular because of disagreement with the Fe-peak abundance data. For most elements, the NGC 6553 stars exhibit abundance trends nearly identical to comparable metallicity bulge field stars. However, the star-to-star scatter and mean [Na/Fe] ratios appear higher in the cluster, perhaps indicating additional self-enrichment.
- ID:
- ivo://CDS.VizieR/J/A+A/530/A54
- Title:
- Abundances of 650 bulge red giants
- Short Name:
- J/A+A/530/A54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of the [alpha/Fe] abundance ratios for a large number of stars at several locations in the Milky Way bulge with the aim of constraining its formation scenario. We obtained FLAMES-GIRAFFE spectra (R=22500) at the ESO Very Large Telescope for 650 bulge red giant branch (RGB) stars and performed spectral synthesis to measure Mg, Ca, Ti, and Si abundances. This sample is composed of 474 giant stars observed in 3 fields along the minor axis of the Galactic bulge and at latitudes b=-4{deg}, b=-6{deg}, b=-12{deg}. Another 176 stars belong to a field containing the globular cluster NGC 6553, located at b=-3{deg} and 5{deg} away from the other three fields along the major axis.
- ID:
- ivo://CDS.VizieR/J/A+A/548/A34
- Title:
- Abundances of carbon-enhanced metal-poor stars
- Short Name:
- J/A+A/548/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed study of Carbon-Enhanced Metal-Poor (CEMP) stars, based on high-resolution spectroscopic observations of a sample of 18 stars. The stellar spectra for this sample were obtained at the 4.2m William Herschel Telescope (WHT) in 2001 and 2002, using the Utrecht Echelle Spectrograph (UES), at a resolving power R~52000 and S/N~40, covering the wavelength range {lambda}-{lambda}3700-5700{AA}. The atmospheric parameters determined for this sample indicate temperatures ranging from 4750K to 7100K, log g from 1.5 to 4.3, and metallicities -3.0<=[Fe/H]<=-1.7. Elemental abundances for C, Na, Mg, Sc, Ti, Cr, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, Eu, Gd, Dy are determined. Abundances for an additional 109 stars were taken from the literature and combined with the data of our sample. The literature sample reveals a lack of reliable abundance estimates for species that might be associated with the r-process elements for about 67% of CEMP stars, preventing a complete understanding of this class of stars, since [Ba/Eu] ratios are used to classify them. Although eight stars in our observed sample are also found in the literature sample, Eu abundances or limits are determined for four of these stars for the first time. From the observed correlations between C, Ba, and Eu, we argue that the CEMP-r/s class has the same astronomical origin as CEMP-s stars, highlighting the need for a more complete understanding of Eu production.
- ID:
- ivo://CDS.VizieR/J/ApJ/658/367
- Title:
- Abundances of carbon stars in Galactic halo
- Short Name:
- J/ApJ/658/367
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is known that the carbon-enhanced, extremely metal-poor (CEMP) stars constitute a substantial proportion of the extremely metal-poor (EMP) stars of the Galactic halo, and a by far larger proportion than CH stars among Population II stars. We investigate their origin by taking into account an additional evolutionary path to the surface carbon enrichment, triggered by hydrogen engulfment by the helium flash convection, in EMP stars with [Fe/H]<~-2.5. This process is distinct from the third dredge-up operating in more metal-rich stars and in EMP stars. In binary systems of EMP stars, the secondary stars become CEMP stars through mass transfer from the low- and intermediate- mass primary stars that have developed the surface carbon enhancement. Our binary scenario can predict the variations in the abundances not only for carbon but also for nitrogen and s-process elements and can reasonably explain the observed properties such as the stellar distributions of the carbon abundances, the binary periods, and the evolutionary stages.
- ID:
- ivo://CDS.VizieR/J/A+A/579/A28
- Title:
- Abundances of 3 CEMP stars
- Short Name:
- J/A+A/579/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the course of the TOPoS (Turn Off Primordial Stars) survey, aimed at discovering the lowest metallicity stars, we have found several carbon-enhanced metal-poor (CEMP) stars. These stars are very common among the stars of extremely low metallicity and provide important clues to the star formation processes. We here present our analysis of six CEMP stars. We want to provide the most complete chemical inventory for these six stars in order to constrain the nucleosynthesis processes responsible for the abundance patterns.
- ID:
- ivo://CDS.VizieR/J/AJ/132/902
- Title:
- Abundances of 54 Cepheids
- Short Name:
- J/AJ/132/902
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper reports on the spectroscopic investigation of 54 Cepheids, deriving parameters and abundances. These Cepheids extend previous samples by about 35% in number and increase the amount of the Galactic disk coverage, especially in the direction of l~120{deg}. We find that there exists in the Galactic disk at that longitude and at a solar distance of about 3-4kpc a region that has enhanced abundances, <[Fe/H]>~+0.2, with respect to the local region. A simple linear fit to all Cepheid data now extant yields a gradient d[Fe/H]/dR=-0.068+/-0.003dex/kpc. After consideration of the spatial abundance inhomogeneities in the sample, we conclude that the best current estimate of the overall gradient is d[Fe/H]/dR=-0.06dex/kpc.
- ID:
- ivo://CDS.VizieR/J/AJ/128/343
- Title:
- Abundances of 10 Cepheids
- Short Name:
- J/AJ/128/343
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a detailed multiphase spectroscopic analysis of 10 classical Cepheids with pulsation periods between 6 and 10 days. For each star, we have derived phased values of effective temperature, surface gravity, microturbulent velocity, and elemental abundances. We show that the elemental abundance results for intermediate-period Cepheids are consistent for all pulsational phases.
- ID:
- ivo://CDS.VizieR/J/MNRAS/420/1590
- Title:
- Abundances of classical Cepheids
- Short Name:
- J/MNRAS/420/1590
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We propose a statistical method for decomposition of contributions to iron production from various sources: Type II supernovae and the subpopulations of Type Ia supernovae, prompt (their progenitors are short-lived stars with ages lower than >100Myr) and tardy (their progenitors are long-lived stars with ages >100Myr). To do that, we develop a theory of oxygen and iron synthesis that takes into account the influence of the spiral arms on the amount of the above elements synthesized by both Type II supernovae and prompt Type Ia supernovae. In the framework of the theory, we processed statistically the new, more precise, observational data on Cepheid abundances, which, as is well known, demonstrate non-trivial radial distributions of oxygen and iron in the Galactic disc with bends in the gradients.
- ID:
- ivo://CDS.VizieR/J/A+A/345/430
- Title:
- Abundances of 6 cool supergiants in NGC 330
- Short Name:
- J/A+A/345/430
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 330 is the brightest SMC young cluster and contains many bright supergiants. This cluster has aroused special interest, since the earlier abundance determinations indicated an abundance lower by a factor 5 than in the SMC field young population. In this Paper we analyse high resolution spectra of 6 cool supergiants in NGC 330, and compare in an homogeneous way, the metallicity and abundance ratios of various elements in NGC 330 and in the field of the SMC. The following Table is the Apendix to this Paper, giving the line list used in the analysis, together with the measured equivalent width and the derived abundance for each of the 6 stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/737/L32
- Title:
- Abundances of 16 Cyg A and B
- Short Name:
- J/ApJ/737/L32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of a detailed abundance analysis of the solar twins 16 Cyg A and 16 Cyg B based on high-resolution, high signal-to-noise ratio echelle spectroscopy are presented. 16 Cyg B is known to host a giant planet while no planets have yet been detected around 16 Cyg A. Stellar parameters are derived directly from our high-quality spectra, and the stars are found to be physically similar, with {Delta}T_eff_=+43K, {Delta}logg=-0.02dex, and {Delta}{xi}=+0.10km/s (in the sense of A-B), consistent with previous findings. Abundances of 15 elements are derived and are found to be indistinguishable between the two stars. The abundances of each element differ by <=0.026dex, and the mean difference is +0.003+/-0.015({sigma}) dex. Aside from Li, which has been previously shown to be depleted by a factor of at least 4.5 in 16 Cyg B relative to 16 Cyg A, the two stars appear to be chemically identical. The abundances of each star demonstrate a positive correlation with the condensation temperature of the elements (T_c_); the slopes of the trends are also indistinguishable. In accordance with recent suggestions, the positive slopes of the [m/H]-T_c_ relations may imply that terrestrial planets have not formed around either 16 Cyg A or 16 Cyg B.
- ID:
- ivo://CDS.VizieR/J/A+A/625/A141
- Title:
- Abundances of disk and bulge giants
- Short Name:
- J/A+A/625/A141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation and evolution of the Galactic bulge and the Milky Way is still a debated subject. Observations of the X-shaped bulge, cylindrical stellar motions, and the presumed existence of a fraction of young stars in the bulge have suggested that it formed through secular evolution of the disk and not through gas dissipation and/or mergers, as thought previously. Our goal was to measure the abundances of six iron-peak elements (Sc, V, Cr, Mn, Co, and Ni) in the local thin and thick disks and in the bulge. These abundances can provide additional observational constraints for Galaxy formation and chemical evolution models, and help us to understand whether the bulge has emerged from the thick disk or not. We use high-resolution optical spectra of 291 K giants in the local disk mostly obtained by the FIES at NOT (signal-to-noise ratio (S/N) of 80-100) and 45K giants in the bulge obtained by the UVES/FLAMES at VLT (S/N of 10-80). The abundances are measured using Spectroscopy Made Easy (SME). Additionally, we apply non-local thermodynamic equilibrium (NLTE) corrections to the ratios [Mn/Fe] and [Co/Fe]. The thin and thick disks were separated according to their metallicity, [Ti/Fe], as well as proper motions and the radial velocities from Gaia DR2. The trend of [V/Fe] vs. [Fe/H] shows a separation between the disk components, being more enhanced in the thick disk. Similarly, the [Co/Fe] vs. [Fe/H] trend shows a hint of an enhancement in the local thick disk. The trends of V and Co in the bulge appear to be even more enhanced, although within the uncertainties. The decreasing value of [Sc/Fe] with increasing metallicity is observed in all the components, while our [Mn/Fe] value steadily increases with increasing metallicity in the local disk and the bulge instead. For Cr and Ni we find a flat trend following iron for the whole metallicity range in the disk and the bulge. The ratio of [Ni/Fe] appears slightly overabundant in the thick disk and the bulge compared to the thin disk, although the difference is minor. The somewhat enhanced ratios of [V/Fe] and [Co/Fe] observed in the bulge suggest that the local thick disk and the bulge might have experienced different chemical enrichment and evolutionary paths. However, we are unable to predict the exact evolutionary path of the bulge solely based on these observations. Galactic chemical evolution models could, on the other hand, allow us to predict them using these results.
- ID:
- ivo://CDS.VizieR/J/A+A/598/A100
- Title:
- Abundances of disk giants: O, Mg, Ca and Ti
- Short Name:
- J/A+A/598/A100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galactic bulge is an intriguing and significant part of our Galaxy, but it is hard to observe because it is both distant and covered by dust in the disk. Therefore, there are not many high-resolution optical spectra of bulge stars with large wavelength coverage, whose determined abundances can be compared with nearby, similarly analyzed stellar samples. We aim to determine the diagnostically important alpha elements of a sample of bulge giants using high-resolution optical spectra with large wavelength coverage. The abundances found are compared to similarly derived abundances from similar spectra of similar stars in the local thin and thick disks. In this first paper we focus on the solar neighborhood reference sample. We used spectral synthesis to derive the stellar parameters as well as the elemental abundances of both the local and bulge samples of giants. We took special care to benchmark our method of determining stellar parameters against independent measurements of effective temperatures from angular diameter measurements and surface gravities from asteroseismology. In this first paper we present the method used to determine the stellar parameters and elemental abundances, evaluate them, and present the results for our local disk sample of 291 giants. When comparing our determined spectroscopic temperatures to those derived from angular diameter measurements, we reproduce these with a systematic difference of +10K and a standard deviation of 53K. The spectroscopic gravities reproduce those determined from asteroseismology with a systematic offset of +0.10dex and a standard deviation of 0.12dex. When it comes to the abundance trends, our sample of local disk giants closely follows trends found in other works analyzing solar neighborhood dwarfs, showing that the much brighter giant stars are as good abundance probes as the often used dwarfs.
- ID:
- ivo://CDS.VizieR/J/A+A/423/867
- Title:
- Abundances of distant luminous infrared galaxies
- Short Name:
- J/A+A/423/867
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One hundred and five 15{mu}m-selected objects in three ISO (Infrared Space Observatory) deep survey fields (CFRS 3h, UDSR and UDSF) are studied on the basis of their high-quality optical spectra with resolution R>1000 from VLT/FORS2. ~92 objects (88%) have secure redshifts, ranging from 0 to 1.16 with a median value of z_med_=0.587.
- ID:
- ivo://CDS.VizieR/J/A+A/515/A28
- Title:
- Abundances of dwarfs and giants in 2 open clusters
- Short Name:
- J/A+A/515/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It has been suggested that the classical chemical analysis may be affected by systematic errors that would introduce abundance differences between dwarfs and giants. For some elements, the abundance difference could be real. We address the issue by observing 2 solar-type dwarfs in NGC 5822 and 3 in IC 4756, and comparing their composition with that of 3 giants in either of the aforementioned clusters. We determine iron abundance and stellar parameters for dwarf stars. Then, abundances of calcium, sodium, nickel, titanium, aluminium, chromium, and silicon were determined for both giants and dwarfs. The standard equivalent width analysis was performed differentially with respect to the Sun. We find an iron abundance for dwarf stars equal to solar to within the margins of error for IC 4756, and slightly above for NGC 5822 ([Fe/H]=0.01 and 0.05dex respectively). We show that, for sodium, silicon, and titanium, abundances of giants are significantly higher than those of the dwarfs of the same cluster (about 0.15, 0.15, and 0.35dex). Other elements may also undergo some enhanced, but all within 0.1dex.
- ID:
- ivo://CDS.VizieR/J/ApJ/878/99
- Title:
- Abundances of dwarfs & giants in NGC752 with HIRES
- Short Name:
- J/ApJ/878/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The chemical composition of stars in open clusters provides the best information on the chemical evolution of stars via comparison of main-sequence stars with evolved giants. This is a case study of the abundances in the dwarfs and giants in the old open cluster NGC 752. It is also a pilot program for automated abundance determinations, including equivalent-width measurements, stellar parameter determinations, and abundance analysis. We have found abundances of 31 element-ion combinations in 23 dwarfs and six giants. The mean cluster abundance of Fe is solar with [Fe/H]=-0.01+/-0.06 with no significant difference between the dwarfs and giants. We find that the cluster abundances of other elements, including alpha-elements, to be at or slightly above solar levels. We find some evidence for CNO processing in the spectra of the giants. The enhancement of Na in giants indicates that the NeNa cycle has occurred. The abundances of Mg and Al are similar in the dwarfs and giants, indicating that the hotter MgAl cycle has not occurred. We find no evidence of s-process enhancements in the abundances of heavy elements in the giants.
- ID:
- ivo://CDS.VizieR/J/A+A/448/955
- Title:
- Abundances of emission galaxies in SDSS-DR3
- Short Name:
- J/A+A/448/955
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have re-evaluated empirical expressions for the abundance determination of N, O, Ne, S, Cl, Ar and Fe taking into account the latest atomic data and constructing an appropriate grid of photoionization models with state-of-the art model atmospheres. Using these expressions we have derived heavy element abundances in the ~310 emission-line galaxies from the Data Release 3 of the Sloan Digital Sky Survey (SDSS, <III/241>) with an observed Hbeta flux F(Hbeta)>10^-14^erg/s/cm^2^ and for which the [O III] 4363 emission line was detected at least at a 2sigma level, allowing abundance determination by direct methods. The oxygen abundance 12+logO/H of the SDSS galaxies lies in the range from ~7.1 (Z_{sun}_/30) to ~8.5 (0.7Z_{sun}_). The SDSS sample is merged with a sample of 109 blue compact dwarf (BCD) galaxies with high quality spectra, which contains extremely low-metallicity objects. We use the merged sample to study the abundance patterns of low-metallicity emission-line galaxies. We find that extremely metal-poor galaxies (12+logO/H<7.6, i.e. Z<Z_{sun}_/12) are rare in the SDSS sample. The alpha element to oxygen abundance ratios do not show any significant trends with oxygen abundance, in agreement with previous studies, except for a slight increase of Ne/O with increasing metallicity, which we interpret as due to a moderate depletion of O onto grains in the most metal-rich galaxies. The Fe/O abundance ratio is smaller than the solar value, by up to 1 dex at the high metallicity end. We also find that Fe/O increases with decreasing Hbeta equivalent width EW(Hbeta). We interpret this as a sign of strong depletion onto dust grains, and gradual destruction of those grains on a time scale of a few Myr. All the galaxies are found to have logN/O>-1.6, implying that they have a different nature than the subsample of high-redshift damped Lyalpha systems with log N/O of ~-2.3 and that their ages are larger than 100-300Myr. We confirm the apparent increase in N/O with decreasing EW(Hbeta), already shown in previous studies, and explain it as the signature of gradual nitrogen ejection by massive stars from the most recent starburst.
- ID:
- ivo://CDS.VizieR/J/A+A/554/A84
- Title:
- Abundances of evolved stars
- Short Name:
- J/A+A/554/A84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Currently, the core accretion model has its strongest observational evidence on the chemical signature of mostly main sequence stars with planets. We aim to test whether the well-established correlation between the metallicity of the star and the presence of giant planets found for main sequence stars still holds for the evolved and generally more massive giant and subgiant stars. Although several attempts have been made so far, the results are not conclusive since they are based on small or inhomogeneous samples. We determine in a homogeneous way the metallicity and individual abundances of a large sample of evolved stars, with and without known planetary companions, and discuss their metallicity distribution and trends. Our methodology is based on the analysis of high-resolution echelle spectra (R~67000) from 2-3 meter class telescopes. It includes the calculation of the fundamental stellar parameters (effective temperature, surface gravity, microturbulent velocity, and metallicity) by applying iron ionisation and excitation equilibrium conditions to several isolated FeI and FeII lines, as well as, calculating individual abundances of different elements such as Na, Mg, Si, Ca, Ti, Cr, Co, or Ni.
- ID:
- ivo://CDS.VizieR/J/ApJ/865/44
- Title:
- Abundances of evolved stars from IGRINS. I.
- Short Name:
- J/ApJ/865/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have derived elemental abundances of three field red horizontal branch stars using high-resolution (R~45000), high signal-to-noise ratio (S/N>~200) H- and K-band spectra obtained with the Immersion Grating Infrared Spectrograph (IGRINS). We have determined the abundances of 21 elements, including {alpha} (Mg, Si, Ca, S), odd-Z (Na, Al, P, K), Fe-group (Sc, Ti, Cr, Co, Ni), neutron-capture (Ce, Nd, Yb), CNO-group elements. S, P, and K are determined for the first time in these stars. H- and K-band spectra provide a substantial number of S I lines, which potentially can lead to a more robust exploration of the role of sulfur in the cosmochemical evolution of the Galaxy. We have also derived ^12^C/^13^C ratios from synthetic spectra of the first-overtone ^12^CO (2-0) and (3-1) and ^13^CO (2-0) lines near 23440{AA} and ^13^CO (3-1) lines at about 23730{AA}. Comparison of our results with the ones obtained from the optical region suggests that the IGRINS high-resolution H- and K-band spectra offer more internally self-consistent line abundances of the same species for several elements, especially the {alpha}-elements. This in turn provides more reliable abundances for the elements with analytical difficulties in the optical spectral range.
- ID:
- ivo://CDS.VizieR/J/MNRAS/372/1259
- Title:
- Abundances of extragalactic globular clusters
- Short Name:
- J/MNRAS/372/1259
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of ages, metallicities and [alpha/Fe] ratios for 16 globular clusters (GCs) in NGC 147, 185 and 205 and of the central regions of the diffuse galaxy light in NGC 185 and 205. Our results are based on spectra obtained with the SCORPIO multislit spectrograph at the 6-m telescope of the Russian Academy of Sciences. We include in our analysis high-quality Hubble Space Telescope/WFPC2 photometry of individual stars in the studied GCs to investigate the influence of their horizontal branch (HB) morphology on the spectroscopic analysis. All our sample GCs appear to be old (T>8Gyr) and metal-poor ([Z/H]<1.1), except for the GCs Hubble V in NGC 205 (T=1.2+/-0.6Gyr, [Z/H]=0.6+/-0.2), Hubble VI in NGC 205 (T=4+/-2Gyr, [Z/H]=0.8+/-0.2) and FJJVII in NGC 185 (T=7+/-3Gyr, [Z/H]=0.8+/-0.2). The majority of our GCs sample has solar [alpha/Fe] enhancement in contrast to the halo population of GCs in M31 and the Milky Way. The HB morphologies for our sample GCs follow the same behaviour with metallicity as younger halo Galactic GCs. We show that it is unlikely that they bias our spectroscopic age estimates based on Balmer absorption-line indices. Spectroscopic ages and metallicities of the central regions in NGC 205 and 185 coincide with those obtained from colour-magnitude diagrams. The central field stellar populations in these galaxies have approximately the same age as their most central GCs (Hubble V in NGC 205 and FJJIII in NGC 185), but are more metal-rich than the central GCs.
- ID:
- ivo://CDS.VizieR/J/AJ/132/137
- Title:
- Abundances of extremely metal-poor carbon stars
- Short Name:
- J/AJ/132/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out a detailed abundance analysis using high-dispersion spectra from HIRES at Keck for a sample of 16 carbon stars found among candidate extremely metal-poor (EMP) stars from the Hamburg/ESO Survey (HES). We find that the Fe metallicities for the cooler C stars (Teff~5100K) have been underestimated by a factor of 10 by the standard HES tools. The results presented here provided crucial supporting data used recently by Cohen et al. (2005ApJ...633L.109C) to derive the frequency of C stars among EMP stars.
- ID:
- ivo://CDS.VizieR/J/AJ/127/1579
- Title:
- Abundances of faint M13 stars
- Short Name:
- J/AJ/127/1579
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Building upon earlier observations that demonstrate substantial star-to-star differences in the carbon abundances of M13 subgiants, we present new Keck LRIS spectra reaching more that 1.5mag below the M13 main-sequence turnoff (to V~20). Our analysis reveals a distribution of C abundances similar to that found among the subgiants, implying little change in the compositions of the M13 stars at least through the main-sequence turnoff. We presume these differences to be the result of some process operating early in the cluster history. Additional spectra of previously studied bright M13 giants have been obtained with the 5m Hale Telescope.
- ID:
- ivo://CDS.VizieR/J/A+A/441/1149
- Title:
- Abundances of 20 F-G disk stars
- Short Name:
- J/A+A/441/1149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Mn, Co and Eu abundances for a sample of 20 disk F and G dwarfs and subgiants with metallicities between -0.8 and +0.3. We investigate the influence of hyperfine structure (HFS) on the derived abundances of Mn and Co by using HFS data from different sources in the literature, as well as calculated HFS from interaction factors A and B.
- ID:
- ivo://CDS.VizieR/J/A+A/552/A6
- Title:
- Abundances of F-G main-sequence stars
- Short Name:
- J/A+A/552/A6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detailed chemical abundances of volatile and refractory elements have been discussed in the context of terrestrial-planet formation during in past years. The HARPS-GTO high-precision planet-search program has provided an extensive database of stellar spectra, which we have inspected in order to select the best-quality spectra available for late type stars. We study the volatile-to-refractory abundance ratios to investigate their possible relation with the low-mass planetary formation.
- ID:
- ivo://CDS.VizieR/J/A+A/364/102
- Title:
- Abundances of field BHB star candidates
- Short Name:
- J/A+A/364/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New spectroscopic observations are presented for a sample of thirty-one blue horizontal branch (BHB) star candidates that are sufficiently nearby to have reliable proper motions. Comments are given on a further twenty-five stars that have previously been suggested as BHB star candidates but which were not included in our sample. Moderately high-resolution spectra ({lambda}/{Delta}{lambda}=~15000) of twenty five of our program stars were taken with the coude feed spectrograph at Kitt Peak. Twelve of the program stars were also observed with the CAT spectrograph at ESO. Six of these program stars were observed from both hemispheres. IUE low-resolution spectra are available for most of our candidates and were used, in addition to other methods, in the determination of their T_eff_ and reddening. Abundances were obtained from these spectra using models computed by Castelli with an updated version of the ATLAS9 code (Kurucz, 1993, CD-ROM No. 13). All thirty one candidates are halo stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/864/57
- Title:
- Abundances of field & GC RR Lyrae. I. NGC3201
- Short Name:
- J/ApJ/864/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed spectroscopic analysis of horizontal branch stars in the globular cluster NGC 3201. We collected optical (4580-5330{AA}), high-resolution (~34000), high signal-to-noise ratio (~200) spectra for 11 RR Lyrae stars and one red horizontal branch star with the multifiber spectrograph M2FS with the 6.5m Magellan telescope at the Las Campanas Observatory. From measured equivalent widths, we derived atmospheric parameters and abundance ratios for {alpha} (Mg, Ca and Ti), iron-peak (Sc, Cr, Ni and Zn), and s-process (Y) elements. We found that NGC 3201 is a homogeneous, monometallic ([Fe/H]=-1.47+/-0.04), {alpha}-enhanced ([{alpha}/Fe]=0.37+/-0.04) cluster. The relative abundances of the iron-peak and s-process elements were found to be consistent with solar values. In comparison with other large stellar samples, NGC 3201 RR Lyraes have similar chemical enrichment histories as do those of other old (t>=10Gyr) Halo components (globular clusters; red giants; blue and red horizontal branch stars; and RR Lyraes). We also provided a new average radial velocity estimate for NGC 3201 by using a template velocity curve to overcome the limit of single-epoch measurements of variable stars: Vrad=494+/-2km/s ({sigma}=8km/s).
- ID:
- ivo://CDS.VizieR/J/A+A/511/A56
- Title:
- Abundances of five open clusters
- Short Name:
- J/A+A/511/A56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present number of Galactic open clusters that have high resolution abundance determinations, not only of [Fe/H], but also of other key elements, is largely insufficient to enable a clear modeling of the Galactic disk chemical evolution. To increase the number of Galactic open clusters with high quality measurements, we obtained high resolution (R~30000), high quality (S/N~50-100 per pixel), echelle spectra with the fiber spectrograph FOCES, at Calar Alto, Spain, for three red clump stars in each of five Open Clusters. We used the classical equivalent width analysis method to obtain accurate abundances of sixteen elements: Al, Ba, Ca, Co, Cr, Fe, La, Mg, Na, Nd, Ni, Sc, Si, Ti, V, and Y. We also derived the oxygen abundance using spectral synthesis of the 6300{AA} forbidden line.
- ID:
- ivo://CDS.VizieR/J/AJ/139/2289
- Title:
- Abundances of five red giants in M5
- Short Name:
- J/AJ/139/2289
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present LTE chemical abundances for five red giants and one AGB star in the Galactic globular cluster (GC) M5 based on high-resolution spectroscopy using the Magellan Inamori Kyocera Echelle spectrograph on the Magellan 6.5m Clay telescope. Our results are based on a line-by-line differential abundance analysis relative to the well-studied red giant Arcturus.
- ID:
- ivo://CDS.VizieR/J/MNRAS/492/1164
- Title:
- Abundances of Gaia DR2 wide binaries
- Short Name:
- J/MNRAS/492/1164
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One of the high-level goals of Galactic archaeology is chemical tagging of stars across the Milky Way to piece together its assembly history. For this to work, stars born together must be uniquely chemically homogeneous. Wide binary systems are an important laboratory to test this underlying assumption. Here we present the detailed chemical abundance patterns of 50 stars across 25 wide binary systems comprised of main-sequence stars of similar spectral type identified in Gaia DR2 with the aim of quantifying their level of chemical homogeneity. Using high-resolution spectra obtained with McDonald Observatory, we derive stellar atmospheric parameters and precise detailed chemical abundances for light/odd-Z (Li, C, Na, Al, Sc, V, Cu), alpha (Mg, Si, Ca), Fe-peak (Ti, Cr, Mn, Fe, Co, Ni, Zn), and neutron capture (Sr, Y, Zr, Ba, La, Nd, Eu) elements. Results indicate that 80% (20 pairs) of the systems are homogeneous in [Fe/H] at levels below 0.02dex. These systems are also chemically homogeneous in all elemental abundances studied, with offsets and dispersions consistent with measurement uncertainties. We also find that wide binary systems are far more chemically homogeneous than random pairings of field stars of similar spectral type. These results indicate that wide binary systems tend to be chemically homogeneous but in some cases they can differ in their detailed elemental abundances at a level of [X/H]~0.10dex, overall implying chemical tagging in broad strokes can work.
- ID:
- ivo://CDS.VizieR/J/A+A/465/799
- Title:
- Abundances of Galactic Bulge red giants
- Short Name:
- J/A+A/465/799
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper investigates the peculiar behaviour of the light elements (even, e.e. alpha-elements, and odd atomic numbers) in red giants of the galactic bulge, both in terms of the chemical evolution of the bulge, and in terms of possible deep-mixing mechanisms in these evolved stars. Abundances of the four light elements O, Na, Mg, and Al are measured in 13 core He-burning giant stars (red clump stars) and 40 red giant branch stars in four 25' fields spanning the bulge from -3 to -12{deg} galactic latitude. Special care was taken in the abundance analysis, performing a differential analysis with respect to the metal-rich solar-neighbourhood giant mu Leo, which best resembles our bulge sample stars. This approach minimises systematic effects that can arise in the analysis of cool metal-rich stars due to continuum definition issues and blending by molecular lines (CN) and, cancels out possible model atmosphere deficiencies.
- ID:
- ivo://CDS.VizieR/J/AJ/131/431
- Title:
- Abundances of Galactic G dwarfs
- Short Name:
- J/AJ/131/431
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have studied 23 long-lived G dwarfs that belong to the thin disk and thick disk stellar populations. The stellar data and analyses are identical, reducing the chances for systematic errors in the comparisons of the chemical abundance patterns in the two populations. Abundances have been derived for 24 elements: O, Na, Mg, Al, Si, Ca, Ti, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, and Eu.
- ID:
- ivo://CDS.VizieR/J/A+A/513/A35
- Title:
- Abundances of Galactic red giants
- Short Name:
- J/A+A/513/A35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation and evolution of the Galactic bulge and its relationship with the other Galactic populations is still poorly understood. To establish the chemical differences and similarities between the bulge and other stellar populations, we performed an elemental abundance analysis of alpha- (O, Mg, Si, Ca, and Ti) and Z-odd (Na and Al) elements of red giant stars in the bulge as well as of local thin disk, thick disk and halo giants. We use high-resolution optical spectra of 25 bulge giants in Baade's window and 55 comparison giants (4 halo, 29 thin disk and 22 thick disk giants) in the solar neighborhood. All stars have similar stellar parameters but cover a broad range in metallicity (-1.5<[Fe/H]<+0.5). A standard 1D local thermodynamic equilibrium analysis using both Kurucz and MARCS models yielded the abundances of O, Na, Mg, Al, Si, Ca, Ti and Fe. Our homogeneous and differential analysis of the Galactic stellar populations ensured that systematic errors were minimized.
- ID:
- ivo://CDS.VizieR/J/A+A/480/79
- Title:
- Abundances of giants in five Galactic clusters
- Short Name:
- J/A+A/480/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To constrain the formation and chemical evolution of the Galactic disk, we surveyed open clusters of different ages, metal contents, and distances form the Galactic centre. We employed FLAMES on VLT-UT2 to collect UVES spectra of five to ten giant stars in each of the selected clusters, and used them to derive the iron abundance and the detailed chemical composition. Equivalent widths were measured and abundance analysis was performed using the MOOG code and Kurucz model atmospheres on all stars accepted as cluster member on the basis of their radial velocity. We derived the atmospheric parameters and the abundance of Fe for NGC 2324 and NGC 2477 (average [Fe/H]=-0.17 with rms 0.05dex, and +0.07 with rms 0.03dex, respectively), two clusters never analyzed using high resolution spectroscopy. We also derived the abundances of Mg, Al, Ca, Si, Ti, Cr, Ni, and Ba for these two clusters and for NGC 2660, NGC 3960, and Berkeley 32, whose atmospheric parameters and metallicities were measured in a previous paper. We determined the reddening values for the five clusters, based on the spectroscopically determined temperatures, literature photometry, and a colour-temperature relation. All clusters show solar-scaled abundances for alpha- and Fe-peak elements, while [Na/Fe] appears slightly enhances and and [Ba/Fe] significantly enhanced. Our findings were compared to thin-disk stars and other open clusters, and no significant deviation from the standard behavior was found.
- ID:
- ivo://CDS.VizieR/J/A+A/488/943
- Title:
- Abundances of giants in four Galactic clusters
- Short Name:
- J/A+A/488/943
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To constrain the formation and chemical evolution of the Galactic disk, we surveyed open clusters of different ages, metal contents, and distances form the Galactic centre. We employed FLAMES on VLT-UT2 to collect UVES spectra of bright giant stars in each of the selected clusters, and used them to derive the iron abundance and the detailed chemical composition. Equivalent widths were measured and abundance analysis was performed using the MOOG code and Kurucz model atmospheres. We derived the abundance of Fe for Mg, Al, Ca, Si, Ti, Cr, Ni, and Ba. We employed direct line profile fitting to derive non-LTE Na abundances. We found [Fe/H]=-0.30, -0.31, +0.13, -0.33 for Be 20, Be 29, Cr 261, and Melotte 66, respectively (with rms values of 0.02 to 0.05dex). Alpha- and Fe-peak elements have solar ratios, Ba is enhanced, and Na has solar ratios, suggesting that treatment of non-LTE is very important. We confirm the presence of a metallicity gradient in the inner disk, and a flattening in the outer part.
- ID:
- ivo://CDS.VizieR/J/A+A/554/A81
- Title:
- Abundances of 16 giants in M75
- Short Name:
- J/A+A/554/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- M75 is a relatively young Globular Cluster (GC) found at 15kpc from the Galactic centre at the transition region between the inner and outer Milky Way halos. Our aims are to perform a comprehensive abundance study of a variety of chemical elements in this GC such as to investigate its chemical enrichment history in terms of early star formation, and to search for any multiple populations. We have obtained high resolution spectroscopy with the MIKE instrument at the Magellan telescope for 16 red giant stars. Their membership within the GC is confirmed from radial velocity measurements. Our chemical abundance analysis is performed via equivalent width measurements and spectral synthesis, assuming local thermodynamic equilibrium (LTE). We present the first comprehensive abundance study of M75 to date. The cluster is metal-rich ([Fe/H]=-1.16+/-0.02dex, [alpha/Fe]=+0.30+/-0.02dex), and shows a marginal spread in [Fe/H] of 0.07dex, typical of most GCs of similar luminosity. A moderately extended O-Na anticorrelation is clearly visible, likely showing three generations of stars, formed on a short timescale. Additionally the two most Na-rich stars are also Ba-enhanced by 0.4 and 0.6dex, respectively, indicative of pollution by lower mass (M~4-5M_{sun}_) Asymptotic Giant Branch (AGB) stars. The overall n-capture element pattern is compatible with predominant r-process enrichment, which is rarely the case in GCs of such a high metallicity.
- ID:
- ivo://CDS.VizieR/J/ApJ/732/108
- Title:
- Abundances of 92 giants in Plaut's window
- Short Name:
- J/ApJ/732/108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Fe, Si, and Ca abundances for 61 giants in Plaut's window (l=-1{deg}, b=-8.5{deg}) and Fe abundances for an additional 31 giants in a second, nearby field (l=0{deg}, b=-8{deg}) derived from high-resolution (R~25000) spectra obtained with the Blanco 4m telescope and Hydra multifiber spectrograph. The median metallicity of red giant branch (RGB) stars in the Plaut's field is ~0.4dex lower than those in Baade's window, and confirms the presence of an iron abundance gradient along the bulge minor axis. The full metallicity range of our (biased) RGB sample spans -1.5<[Fe/H]<+0.3, which is similar to that found in other bulge fields. We also derive a photometric metallicity distribution function for RGB stars in the (l=-1{deg}, b=-8.5{deg}) field and find very good agreement with the spectroscopic metallicity distribution. The radial velocity (RV) and dispersion data for the bulge RGB stars are in agreement with previous results of the Bulge Radial Velocity Assay survey, and we find evidence for a decreasing velocity dispersion with increasing [Fe/H]. The [{alpha}/Fe] enhancement in Plaut field stars is nearly identical to that observed in Baade's window, and suggests that an [{alpha}/Fe] gradient does not exist between b=-4{deg} and -8{deg}. Additionally, a subset of our sample (23 stars) appears to be foreground red clump stars that are very metal rich, exhibit small metallicity and RV dispersions, and are enhanced in {alpha} elements. While these stars likely belong to the Galactic inner disk population, they exhibit [{alpha}/Fe] ratios that are enhanced above the thin and thick disk.
- ID:
- ivo://CDS.VizieR/J/MNRAS/433/1892
- Title:
- Abundances of 848 giants of {omega} Cen
- Short Name:
- J/MNRAS/433/1892
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the effective temperatures, surface gravities and abundances of iron, carbon and barium of 848 giant branch stars, of which 557 also have well-defined nitrogen abundances, of the globular cluster {omega} Centauri. This work used photometric sources and lower resolution spectra for this abundance analysis. Spectral indices were used to estimate the oxygen abundance of the stars, leading to a determination of whether a particular star was oxygen rich or oxygen poor. The 557-star subset was analysed in the context of evolutionary groups, with four broad groups identified. These groups suggest that there were at least four main periods of star formation in the cluster. The exact order of these star formation events is not yet understood. These results compare well with those found at higher resolution and show the value of more extensive lower resolution spectral surveys. They also highlight the need for large samples of stars when working with a complex object like {omega} Cen.
- ID:
- ivo://CDS.VizieR/J/A+A/347/69
- Title:
- Abundances of halo early-type stars
- Short Name:
- J/A+A/347/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present echelle (R~40,000) spectroscopic observations for a sample of apparently normal, high Galactic latitude, early-type stars drawn from the Palomar-Green Survey. The metal-line spectra show evidence for rotational velocity broadening with values of vsini<=300km/s. In conjunction with Kurucz model atmospheres, we derive stellar photospheric abundances that are consistent with a Population I chemical composition; differential abundances with respect to Galactic disk Population I stars indicate no abundance differences outside the estimated errors. From a comparison of the derived atmospheric parameters with recent theoretical evolutionary models, we derive distance and age estimates for individual stars. Using kinematical considerations, we conclude that all these objects are `runaway' stars, formed in the Galactic disk and subsequently ejected, possibly by supernovae explosions or dynamical interactions.
- ID:
- ivo://CDS.VizieR/J/A+A/493/913
- Title:
- Abundances of 9 HB stars in NGC 6352
- Short Name:
- J/A+A/493/913
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Metal-rich globular clusters provide important tracers of the formation of our Galaxy. Moreover, and not less important, they are very important calibrators for the derivation of properties of extra-galactic metal-rich stellar populations. Nonetheless, only a few of the metal-rich globular clusters in the Milky Way have been studied using high-resolution stellar spectra to derive elemental abundances. Additionally, Rosenberg et al. identified a small group of metal-rich globular clusters that appeared to be about 2 billion years younger than the bulk of the Milky Way globular clusters. However, it is unclear if like is compared with like in this dataset as we do not know the enhancement of alpha-elements in the clusters and the amount of alpha-elements is well known to influence the derivation of ages for globular clusters. We present a study of elemental abundances for alpha and iron-peak elements for nine HB stars in the metal-rich globular cluster NGC 6352. The elemental abundances are based on high-resolution, high signal-to-noise spectra obtained with the UVES spectrograph on VLT. The elemental abundances have been derived using standard LTE calculations and stellar parameters have been derived from the spectra themselves by requiring ionizational as well as excitational equilibrium. We find that NGC 6352 has [Fe/H]=-0.55, is enhanced in the alpha-elements to about +0.2dex for Ca, Si, and Ti relative to Fe. For the iron-peak elements we find solar values. Based on the spectroscopically derived stellar parameters we find that an E(B-V)=0.24 and (m-M).
- ID:
- ivo://CDS.VizieR/J/A+A/430/255
- Title:
- Abundances of HD221170
- Short Name:
- J/A+A/430/255
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the abundance determination in the atmosphere of the bright halo star HD 221170. The spectra were taken with the Terskol Observatory's 2.0-m telescope with a resolution R=45000 and signal-to-noise ratio up to 250 in the wavelength region 3638-10275{AA}. The abundances of 43 chemical elements were determined with the method of spectrum synthesis.
- ID:
- ivo://CDS.VizieR/J/ApJ/645/613
- Title:
- Abundances of HD 221170
- Short Name:
- J/ApJ/645/613
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Employing high-resolution spectra obtained with the near-UV-sensitive detector on the Keck I HIRES, supplemented by data obtained with the McDonald Observatory 2d-coude, we have performed a comprehensive chemical composition analysis of the bright r-process-rich metal-poor red giant star HD 221170. Analysis of 57 individual neutral and ionized species yielded abundances for a total of 46 elements and significant upper limits for an additional five. Model stellar atmosphere parameters were derived with the aid of ~200 Fe peak transitions. From more than 350 transitions of 35 neutron-capture (Z>30) species, abundances for 30 neutron-capture elements and upper limits for three others were derived. Utilizing 36 transitions of La, 16 of Eu, and seven of Th, we derive ratios of log{epsilon}(Th/La)=-0.73 ({sigma}=0.06) and log{epsilon}(Th/Eu)=-0.60 ({sigma}=0.05), values in excellent agreement with those previously derived for other r-process-rich metal-poor stars such as CS 22892-052, BD +17 3248, and HD 115444. Based on the Th/Eu chronometer, the inferred age is 11.7+/-2.8Gyr. The abundance distribution of the heavier neutron-capture elements (Z>=56) is fitted well by the predicted scaled solar system r-process abundances, as also seen in other r-process-rich stars. Unlike other r-process-rich stars, however, we find that the abundances of the lighter neutron-capture elements (37<Z<56) in HD 221170 are also in agreement with the abundances predicted for the scaled solar r-process pattern.
- ID:
- ivo://CDS.VizieR/J/MNRAS/370/2091
- Title:
- Abundances of HD 134439/40 and HD 211998
- Short Name:
- J/MNRAS/370/2091
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Abundances of 18 elements are determined for the common proper-motion pair, HD 134439 and HD 134440, which shows high [Mn/Fe] and low [alpha/Fe] ratios as compared to normal halo stars. Moreover, puzzling abundances are indicated from elements whose origins are normally considered to be from the same nucleosynthesis history. Particularly, we have found that [Mg/Fe] and [Si/Fe] are lower than [Ca/Fe] and [Ti/Fe] by 0.1-0.3dex. When elemental abundances are interpreted in term of their condensation temperatures (T_C_), obvious trends of [X/Fe] versus TC for alpha elements and probably iron-peak elements as well are shown. The hypothesis that these stars have formed from a dusty environment in dwarf spheroidal (dSph) galaxy provides a solution to the puzzling abundance pattern.
- ID:
- ivo://CDS.VizieR/J/A+A/368/250
- Title:
- Abundances of HDE 341617
- Short Name:
- J/A+A/368/250
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detailed atmospheric abundances have been calculated for a sample of A-G supergiant stars with IR fluxes and/or high galactic latitudes. HD 172481 and HD 158616 show clear indications of being post-AGB stars that have experienced third dredge-up. HD 158616 is carbon-rich while the abundance pattern of HD 172481 and its large Li enhancement gives support to the hot bottom burning scenario that explains paucity of carbon-rich stars among AGB stars. HD 172324 is very likely a hot post-AGB star that shows a strong carbon deficiency. HD 725, HD 218753 and HD 331319 also appear to be evolved objects between the red giant and the AGB. HD 9167, HD 173638 with a few exceptions, reflect solar abundances and no signs of post red giant evolution. They are most likely young massive disk supergiants. Further analysis of proto-Planetary Nebula HDE 341617 reveals that He lines show signs of velocity stratification. The emission lines have weakened considerably since 1993. The envelope expands at 19km/s relative to the star. Atmospheric abundances, evolutionary tracks and isochrones are used to estimate masses and ages of all stars in the sample.
- ID:
- ivo://CDS.VizieR/J/ApJ/900/123
- Title:
- Abundances of heavy ions in ICMEs from 1998-2011
- Short Name:
- J/ApJ/900/123
- Date:
- 20 Jan 2022 00:43:36
- Publisher:
- CDS
- Description:
- This statistical work studies the abundances and the charge states of the carbon, oxygen, and iron ions in 281 interplanetary coronal mass ejections (ICMEs) measured at 1 au by ACE spacecraft from 1998 to 2011. The Gaussian distribution test is applied, and the analysis of variance is used to quantify the similarity between two distributions of ionic charge states and abundances. The correlation coefficient is calculated to reveal the dependence of the abundances and the mean charge of heavy ions on the solar activity. The results show that the mean charge, the abundance, and the speed at 1 au are highly related to the sunspot number (SN). The O7+/O6+ shows statistical difference between the high speed and the low speed groups of ICMEs. Different from the cold materials inside ICMEs, the mean charge of carbon ions shows a positive relation to that of oxygen ions. The Mg/O in the studied ICMEs are much higher than that in the solar wind. Three types of charge distribution of C, O, and Fe ions are summarized. The fraction of each of the three types is related to the solar minimum or the solar maximum. The mean charge and the flux of oxygen ions show quasi-linear relations to the SN during solar minimum, and show fluctuations during maximum. The results reveal that the solar activity, which represents the solar magnetic field status by nature, controls the composition of heavy ions in ICMEs.
- ID:
- ivo://CDS.VizieR/J/AZh/79/867
- Title:
- Abundances of HII regions in blue galaxies
- Short Name:
- J/AZh/79/867
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New expression for the ionization correction factors (ICF) are used to find the nebular-gas compositions in HII regions in blue compact dwarf galaxies (BCD). The abundances of He, N, O, Ne, S, and Ar in 41 HII regions are determined.
- ID:
- ivo://CDS.VizieR/J/A+AS/129/563
- Title:
- Abundances of HR 4487, 14 Hyd and 3 Cen A
- Short Name:
- J/A+AS/129/563
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ussing CASLEO echelle spectrograms, elemental abundances are derived for the sharp-lined non-magnetic CP stars HR 4487, 14 Hya and 3 Cen A. The first two stars are members of the Mercury-Manganese subgroup and have abundances which are similar to other such peculiar stars. The third is a hotter related star. The detection of Mn II lines in its spectrum adds to this relationship.
- ID:
- ivo://CDS.VizieR/J/MNRAS/422/2969
- Title:
- Abundances of 19 K-type giants in moving groups
- Short Name:
- J/MNRAS/422/2969
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the stellar parameters of 19 K-type giants and their abundances for 13 chemical elements (Al, Ba, Ca, Fe, K, Mg, Mn, Na, Ni, Sc, Si, Ti and V), selected from two moving groups, covering the metallicity range of -0.6<[Fe/H]<0.2, based on high-resolution spectra. Most of the elemental abundances show similar trends as in previous studies, except for Al, Na and Ba, which are seriously affected by evolution. The abundance ratios of [Na/Mg] increase smoothly with higher [Mg/H], and those of [Al/Mg] decrease slightly with increasing [Mg/H]. The abundance ratios of [Mg/Ba] show a distinction between these two moving groups, which is mainly induced by chemical evolution and also partly by kinematic effects. The inhomogeneous metallicity of each star from the moving groups demonstrates that these stars had different chemical origins before they were kinematically aggregated. This favours a dynamical resonant theory.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/5
- Title:
- Abundances of LAMOST giants from APOGEE DR12
- Short Name:
- J/ApJ/836/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this era of large-scale spectroscopic stellar surveys, measurements of stellar attributes ("labels," i.e., parameters and abundances) must be made precise and consistent across surveys. Here, we demonstrate that this can be achieved by a data-driven approach to spectral modeling. With The Cannon, we transfer information from the APOGEE survey to determine precise T_eff_, logg, [Fe/H], and [{alpha}/M] from the spectra of 450000 LAMOST giants. The Cannon fits a predictive model for LAMOST spectra using 9952 stars observed in common between the two surveys, taking five labels from APOGEE DR12 as ground truth T_eff_, logg, [Fe/H], [{alpha}/M], and K-band extinction A_k_. The model is then used to infer T_eff_, logg, [Fe/H], and [{alpha}/M] for 454180 giants, 20% of the LAMOST DR2 stellar sample. These are the first [{alpha}/M] values for the full set of LAMOST giants, and the largest catalog of [{alpha}/M] for giant stars to date. Furthermore, these labels are by construction on the APOGEE label scale; for spectra with S/N>50, cross-validation of the model yields typical uncertainties of 70K in T_eff_, 0.1 in logg, 0.1 in [Fe/H], and 0.04 in [{alpha}/M], values comparable to the broadly stated, conservative APOGEE DR12 uncertainties. Thus, by using "label transfer" to tie low-resolution (LAMOST R~1800) spectra to the label scale of a much higher-resolution (APOGEE R~22500) survey, we substantially reduce the inconsistencies between labels measured by the individual survey pipelines. This demonstrates that label transfer with The Cannon can successfully bring different surveys onto the same physical scale.
- ID:
- ivo://CDS.VizieR/III/27A
- Title:
- Abundances of late G/K dwarfs in solar neighborhood
- Short Name:
- III/27A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this investigation, a technique developed by Spinrad and Taylor for obtaining metal abundances of late-type stars, and used by them in an earlier investigation of evolved stars (see Cat. II/47), is applied to field dwarfs in the solar vicinity and to the Hyades. The colors determined from photoelectric spectrum-scanner observations are listed in the "raw_data.dat" file; the derived blocking factors are given in the "blocking.dat" file. These results were published as the Table 5 of the paper.
- ID:
- ivo://CDS.VizieR/J/AJ/145/52
- Title:
- Abundances of late K and M dwarfs in binary systems
- Short Name:
- J/AJ/145/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Knowledge of late K and M dwarf metallicities can be used to guide planet searches and constrain planet formation models. However, the determination of metallicities of late-type stars is difficult because visible wavelength spectra of their cool atmospheres contain many overlapping absorption lines, preventing the measurement of equivalent widths. We present new methods, and improved calibrations of existing methods, to determine metallicities of late K and M dwarfs from moderate resolution (1300<R<2000) visible and infrared spectra. We select a sample of 112 wide binary systems that contain a late-type companion to a solar-type primary star. Our sample includes 62 primary stars with previously published metallicities, as well as 50 stars with metallicities determined from our own observations. We use our sample to empirically determine which features in the spectrum of the companion are best correlated with the metallicity of the primary. We find ~120 features in K and M dwarf spectra that are useful for predicting metallicity. We derive metallicity calibrations for different wavelength ranges, and show that it is possible to get metallicities reliable to <0.10dex using either visible, J-, H-, or K-band spectra. We find that the most accurate metallicities derived from visible spectra requires the use of different calibrations for early-type (K5.5-M2) and late-type (M2-M6) dwarfs. Our calibrations are applicable to dwarfs with metallicities of -1.04<[Fe/H]<+0.56 and spectral types from K7 to M5. Lastly, we use our sample of wide binaries to test and refine existing calibrations to determine M dwarf metallicities. We find that the {zeta} parameter, which measures the ratio of TiO can CaH bands, is correlated with [Fe/H] for super-solar metallicities, and {zeta} does not always correctly identify metal-poor M dwarfs. We also find that existing calibrations in the K and H bands are quite reliable for stars with [Fe/H]>-0.5, but are less useful for more metal-poor stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/797/69
- Title:
- Abundances of late-type stars
- Short Name:
- J/ApJ/797/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of several absorption lines of neutral phosphorus (P, Z=15) in archival near-ultraviolet spectra obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. We derive phosphorus abundances or interesting upper limits in 14 late-type stars with metallicities spanning -3.8<[Fe/H]<-0.1. Previously, phosphorus had only been studied in Galactic stars with -1.0<[Fe/H]<+0.3. Iron lines reveal abundance offsets between the optical and ultraviolet regions, and we discuss and apply a correction factor to account for this offset. In stars with [Fe/H]>-1.0, the [P/Fe] ratio decreases toward the solar value with increasing metallicity, in agreement with previous observational studies. In stars with [Fe/H]<-1.0, $<[P/Fe]$>=+0.04+/-0.10, which overlaps with the [P/Fe] ratios found in several high-redshift damped Lyman-{alpha} systems. This behavior hints at a primary origin in massive stars.
- ID:
- ivo://CDS.VizieR/J/A+A/560/A44
- Title:
- Abundances of LMC bar and disk stars
- Short Name:
- J/A+A/560/A44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper compares the chemical evolution of the Large Magellanic Cloud (LMC) to that of the Milky Way (MW) and investigates the relation between the bar and the inner disc of the LMC in the context of the formation of the bar. We obtained high-resolution and mid signal-to-noise ratio spectra with FLAMES/GIRAFFE at ESO/VLT (Proposals 072.B-0293(B) and 078.B-0323(A), P.I. Vanessa Hill) and performed a detailed chemical analysis of 106 and 58 LMC field red giant stars (mostly older than 1Gyr), located in the bar and the disc of the LMC respectively. To validate our stellar parameter determinations and abundance measurement procedures, we performed thorough tests using the well-known mildly metal-poor Milky-Way thick disc giant Arcturus (HD 124897, alpha Boo). We measured elemental abundances for O, Mg, Si, Ca, Ti (alpha-elements), Na (light odd element), Sc, V, Cr, Co, Ni, Cu (iron-peak elements), Y, Zr, Ba, La and Eu (s- and r-elements). We used the automated tool DAOSPEC to measure the equivalent width (EW) and their associated error, and we used the grid of OSMARCS model atmospheres together with the spectrum synthesis code turbospectrum to convert the EW into abundances. Since our stars are giants, atmosphere models and radiative transfer were both in spherical geometry. We built the atmosphere model for a given set of stellar parameters by interpolation onto the OSMARCS grid with the interpolation routine written by T. Masseron.
262. Abundances of LX Per
- ID:
- ivo://CDS.VizieR/J/AJ/145/167
- Title:
- Abundances of LX Per
- Short Name:
- J/AJ/145/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopic observations of LX Per carried out using the Korean Bohyunsan Observatory Echelle Spectrograph (BOES) with spectral resolving power R=80000. The spectrograph was attached to the 1.8m telescope. The fit of synthetic spectra to the observed spectrum of the system allowed us to find the component parameters and the abundances of chemical elements in the atmospheres of the components. The strong CaII H&K emissions are confirmed; we also found emission lines in the CaII reversals' triplet absorptions at the wavelengths of 8498, 8542, and 8662{AA} in the spectrum of the cooler component of LX Per. A unique photometric solution using the distorted light curves of three different epochs was made. The spot model light curves were fitted to the 1981, 1982, and 1983 observations successfully by adjusting only spot parameters. We could infer that the variation of spot location and size was the main reason for the changing shape of light curves. The main feature of the abundance patterns of both components was the apparent deficiency of heavy (Z>30) elements. Only elements with strong lines, namely Y and Ba, were detected. Correlations of relative abundances of chemical elements with condensation temperatures and second ionization potentials of these elements, which can be explained by the accretion of dust and gas, were found.
- ID:
- ivo://CDS.VizieR/J/ApJ/882/177
- Title:
- Abundances of 4 member stars of Tucana III
- Short Name:
- J/ApJ/882/177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a chemical abundance analysis of four additional confirmed member stars of Tucana III, a Milky Way satellite galaxy candidate in the process of being tidally disrupted as it is accreted by the Galaxy. Two of these stars are centrally located in the core of the galaxy while the other two stars are located in the eastern and western tidal tails. The four stars have chemical abundance patterns consistent with the one previously studied star in Tucana III: they are moderately enhanced in r-process elements, i.e., they have <[Eu/Fe]>~+0.4dex. The non-neutron-capture elements generally follow trends seen in other dwarf galaxies, including a metallicity range of 0.44 dex and the expected trend in {alpha}-elements, i.e., the lower metallicity stars have higher Ca and Ti abundances. Overall, the chemical abundance patterns of these stars suggest that Tucana III was an ultra-faint dwarf galaxy, and not a globular cluster, before being tidally disturbed. As is the case for the one other galaxy dominated by r-process enhanced stars, Reticulum II, Tucana III's stellar chemical abundances are consistent with pollution from ejecta produced by a binary neutron star merger, although a different r-process element or dilution gas mass is required to explain the abundances in these two galaxies if a neutron star merger is the sole source of r-process enhancement.
- ID:
- ivo://CDS.VizieR/J/ApJ/817/41
- Title:
- Abundances of 4 metal-poor red giants in BooII
- Short Name:
- J/ApJ/817/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution Magellan/MIKE spectra of the four brightest confirmed red giant stars in the ultra-faint dwarf galaxy Bootes II (Boo II). These stars all inhabit the metal-poor tail of the BooII metallicity distribution function. The chemical abundance pattern of all detectable elements in these stars is consistent with that of the Galactic halo. However, all four stars have undetectable amounts of neutron-capture elements Sr and Ba, with upper limits comparable to the lowest ever detected in the halo or in other dwarf galaxies. One star exhibits significant radial velocity variations over time, suggesting it to be in a binary system. Its variable velocity has likely increased past determinations of the Boo II velocity dispersion. Our four stars span a limited metallicity range, but their enhanced {alpha}-abundances and low neutron-capture abundances are consistent with the interpretation that Boo II has been enriched by very few generations of stars. The chemical abundance pattern in Boo II confirms the emerging trend that the faintest dwarf galaxies have neutron-capture abundances distinct from the halo, suggesting the dominant source of neutron-capture elements in halo stars may be different than in ultra-faint dwarfs.
- ID:
- ivo://CDS.VizieR/J/ApJ/821/37
- Title:
- Abundances of metal-poor star HD 94028
- Short Name:
- J/ApJ/821/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed analysis of the composition and nucleosynthetic origins of the heavy elements in the metal-poor ([Fe/H]=-1.62+/-0.09) star HD 94028. Previous studies revealed that this star is mildly enhanced in elements produced by the slow neutron-capture process (s process; e.g., [Pb/Fe]=+0.79+/-0.32) and rapid neutron-capture process (r process; e.g., [Eu/Fe]=+0.22+/-0.12), including unusually large molybdenum ([Mo/Fe]= +0.97+/-0.16) and ruthenium ([Ru/Fe]=+0.69+/-0.17) enhancements. However, this star is not enhanced in carbon ([C/Fe]=-0.06+/-0.19). We analyze an archival near-ultraviolet spectrum of HD 94028, collected using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, and other archival optical spectra collected from ground-based telescopes. We report abundances or upper limits derived from 64 species of 56 elements. We compare these observations with s-process yields from low-metallicity AGB evolution and nucleosynthesis models. No combination of s- and r-process patterns can adequately reproduce the observed abundances, including the super-solar [As/Ge] ratio (+0.99+/-0.23) and the enhanced [Mo/Fe] and [Ru/Fe] ratios. We can fit these features when including an additional contribution from the intermediate neutron-capture process (i process), which perhaps operated through the ingestion of H in He-burning convective regions in massive stars, super-AGB stars, or low-mass AGB stars. Currently, only the i process appears capable of consistently producing the super-solar [As/Ge] ratios and ratios among neighboring heavy elements found in HD 94028. Other metal-poor stars also show enhanced [As/Ge] ratios, hinting that operation of the i process may have been common in the early Galaxy.
- ID:
- ivo://CDS.VizieR/J/A+A/654/A170
- Title:
- Abundances of metal-poor stars
- Short Name:
- J/A+A/654/A170
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The study of old, metal-poor stars deepens our knowledge on the early stages of the universe. In particular, the study of these stars gives us a valuable insight into the masses of the first massive stars and their emission of ionising photons. We present a detailed chemical analysis and determination of the kinematic and orbital properties of a sample of 11 dwarf stars. These are metal-poor stars, and a few of them present a low lithium content. We inspected whether the other elements also present anomalies. We analysed the high-resolution UVES spectra of a few metal-poor stars using the Turbospectrum code to synthesise spectral lines profiles. This allowed us to derive a detailed chemical analysis of Fe, C, Li, Na, Mg, Al, Si, CaI, CaII, ScII, TiII, Cr, Mn, Co, Ni, Sr, and Ba. We find excellent coherence with the reference metal-poor First Stars sample. The lithium-poor stars do not present any anomaly of the abundance of the elements other than lithium. Among the Li-poor stars, we show that CS 22882-027 is very probably a blue-straggler. The star CS 30302-145, which has a Li abundance compatible with the plateau, has a very low Si abundance and a high Mn abundance. In many aspects, it is similar to the {alpha}-poor star HE 1424-0241, but it is less extreme. It could have been formed in a satellite galaxy and later been accreted by our Galaxy. This hypothesis is also supported by its kinematics.
- ID:
- ivo://CDS.VizieR/J/AN/331/474
- Title:
- Abundances of metal-poor stars
- Short Name:
- J/AN/331/474
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The abundance patterns of the most metal-poor stars in the Galactic halo and small dwarf galaxies provide us with a wealth of information about the early Universe. In particular, these old survivors allow us to study the nature of the first stars and supernovae, the relevant nucleosynthesis processes responsible for the formation and evolution of the elements, early star- and galaxy formation processes, as well as the assembly process of the stellar halo from dwarf galaxies a long time ago. This review presents the current state of the field of "stellar archaeology" -- the diverse use of metal-poor stars to explore the high-redshift Universe and its constituents. In particular, the conditions for early star formation are discussed, how these ultimately led to a chemical evolution, and what the role of the most iron-poor stars is for learning about Population III supernovae yields. Rapid neutron-capture signatures found in metal-poor stars can be used to obtain stellar ages, but also to constrain this complex nucleosynthesis process with observational measurements. Moreover, chemical abundances of extremely metal-poor stars in different types of dwarf galaxies can be used to infer details on the formation scenario of the halo and the role of dwarf galaxies as Galactic building blocks. I conclude with an outlook as to where this field may be heading within the next decade. A table of ~1000 metal-poor stars and their abundances as collected from the literature is provided in electronic format.
- ID:
- ivo://CDS.VizieR/J/A+A/645/A61
- Title:
- Abundances of 25 metal-poor stars
- Short Name:
- J/A+A/645/A61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Among carbon-enhanced metal-poor (CEMP) stars, some are found to be enriched in slow-neutron capture (s-process) elements (and are then tagged CEMP-s), some have overabundances in rapid-neutron capture (r-process) elements (tagged CEMP-r), and some are characterized by both s- and r-process enrichments (tagged CEMP-rs). The current distinction between CEMP-s and CEMP-rs is based on their [Ba/Fe] and [Eu/Fe] ratios, since barium and europium are predominantly produced by the s- and the r-process, respectively. The origin of the abundance differences between CEMP-s and CEMP-rs stars is presently unknown. It has been claimed that the i-process, whose site still remains to be identified, could better reproduce CEMP-rs abundances than the s-process. We propose a more robust classification method for CEMP-s and CEMP-rs stars using additional heavy elements other than Ba and Eu. Once a secure classification is available, it should then be possible to assess whether the i-process or a variant of the s-process better fits the peculiar abundance patterns of CEMP-rs stars. We analyse high-resolution spectra of 24 CEMP stars and one r-process enriched star without carbon-enrichment, observed mainly with the high-resolution HERMES spectrograph mounted on the Mercator telescope (La Palma) and also with the UVES spectrograph on VLT (ESO Chile) and HIRES spectrograph on KECK (Hawaii). Stellar parameters and abundances are derived using MARCS model atmospheres. Elemental abundances are computed through spectral synthesis using the TURBOSPECTRUM radiative transfer code. Stars are re-classified as CEMP-s or -rs according to a new classification scheme using eight heavy element abundances. Within our sample of 25 objects, the literature classification is globally confirmed, except for HE 1429-0551 and HE 2144-1832, previously classified as CEMP-rs and now as CEMP-s stars. The abundance profiles of CEMP-s and CEMP-rs stars are compared in detail, and no clear separation is found between the two groups; it seems instead that there is an abundance continuum between the two stellar classes. There is an even larger binarity rate among CEMP-rs stars than among CEMP-s stars, indicating that CEMP-rs stars are extrinsic stars as well. The second peak s-process elements (Ba, La, Ce) are slightly enhanced in CEMP-rs stars with respect to first-peak s-process elements (Sr, Y, Zr), when compared to CEMP-s stars. Models of radiative s-process nucleosynthesis during the interpulse phases reproduce well the abundance profiles of CEMP-s stars, whereas those of CEMP-rs stars are explained well by low-metallicity 1M_{sun}_ models experiencing proton ingestion. The global fitting of our i-process models to CEMP-rs stars is as good as the one of our s-process models to CEMP-s stars. Stellar evolutionary tracks of an enhanced carbon composition (consistent with our abundance determinations) are necessary to explain the position of CEMP-s and CEMP-rs stars in the Hertzsprung-Russell (HR) diagram using Gaia DR2 parallaxes; they are found to lie mostly on the red giant branch (RGB). CEMP-rs stars present most of the characteristics of extrinsic stars such as CEMP-s, CH, barium, and extrinsic S stars; they can be explained as being polluted by a low-mass, low-metallicity thermally-pulsing asymptotic giant branch (TP-AGB) companion experiencing i-process nucleosynthesis after proton ingestion during its first convective thermal pulses. As such, they could be renamed CEMP-sr stars, since they represent a particular manifestation of the s-process at low-metallicities. For these objects a call for an exotic i-process site may not necessarily be required anymore.
- ID:
- ivo://CDS.VizieR/J/ApJ/852/99
- Title:
- Abundances of 3 metal-poor stars in Horologium I
- Short Name:
- J/ApJ/852/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present chemical abundance measurements of three stars in the ultrafaint dwarf galaxy Horologium I, a Milky Way satellite discovered by the Dark Energy Survey. Using high-resolution spectroscopic observations, we measure the metallicity of the three stars, as well as abundance ratios of several {alpha}-elements, iron-peak elements, and neutron-capture elements. The abundance pattern is relatively consistent among all three stars, which have a low average metallicity of [Fe/H]~-2.6 and are not {alpha}-enhanced ([{alpha}/Fe]~0.0). This result is unexpected when compared to other low-metallicity stars in the Galactic halo and other ultrafaint dwarfs and suggests the possibility of a different mechanism for the enrichment of Hor I compared to other satellites. We discuss possible scenarios that could lead to this observed nucleosynthetic signature, including extended star formation, enrichment by a Population III supernova, and or an association with the Large Magellanic Cloud.
- ID:
- ivo://CDS.VizieR/J/ApJ/856/142
- Title:
- Abundances of metal-poor stars in Sculptor
- Short Name:
- J/ApJ/856/142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study of the chemical abundances of metal-poor stars in dwarf galaxies provides a venue to constrain paradigms of chemical enrichment and galaxy formation. Here we present metallicity and carbon abundance measurements of 100 stars in Sculptor from medium-resolution (R~2000) spectra taken with the Magellan/Michigan Fiber System mounted on the Magellan-Clay 6.5m telescope at Las Campanas Observatory. We identify 24 extremely metal-poor star candidates ([Fe/H]{<}-3.0) and 21 carbon-enhanced metal-poor (CEMP) star candidates. Eight carbon-enhanced stars are classified with at least 2{sigma} confidence, and five are confirmed as such with follow-up R~6000 observations using the Magellan Echellette Spectrograph on the Magellan-Baade 6.5m telescope. We measure a CEMP fraction of 36% for stars below [Fe/H]=-3.0, indicating that the prevalence of carbon-enhanced stars in Sculptor is similar to that of the halo (~43%) after excluding likely CEMP-s and CEMP-r/s stars from our sample. However, we do not detect that any CEMP stars are strongly enhanced in carbon ([C/Fe]>1.0). The existence of a large number of CEMP stars both in the halo and in Sculptor suggests that some halo CEMP stars may have originated from accreted early analogs of dwarf galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/160/173
- Title:
- Abundances of metal-poor stars in the Inner Bulge
- Short Name:
- J/AJ/160/173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The bulge is the oldest component of the Milky Way. Since numerous simulations of Milky Way formation have predicted that the oldest stars at a given metallicity are found on tightly bound orbits, the Galaxy's oldest stars are likely metal-poor stars in the inner bulge with small apocenters (i.e., Rapo <~4kpc). In the past, stars with these properties have been impossible to find due to extreme reddening and extinction along the line of sight to the inner bulge. We have used the mid-infrared metal-poor star selection of Schlaufman & Casey (2014) on Spitzer/Galactic Legacy Infrared Mid-Plane Survey Extraordinaire data to overcome these problems and target candidate inner bulge metal-poor giants for moderate-resolution spectroscopy with Anglo-Australian Telescope/AAOmega. We used those data to select three confirmed metal-poor giants ([Fe/H]=-3.15, -2.56, -2.03) for follow-up high-resolution Magellan/Magellan Inamori Kyocera Echelle spectroscopy. A comprehensive orbit analysis using Gaia DR2 astrometry and our measured radial velocities confirms that these stars are tightly bound inner bulge stars. We determine the elemental abundances of each star and find high titanium and iron-peak abundances relative to iron in our most metal-poor star. We propose that the distinct abundance signature we detect is a product of nucleosynthesis in the Chandrasekhar-mass thermonuclear supernova of a CO white dwarf accreting from a helium star with a delay time of about 10Myr. Even though chemical evolution is expected to occur quickly in the bulge, the intense star formation in the core of the nascent Milky Way was apparently able to produce at least one Chandrasekhar-mass thermonuclear supernova progenitor before chemical evolution advanced beyond [Fe/H]~-3.
- ID:
- ivo://CDS.VizieR/J/A+A/533/A51
- Title:
- Abundances of 12 metal-rich barium stars
- Short Name:
- J/A+A/533/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determined the atmospheric parameters and abundance pattern for a sample of metal-rich barium stars. We used high resolution optical spectroscopy. Atmospheric parameters and abundances were determined using the local thermodynamic equilibrium atmosphere models of Kurucz and the spectral analysis code MOOG. We show that the stars have enhancement factors, [s/Fe], from 0.25 to 1.16. Their abundance pattern of Na, Al, {alpha}-elements and iron group elements as well as their kinematical properties are similar to the characteristics of the other metal rich and super metal-rich stars already analyzed. We conclude that metal rich barium stars do not belong to the bulge population. We also show that metal rich barium stars are useful targets to probe the s-process enrichment in high metallicity environments.
- ID:
- ivo://CDS.VizieR/J/A+A/512/A63
- Title:
- Abundances of M33 HII regions
- Short Name:
- J/A+A/512/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze the spatial distribution of metals in M33 using a new sample and literature data of HII regions, constraining a model of galactic chemical evolution with HII region and planetary nebula (PN) abundances. We consider chemical abundances of a new sample of HII regions complemented with previous literature data-sets. Supported by a uniform sample of nebular spectroscopic observations, we conclude that: i) the metallicity distribution in M33 is very complex, showing a central depression in metallicity probably due to observational bias; ii) the metallicity gradient in the disk of M33 has a slope of -0.037+/-0.009dex/kpc in the whole radial range up to ~8kpc, and -0.044+/-0.009dex/kpc excluding the central kpc; iii) there is a small evolution of the slope with time from the epoch of PN progenitor formation to the present-time. Description: Emission line fluxes, observed and dereddened of 33 HII regions are presented. Physical and chemical properties, such as electron temperatures and density, ionic and total chemical abundances of He, O, N, Ne, Ar, S, are derived.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A147
- Title:
- Abundances of microlensed bulge dwarf stars. V.
- Short Name:
- J/A+A/549/A147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a detailed elemental abundance analysis of dwarf stars in the Galactic bulge, based on high-resolution spectra that were obtained while the stars were optically magnified during gravitational microlensing events. The analysis method is the same as for a large sample of F and G dwarf stars in the Solar neighbourhood, enabling a fully differential comparison between the Bulge and the local stellar populations in the Galactic disc.
- ID:
- ivo://CDS.VizieR/J/A+A/605/A89
- Title:
- Abundances of microlensed Bulge dwarf stars. VI.
- Short Name:
- J/A+A/605/A89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a detailed elemental abundance analysis of dwarf stars in the Galactic bulge, based on high-resolution spectra that were obtained while the stars were optically magnified during gravitational microlensing events. The analysis method is the same as for a large sample of F and G dwarf stars in the Solar neighbourhood, enabling a fully differential comparison between the Bulge and the local stellar populations in the Galactic disc.
- ID:
- ivo://CDS.VizieR/J/A+A/499/737
- Title:
- Abundances of microlensed dwarf and subgiant stars
- Short Name:
- J/A+A/499/737
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed elemental abundance analysis of OGLE-2008-BLG-209S, the source star of a new microlensing event towards the Bulge, for which we obtained a high-resolution spectrum with the MIKE spectrograph on the Magellan Clay telescope. We have performed four different analyses of OGLE-2008-BLG-209S. One method is identical to the one used for a large comparison sample of F and G dwarf stars, mainly thin and thick disc stars, in the Solar neighbourhood. We have also re-analysed three previous microlensed dwarf stars OGLE-2006-BLG-265S, MOA-2006-BLG-099S, and OGLE-2007-BLG-349S with the same method. This homogeneous data set, although small, enables a direct comparison between the different stellar populations.
- ID:
- ivo://CDS.VizieR/J/A+A/533/A134
- Title:
- Abundances of microlensed stars in the Bulge
- Short Name:
- J/A+A/533/A134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a detailed elemental abundance analysis of dwarf stars in the Galactic bulge, based on high-resolution spectra that were obtained while the stars were optically magnified during gravitational microlensing events. The analysis method is the same as for a large sample of F and G dwarf stars in the Solar neighbourhood, enabling a fully differential comparison between the Bulge and the local stellar populations in the Galactic disc.
- ID:
- ivo://CDS.VizieR/J/A+A/512/A41
- Title:
- Abundances of microlensed stars in the Bulge
- Short Name:
- J/A+A/512/A41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a detailed elemental abundance analysis of dwarf stars in the Galactic bulge, based on high-resolution spectra that were obtained while the stars were optically magnified during gravitational microlensing events. The analysis method is the same as for a large sample of F and G dwarf stars in the Solar neighbourhood, enabling a fully differential comparison between the Bulge and the local stellar populations in the Galactic disc.
- ID:
- ivo://CDS.VizieR/J/A+A/541/A15
- Title:
- Abundances of M22 subgiants
- Short Name:
- J/A+A/541/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an abundance analysis of 101 subgiant branch (SGB) stars in the globular cluster M22. Using low-resolution FLAMES/GIRAFFE spectra we have determined abundances of the neutron-capture strontium and barium and the light element carbon. With these data we explore relationships between the observed SGB photometric split in this cluster and two stellar groups characterized by different contents of iron, slow neutron-capture process (s-process) elements, and the {alpha} element calcium, which we previously discovered in M22's red-giant stars.
- ID:
- ivo://CDS.VizieR/J/A+AS/125/219
- Title:
- Abundances of mu Lep, 7 Sex, HR 4817 & 28 Her
- Short Name:
- J/A+AS/125/219
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Elemental abundances are derived for four sharp-lined stars, the Mercury-Manganese stars {mu} Lep, HR 4817, and 28 Her, and 7 Sex, a Population I star with Population II space motions, using REOSC echelle spectrograms obtained at CASLEO to extend previous studies. Comparisons with published equivalent widths indicate that the CASLEO scale is marginally larger than those of DAO Reticon and KPNO CCD spectra. The CASLEO spectrograms have improved the quality of the abundance determinations. New abundances are found for a few elements.
- ID:
- ivo://CDS.VizieR/J/AJ/147/131
- Title:
- Abundances of nearby late-type galaxies. I. Data
- Short Name:
- J/AJ/147/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the oxygen and nitrogen abundance distributions across the optical disks of 130 nearby late-type galaxies using around 3740 published spectra of HII regions. We use these data in order to provide homogeneous abundance determinations for all objects in the sample, including HII regions in which not all of the usual diagnostic lines were measured. Examining the relation between N and O abundances in these galaxies we find that the abundances in their centers and at their isophotal R_25_ disk radii follow the same relation. The variation in N/H at a given O/H is around 0.3dex. We suggest that the observed spread in N/H may be partly caused by the time delay between N and O enrichment and the different star formation histories in galaxies of different morphological types and dimensions. We study the correlations between the abundance properties (central O and N abundances, radial O and N gradients) of a galaxy and its morphological type and dimension.
- ID:
- ivo://CDS.VizieR/J/MNRAS/382/553
- Title:
- Abundances of nearby red clump giants
- Short Name:
- J/MNRAS/382/553
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on the analysis of high-resolution spectra with a high signal-to-noise ratio, we have determined the abundances of the alpha-elements O, Si, Ca and Ti, the iron peak elements V, Fe and Ni, and the heavy element Ba without the consideration of non-local thermodynamic equilibrium (NLTE) effect and the light neutron-rich elements Na, Mg and Al with an NLTE analysis for 63 nearby red clump giants. Fe abundances cover a logarithmic range between 0.60 and +0.35 relative to solar. All abundance ratios with respect to Fe are similar to those found in the Sun. Hyperfine structure (HFS) was taken into account when calculating V lines. The difference in abundances obtained with and without HFS can be as large as 0.5 dex.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A126
- Title:
- Abundances of neutron-capture elements
- Short Name:
- J/A+A/649/A126
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The aim of this work is to determine abundances of neutron-capture elements for thin- and thick-disc F, G, and K stars in several selected sky fields near the North Ecliptic Pole and to compare the results with the Galactic chemical evolution models, to explore elemental gradients according to stellar ages, mean galactocentric distances, and maximum heights above the Galactic plane. The observational data were obtained with the 1.65 meter telescope at the Moletai Astronomical Observatory and a fibre-fed high-resolution spectrograph covering a full visible wavelength range (4000-8500{AA}). Elemental abundances were determined using a differential line-by-line spectrum synthesis using the TURBOSPECTRUM code with the MARCS stellar model atmospheres and accounting for the hyperfine-structure effects. Results. We determined abundances of Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, and Eu for 424 thin- and 82 thick-disc stars. The sample of thick-disc stars shows a clearly visible decrease of [Eu/Mg] with increasing metallicity compared to the thin-disc stars, bringing more evidences of different chemical evolution in these two Galactic components. Abundance correlation with age slopes for the investigated thin-disc stars are slightly negative for the majority of s-process dominated elements, while r-process dominated elements have positive correlations. Our sample of thin-disc stars with ages spanning from 0.1 to 9Gyrs gives the [Y/Mg]=0.022(+/-0.015)-0.027(+/-0.003)/age[Gyr] relation. However, for the thick-disc stars, when taking into account also data from other studies, we found that [Y/Mg] cannot serve as an age indicator. The radial abundance-to-iron gradients in the thin disc are negligible for the s-process dominated elements and become positive for the r-process dominated elements, the vertical gradients are negative for the light s-process dominated elements and become positive for the r-process dominated elements. In the thick disc, the radial abundance-to-iron slopes are negligible and the vertical ones are predominantly negative.
- ID:
- ivo://CDS.VizieR/J/ApJ/857/74
- Title:
- Abundances of 7 new member stars in Tucana II
- Short Name:
- J/ApJ/857/74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present chemical abundance measurements for seven stars with metallicities ranging from [Fe/H]=-3.3 to [Fe/H]=-2.4 in the TucanaII ultra-faint dwarf galaxy (UFD), based on high-resolution spectra obtained with the MIKE spectrograph on the 6.5m Magellan-Clay Telescope. For three stars, we present detailed chemical abundances for the first time. Of those, two stars are newly discovered members of Tucana II and were selected as probable members from deep narrowband photometry of the Tucana II UFD taken with the SkyMapper telescope. This result demonstrates the potential for photometrically identifying members of dwarf galaxy systems based on chemical composition. One new star was selected from the membership catalog of Walker+ (2016, J/ApJ/819/53). The other four stars in our sample have been reanalyzed, following additional observations. Overall, six stars have chemical abundances that are characteristic of the UFD stellar population. The seventh star shows chemical abundances that are discrepant from the other Tucana II members and an atypical, higher strontium abundance than what is expected for typical UFD stars. While unlikely, its strontium abundance raises the possibility that it may be a foreground metal-poor halo star with the same systemic velocity as Tucana II. If we were to exclude this star, Tucana II would satisfy the criteria to be a surviving first galaxy. Otherwise, this star implies that Tucana II has likely experienced somewhat extended chemical evolution.
- ID:
- ivo://CDS.VizieR/J/AJ/134/1216
- Title:
- Abundances of NGC 7142, 6939, and IC 4756 stars
- Short Name:
- J/AJ/134/1216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of echelle spectra of stars in three open clusters obtained with the Hydra multiobject spectrograph on the WIYN 3.5m telescope. Abundances of Fe, O, Si, Ca, Na, Al, and Ni have been determined via equivalent width analysis and spectrum synthesis. Mean abundances for each cluster are compared to those of previous studies and of other clusters in the literature, with emphasis on exploring the enhancements of Na and Al seen in many open clusters. All three clusters show enhanced values of [Na/Fe] and [Al/Fe], while the abundances of Fe, O, Si, and Ca are consistent with their ages and locations in the Galactic disk.
- ID:
- ivo://CDS.VizieR/J/A+A/431/933
- Title:
- Abundances of NGC 7789 evolved stars
- Short Name:
- J/A+A/431/933
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution spectra of six giants and three core-helium-burning "clump" stars in the open cluster NGC 7789 have been obtained with the SOFIN spectrograph on the Nordic Optical Telescope to investigate abundances of up to 20 chemical elements. Abundances of carbon were studied using the C_2_ Swan (0, 1) band head at 5635.5{AA}. The wavelength interval 7980-8130{AA} with strong CN features was analysed in order to determine nitrogen abundances and ^12^C/^13^C isotope ratios. The oxygen abundances were determined from the [O I] line at 6300{AA}.
- ID:
- ivo://CDS.VizieR/J/ApJ/824/73
- Title:
- Abundances of NGC 6362 member stars
- Short Name:
- J/ApJ/824/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first measure of Fe and Na abundances in NGC 6362, a low-mass globular cluster (GC) where first- and second-generation stars are fully spatially mixed. A total of 160 member stars (along the red giant branch (RGB) and the red horizontal branch (RHB)) were observed with the multi-object spectrograph FLAMES at the Very Large Telescope. We find that the cluster has an iron abundance of [Fe/H]=-1.09+/-0.01dex, without evidence of intrinsic dispersion. On the other hand, the [Na/Fe] distribution turns out to be intrinsically broad and bimodal. The Na-poor and Na-rich stars populate, respectively, the bluest and the reddest RGBs detected in the color-magnitude diagrams including the U filter. The RGB is composed of a mixture of first- and second-generation stars in a similar proportion, while almost all the RHB stars belong to the first cluster generation. To date, NGC 6362 is the least massive GC where both the photometric and spectroscopic signatures of multiple populations have been detected.
- ID:
- ivo://CDS.VizieR/J/A+A/565/A23
- Title:
- Abundances of NGC5897 red giants
- Short Name:
- J/A+A/565/A23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report for the first time on the chemical composition of the halo cluster NGC 5897 (R_{sun}_=12.5kpc), based on chemical abundance ratios for 27 {alpha}-, iron-peak, and neutron-capture elements in seven red giants. From our high-resolution, high signal-to-noise spectra obtained with theMagellan/MIKE spectrograph, we find a mean iron abundance from the neutral species of [Fe/H]=-2.04+/-0.01(stat.)+/-0.15(sys.), which is more metal-poor than implied by previous photometric and low-resolution spectroscopic studies. NGC 5897 is {alpha}-enhanced (to 0.34+/-0.01dex) and shows Fe-peak element ratios typical of other (metal-poor) halo globular clusters (GCs) with no overall, significant abundance spreads in iron nor in any other heavy element.
- ID:
- ivo://CDS.VizieR/J/A+A/490/625
- Title:
- Abundances of NGC 6121 red giants
- Short Name:
- J/A+A/490/625
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present abundance analysis based on high resolution spectra of 105 isolated red giant branch (RGB) stars in the Galactic Globular Cluster NGC 6121 (M4). The data have been collected with FLAMES+UVES, at the ESO/VLT@UT2 telescope. Spectroscopic data were coupled with high precision wide-field UBVI_C photometry from WFI@2.2m telescope and infrared JHK photometry from 2MASS. We derived an average [Fe/H]=-1.07+/-0.01, and an {alpha} enhancement of [{alpha}/Fe]=+0.39+/-0.05dex (internal errors). We confirm the presence of an extended Na-O anticorrelation, and find two distinct groups of stars with significantly different Na and O content. We find no evidence of a Mg-Al anticorrelation. By coupling our results with previous studies on the CN band strength, we find that the CN strong stars have higher Na and Al content and are more O depleted than the CN weak ones. The two groups of Na-rich, CN-strong and Na-poor, CN-weak stars populate two different regions along the RGB. In the U vs. U-B color magnitude diagram the RGB spread is present from the base of the RGB to the RGB-tip. Apparently, both spectroscopic and photometric results imply the presence of two stellar populations in M4. We briefly discuss the possible origin of these populations.
- ID:
- ivo://CDS.VizieR/J/A+A/279/567
- Title:
- Abundances of non-type I PNe in LMC
- Short Name:
- J/A+A/279/567
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopic observations, plasma diagnostics and chemical composition of 15 non-type I planetary nebulae (PNe) in the Large Magellanic Cloud (LMC) are reported. Abundances of He, O, N, S, and Ar are determined and compared with recently obtained data for nebulae both in the Magellanic Clouds and in the Galaxy.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1694
- Title:
- Abundances of non-variable red and blue HB stars
- Short Name:
- J/AJ/140/1694
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new detailed abundance study of field red horizontal branch (RHB) and blue horizontal branch (BHB) non-variable stars. High resolution and high signal-to-noise ratio echelle spectra of 11 RHB and 12 BHB were obtained with the McDonald 2.7m telescope, and the RHB sample was augmented by reanalysis of spectra of 25 stars from a recent survey. We derived stellar atmospheric parameters based on spectroscopic constraints and computed relative abundance ratios for 24 species of 19 elements.
- ID:
- ivo://CDS.VizieR/J/ApJ/660/1462
- Title:
- Abundances of ONC X-ray PMS stars
- Short Name:
- J/ApJ/660/1462
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Following the Chandra Orion Ultradeep Project (COUP) observation, we have studied the chemical composition of the hot plasma in a sample of 146 X-ray-bright pre-main-sequence stars in the Orion Nebula Cluster (ONC). We report measurements of individual element abundances for a subsample of 86 slightly absorbed and bright X-ray sources, using low-resolution X-ray spectra obtained from the Chandra ACIS instrument.
- ID:
- ivo://CDS.VizieR/J/MNRAS/428/2321
- Title:
- Abundances of open cluster stars
- Short Name:
- J/MNRAS/428/2321
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first generation of large-scale chemical tagging surveys, in particular the High Efficiency and Resolution Multi-Element Spectrograph (HERMES)/Galactic Archaeology with HERMES million star survey, promises to vastly expand our understanding of the chemical and dynamical evolution of the Galaxy. This, however, is contingent on our ability to confidently perform chemical tagging on such a large data set. Chemical homogeneity has been observed across a range of elements within several Galactic open clusters, yet the level to which this is the case globally, and particularly in comparison to the scatter across clusters themselves, is not well understood. The patterns of elements in coeval cluster members, occupying a complex chemical abundance space, are rooted in the evolution, ultimately the nature of the very late stages, of early generations of stars. The current astrophysical models of such stages are not yet sufficient to explain all observations, combining with our significant gaps in the understanding of star formation, makes this a difficult arena to tackle theoretically. Here, we describe a robust pair-wise metric used to gauge the chemical difference between two stellar components. This metric is then applied to a data base of high-resolution literature abundance sources to derive a function describing the probability that two stars are of common evolutionary origin. With this cluster probability function, it will be possible to report a confidence, grounded in empirical observational evidence, with which clusters are detected, independent of the group finding methods. This formulation is also used to probe the role of chemical dimensionality, and that of individual chemical species, on the ability of chemical tagging to differentiate coeval groups of stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/655/1046
- Title:
- Abundances of {phi} Her
- Short Name:
- J/ApJ/655/1046
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of the mercury-manganese star phi Her with the Navy Prototype Optical Interferometer (NPOI) conclusively reveal the previously unseen companion in this single-lined binary system. The NPOI data were used to predict a spectral type of A8 V for the secondary star phi Her B. This prediction was subsequently confirmed by spectroscopic observations obtained at the Dominion Astrophysical Observatory. phi Her B is rotating at 50+/-3km/s, in contrast to the 8 km/s lines of phi Her A. Recognizing the lines from the secondary permits one to separate them from those of the primary. The abundance analysis of phi Her A shows an abundance pattern similar to those of other HgMn stars, with Al being very under-abundant and Sc, Cr, Mn, Zn, Ga, Sr, Y, Zr, Ba, Ce, and Hg being very overabundant.
- ID:
- ivo://CDS.VizieR/J/MNRAS/496/2422
- Title:
- Abundances of 42 Pisces-Eridanus stream stars
- Short Name:
- J/MNRAS/496/2422
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recently, a new cylindrical-shaped stream of stars, up to 700pc long, was discovered hiding in the Galactic disk using kinematic data enabled by the Gaia mission. This curious stream of stars, dubbed the Pisces-Eridanus stream, was initially thought to be as old as 1Gyr, yet its stars shared a rotation period distribution consistent with the 120-Myr-old Pleiades cluster. In this work, we explore the detailed chemical nature of this stellar stream. We carried out high-resolution spectroscopic follow-up of 42 Pisces-Eridanus stream stars using McDonald Observatory, and combined these data with information for 40 members observed with the low-resolution LAMOST spectroscopic survey. Together, these data enabled us to measure the abundance distribution of light/odd-Z (Li, C, Na, Al, Sc, V), {alpha} (Mg, Si, Ca, Ti), Fe-peak (Cr, Mn, Fe, Co, Ni, Zn), and neutron capture (Sr, Y, Zr, Ba, La, Nd, Eu) elements across the Pisces-Eridanus stream. We find that the stream is (1) near solar metallicity with [Fe/H] = -0.03 dex and (2) has a metallicity spread of 0.07 dex (or 0.04 dex when removing outliers). We also find that (3) the abundance of Li indicates that Pisces-Eridanus is ~120Myr old, consistent with the gyrochronology result. We find that (4) the stream has a [X/Fe] abundance spreads of 0.06<{sigma}_[X/Fe]_<0.20dex in most elements, and (5) no significant abundance gradients across its major axis except a potentially weak gradient in [Si/Fe]. These results together show that the Pisces-Eridanus stream is a uniquely close, young, chemically interesting laboratory for testing our understanding of star and planet formation.
- ID:
- ivo://CDS.VizieR/J/A+A/552/A12
- Title:
- Abundances of PNe in NGC 300
- Short Name:
- J/A+A/552/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained deep spectroscopy of 26 planetary nebulae (PNe) and 9 compact HII regions in the nearby spiral galaxy NGC 300, and analyzed them together with the giant HII regions observed by Bresolin et al. (2009ApJ...700..309B). We have determined the physical properties of all those objects and their content in He, N, O, Ne, S and Ar in a consistent way. We find that compact HII regions have abundances similar to those of giant HII regions, while PNe have systematically larger N/O ratios and similar Ne/O and Ar/O ratios. We demonstrate that this nitrogen enhancement in PNe cannot be due to second dredge-up in the progenitor stars, since their initial masses are around 2-2.5M_{sun}_. An extra mixing process is required, perhaps be driven by rotation. Concerning the radial abundance distribution, PNe behave differently from HII regions: In the central parts, they show an average O/H smaller by 0.15dex. Their abundance dispersion at any galactocentric radius is significantly larger than for HII regions and many of them have O/H values higher than HII regions at the same galactocentric distance, suggesting that oxygen production in the PN progenitors in NGC 300 is common. PN abundance gradients in O/H, Ne/H and Ar/He are significantly shallower than those of HII regions. We argue that this indicates a steepening of the metallicity gradient in NGC 300 during the last Gr, rather than the effect of radial stellar motions.
- ID:
- ivo://CDS.VizieR/J/A+A/380/300
- Title:
- Abundances of PN towards Galactic bulge
- Short Name:
- J/A+A/380/300
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work we report spectrophotometric observations of a planetary nebula sample towards the galactic bulge. A total of 45 PNe was observed and their physical parameters (electron density and temperature) were derived. Ionic abundances were calculated using a three-level atom model and abundances were derived through ionisation correction factors. Results show low abundance objects at high galactic latitudes, indicating a possible vertical gradient inside the bulge. A few objects with low N/O ratio were found, which could have originated from old, low mass progenitors.
- ID:
- ivo://CDS.VizieR/J/A+A/490/777
- Title:
- Abundances of Population II stars in NGC 6397
- Short Name:
- J/A+A/490/777
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Evolutionary trends in the surface abundances of heavier elements have recently been identified in the globular cluster NGC 6397 ([Fe/H]=-2), indicating the operation of atomic diffusion in these stars. Such trends constitute important constraints for the extent to which diffusion modifies the internal structure and surface abundances of solar-type, metal-poor stars. We perform an independent check of the reality and size of abundance variations within this metal-poor globular cluster. Observational data covering a large stellar sample, located between the cluster turn-off point and the base of the red giant branch, are homogeneously analysed. The spectroscopic data were obtained with the medium-high resolution spectrograph FLAMES/GIRAFFE on VLT-UT2 (R~27000). We derive independent effective-temperature scales from profile fitting of Balmer lines and by applying colour-Teff calibrations to Stroemgren uvby and broad-band BVI photometry. An automated spectral analysis code is used together with a grid of MARCS model atmospheres to derive stellar surface abundances of Mg, Ca, Ti, and Fe.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/137
- Title:
- Abundances of red clump & RGB stars with APOGEE
- Short Name:
- J/ApJ/872/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Internal mixing on the giant branch is an important process which affects the evolution of stars and the chemical evolution of the galaxy. While several mechanisms have been proposed to explain this mixing, better empirical constraints are necessary. Here, we use [C/N] abundances in 26097 evolved stars from the SDSS-IV/APOGEE-2 DR14 to trace mixing and extra mixing in old field giants with -1.7<[Fe/H]<0.1. We show that the APOGEE [C/N] ratios before any dredge-up occurs are metallicity dependent, but that the change in [C/N] at the first dredge-up is metallicity independent for stars above [Fe/H]~-1. We identify the position of the red giant branch (RGB) bump as a function of metallicity, note that a metallicity-dependent extra mixing episode takes place for low-metallicity stars ([Fe/H]{<}-0.4) 0.14dex in logg above the bump, and confirm that this extra mixing is stronger at low metallicity, reaching {Delta}[C/N]=0.58dex at [Fe/H]=-1.4. We show evidence for further extra mixing on the upper giant branch, well above the bump, among the stars with [Fe/H]{<}-1.0. This upper giant branch mixing is stronger in the more metal-poor stars, reaching 0.38 dex in [C/N] for each 1.0dex in logg. The APOGEE [C/N] ratios for red clump (RC) stars are significantly higher than for stars at the tip of the RGB, suggesting additional mixing processes occur during the helium flash or that unknown abundance zero points for C and N may exist among the RC sample. Finally, because of extra mixing, we note that current empirical calibrations between [C/N] ratios and ages cannot be naively extrapolated for use in low-metallicity stars specifically for those above the bump in the luminosity function.
- ID:
- ivo://CDS.VizieR/J/ApJ/763/61
- Title:
- Abundances of 7 red giant members of BootesI
- Short Name:
- J/ApJ/763/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a double-blind analysis of high-dispersion spectra of seven red giant members of the Bootes I ultrafaint dwarf spheroidal galaxy, complemented with re-analysis of a similar spectrum of an eighth-member star. The stars cover [Fe/H] from -3.7 to -1.9 and include a CEMP-no star with [Fe/H]=-3.33. We conclude from our chemical abundance data that Bootes I has evolved as a self-enriching star-forming system, from essentially primordial initial abundances. This allows us uniquely to investigate the place of CEMP-no stars in a chemically evolving system, in addition to limiting the timescale of star formation. The elemental abundances are formally consistent with a halo-like distribution, with enhanced mean [{alpha}/Fe] and small scatter about the mean. This is in accord with the high-mass stellar initial mass function in this low-stellar-density, low-metallicity system being indistinguishable from the present-day solar neighborhood value. There is a non-significant hint of a decline in [{alpha}/Fe] with [Fe/H]; together with the low scatter, this requires low star formation rates, allowing time for supernova ejecta to be mixed over the large spatial scales of interest. One star has very high [Ti/Fe], but we do not confirm a previously published high value of [Mg/Fe] for another star. We discuss the existence of CEMP-no stars, and the absence of any stars with lower CEMP-no enhancements at higher [Fe/H], a situation that is consistent with knowledge of CEMP-no stars in the Galactic field. We show that this observation requires there be two enrichment paths at very low metallicities: CEMP-no and "carbon-normal."