- ID:
- ivo://CDS.VizieR/J/ApJ/890/71
- Title:
- 5100{AA} continuum & emission lines LCs of PG2130+099
- Short Name:
- J/ApJ/890/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As one of the most interesting Seyfert 1 galaxies, PG 2130+099 has been the target of several reverberation mapping (RM) campaigns over the years. However, its measured broad H{beta} line responses have been inconsistent, with time lags of ~200days, ~25days, and ~10days being reported for different epochs while its optical luminosity changed no more than 40%. To investigate this issue, we conducted a new RM-campaign with homogenous and high cadence (about ~3days) for two years during 2017-2019 to measure the kinematics and structure of the ionized gas. We successfully detected time lags of broad H{beta}, HeII, HeI, and FeII lines with respect to the varying 5100{AA} continuum, revealing a stratified structure that is likely virialized with Keplerian kinematics in the first year of observations, but an inflow kinematics of the broad-line region from the second year. With a central black hole mass of 0.97_-0.18_^+0.15^x10^7^M_{sun}_, PG2130+099 has an accretion rate of 10^2.1+/-0.5^L_Edd_c^-2^, where L_Edd_ is the Eddington luminosity and c is speed of light, implying that it is a super-Eddington accretor and likely possesses a slim, rather than thin, accretion disk. The fast changes of the ionization structures of the three broad lines remain puzzling.
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- ID:
- ivo://CDS.VizieR/J/ApJ/850/34
- Title:
- 3000-25000{AA} spectroscopy of nearby M dwarfs
- Short Name:
- J/ApJ/850/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent studies of the stellar population in the solar neighborhood (<20pc) suggest that there are undetected white dwarfs (WDs) in multiple systems with main-sequence companions. Detecting these hidden stars and obtaining a more complete census of nearby WDs is important for our understanding of stellar and galactic evolution, as well as the study of explosive phenomena. In an attempt to uncover these hidden WDs, we present intermediate resolution spectroscopy over the wavelength range of 3000-25000{AA} of 101 nearby M dwarfs (dMs), observed with the Very Large Telescope X-Shooter spectrograph. For each star we search for a hot component superimposed on the dM spectrum. X-Shooter has excellent blue sensitivity and thus can reveal a faint hot WD despite the brightness of its red companion. Visual examination shows no clear evidence of a WD in any of the spectra. We place upper limits on the effective temperatures of WDs that may still be hiding by fitting dM templates to the spectra and modeling the WD spectra. On average our survey is sensitive to WDs hotter than about 5300K. This suggests that the frequency of WD companions of Teff>~5300K with separation of the order of <~50 au among the local dM population is <3% at the 95% confidence level.
- ID:
- ivo://CDS.VizieR/II/336
- Title:
- AAVSO Photometric All Sky Survey (APASS) DR9
- Short Name:
- II/336
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The AAVSO Photometric All Sky Survey (APASS) project is designed to bridge the gap between the shallow Tycho2 two-bandpass photometric catalog that is complete to V=11 and the deeper, but less spatially-complete catalogs like SDSS or PanSTARRS. It can be used for calibration of a specific field; for obtaining spectral information about single sources, determining reddening in a small area of the sky; or even obtaining current-epoch astrometry for rapidly moving objects. The survey is being performed at two locations: near Weed, New Mexico in the Northern Hemisphere; and at CTIO in the Southern Hemisphere. Each site consists of dual bore-sighted 20cm telescopes on a single mount, designed to obtain two bandpasses of information simultaneously. Each telescope covers 9 square degrees of sky with 2.5arcsec pixels, with the main survey taken with B,V,g',r',i' filters and covering the magnitude range 10<V<17. A bright extension is underway, saturating at V=7 and extending the wavelength coverage from u' to Y. The current catalog is Data Release 9 and contains approximately 62 million stars. The American Association of Variable Star Observers is responsible for the overall management of the survey; a team of professional astronomers participate in the data analysis. The project was initially funded by the Robert Martin Ayers Sciences Fund, with a follow-on grant from the National Science Foundation.
- ID:
- ivo://CDS.VizieR/J/A+AS/106/373
- Title:
- AB And UBV photometry
- Short Name:
- J/A+AS/106/373
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/607/A131
- Title:
- Abell 520 galaxies redshifts
- Short Name:
- J/A+A/607/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mergers of galaxy clusters are the most energetic events in the universe after the Big Bang. An ever increasing fraction of local clusters exhibit signs of recent or past mergers. Our goal is to probe how these mergers affect the evolution and content of their member galaxies. We specifically aim to answer the following questions: Is the quenching of star formation in merging clusters enhanced when compared with relaxed clusters? Is the quenching accompanied by a (short lived) burst of star formation? We obtained optical spectroscopy of $>400$ galaxies in the field of the merging cluster Abell 520. We combine these observations with archival data to get a comprehensive picture of the state of star formation in the members of this merging cluster. Finally, we compare these observations with a control sample of 10 non-merging clusters at the same redshift from The Arizona Cluster Redshift Survey (ACReS). We split the member galaxies in passive, star forming or recently quenched depending on their spectra. The core of the merger shows a decreased fraction of star-forming galaxies compared to clusters in the non-merging sample. This region, dominated by passive galaxies, is extended along the axis of the merger. We find evidence of rapid quenching of the galaxies during the core passage with no signs of a star burst on the time scales of the merger. Additionally, we report the tentative discovery of an infalling group along the main filament feeding the merger, currently at ~2.5Mpc from the merger centre. This group contains a high fraction of star forming galaxies as well as ~2/3 of all the recently quenched galaxies in our survey.
- ID:
- ivo://CDS.VizieR/J/MNRAS/423/256
- Title:
- Abell 1689 imaging and spectroscopy
- Short Name:
- J/MNRAS/423/256
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present imaging and spectroscopy of Abell 1689 (z=0.183) from the Gemini multi-object spectrograph (GMOS) on the Gemini North telescope and the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST). We measure integrated photometry from the GMOS g' and r' images (for 531 galaxies) and surface photometry from the HSTF625W image (for 43 galaxies) as well as velocities and velocity dispersions from the GMOS spectra (for 71 galaxies). We construct the Kormendy, Faber-Jackson and colour-magnitude relations for early-type galaxies in Abell 1689 using these data and compare them to those of the Coma cluster.
- ID:
- ivo://CDS.VizieR/J/A+A/602/A20
- Title:
- Abell 315 spectroscopic dataset
- Short Name:
- J/A+A/602/A20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Determination of cluster masses is a fundamental tool for cosmology. Comparing mass estimates obtained by different probes allows to understand possible systematic uncertainties. Aims. The cluster Abell 315 is an interesting test case, since it has been claimed to be underluminous in X-ray for its mass (determined via kinematics and weak lensing). We have undertaken new spectroscopic observations with the aim of improving the cluster mass estimate, using the distribution of galaxies in projected phase space. We identified cluster members in our new spectroscopic sample. We estimated the cluster mass from the projected phase-space distribution of cluster members using the MAMPOSSt method. In doing this estimate we took into account the presence of substructures that we were able to identify. We identify several cluster substructures. The main two have an overlapping spatial distribution, suggesting a (past or ongoing) collision along the line-of-sight. After accounting for the presence of substructures, the mass estimate of Abell 315 from 14 kinematics is reduced by a factor 4, down to M_200_=0.8_-0.4_^+0.6^10+14M_{sun}_. We also find evidence that the cluster mass concentration is unusually low, c_200_=r_200_/r_-2_<1. Using our new estimate of c200 we revise the weak lensing mass estimate down to M_200_=1.8_-0.9_^+1.7^10+14M_{sun}_. Our new mass estimates are in agreement with that derived from the cluster X-ray luminosity via a scaling relation, M_200_=0.9+/-0.2*10^14^M_{sun}_. Abell 315 no longer belongs to the class of X-ray underluminous clusters. Its mass estimate was inflated by the presence of an undetected subcluster in collision with the main cluster. Whether the presence of undetected line-of-sight structures can be a general explanation for all X-ray underluminous clusters remains to be explored using a statistically significant sample.
- ID:
- ivo://CDS.VizieR/J/MNRAS/468/703
- Title:
- Abell 168 ultra-diffuse galaxies distribution
- Short Name:
- J/MNRAS/468/703
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Taking advantage of the Sloan Digital Sky Survey Stripe82 data, we have explored the spatial distribution of ultra-diffuse galaxies (UDGs) within an area of 8x8Mpc^2^ centred around the galaxy cluster Abell 168 (z=0.045). This intermediate massive cluster ({sigma}=550km/s) is surrounded by a complex large-scale structure. Our work confirms the presence of UDGs in the cluster and in the large-scale structure that surrounds it, and it is the first detection of UDGs outside clusters. Approximately 50 per cent of the UDGs analysed in the selected area inhabit the cluster region (~11+/-5 per cent in the core and ~39+/-9 per cent in the outskirts), whereas the remaining UDGs are found outside the main cluster structure (~50+/-11 per cent). The colours and the spatial distribution of the UDGs within this large-scale structure are more similar to dwarf galaxies than to L* galaxies, suggesting that most UDGs could be bona fide dwarf galaxies.
- ID:
- ivo://CDS.VizieR/J/AN/326/321
- Title:
- Absolute magnitudes for late-type dwarfs
- Short Name:
- J/AN/326/321
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new formula for absolute magnitude determination for late-type dwarf stars as a function of (g-r) and (r-i) for Sloan photometry (as defined by Abazajian et al., 2003AJ....126.2081A). The absolute magnitudes estimated by this approach are brighter than those estimated by colour-magnitude diagrams, and they reduce the luminosity function rather close to the luminosity function of Hipparcos.
- ID:
- ivo://CDS.VizieR/J/AJ/124/601
- Title:
- Absolute positions and proper motions in NGC 188
- Short Name:
- J/AJ/124/601
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The field of direct imaging is experiencing a considerable growth in the number of available CCD mosaic imagers, especially on large telescopes. To fully exploit the astrometric potential of these imaging devices, we develop a technique, utilizing an astrometric standard, for precision transformation of pixel coordinates into a global coordinate system. We have constructed a new astrometric standard set of 1863 stars in the field of NGC 188 to derive the CCD chip constants for the NOAO CCD Mosaic Imager. The multiple-epoch data on the Mosaic's metrics indicate that this CCD mosaic device may have experienced a one-time nonelastic expansion. We also present a new determination of the pixel scale and the optical field angle distortion constants for the KPNO Mayall 4 m telescope prime focus field corrector. To establish a reliable history of the CCD mosaic imager metrics for current and potential future astrometric applications, we recommend obtaining astrometric calibrations for CCD mosaic imagers on a regular basis. Apart from mechanical positioning of the CCD mosaic camera on the telescope, noticeable changes in the thermal environment of CCD mosaic chips should also prompt new astrometric calibrations. It is shown that, following all precautions, the NOAO CCD Mosaic Imager can produce excellent astrometric results on the Mayall 4 m telescope.
- ID:
- ivo://CDS.VizieR/J/ApJ/691/1400
- Title:
- Absolute properties of CM Dra
- Short Name:
- J/ApJ/691/1400
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present a complete reanalysis of the eclipsing systems, CM Dra, composed of two dM4.5 stars. New and existing light curves as well as a radial velocity curve are modeled to measure the physical properties of both components. The masses and radii determined for the components of CM Dra are M1=0.2310+/-0.0009M_{sun}_, M2=0.2141+/-0.0010M_{sun}_, R1=0.2534+/-0.0019R_{sun}_, and R2=0.2396+/-0.0015R_{sun}_. With relative uncertainties well below the 1% level, these values constitute the most accurate properties to date for fully convective stars.
- ID:
- ivo://CDS.VizieR/J/AJ/155/213
- Title:
- Absolute reflectance & new calibration site of the Moon
- Short Name:
- J/AJ/155/213
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- How bright the Moon is forms a simple but fundamental and important question. Although numerous efforts have been made to answer this question such as use of sophisticated electro-optical measurements and suggestions for calibration sites, the answer is still debated. An in situ measurement with a calibration panel on the surface of the Moon is crucial for obtaining the accurate absolute reflectance and resolving the debate. China's Chang'E-3 (CE-3) "Yutu" rover accomplished this type of measurement using the Visible-Near Infrared Spectrometer (VNIS). The measurements of the VNIS, which were at large emission and phase angles, complement existing measurements for the range of photometric geometry. The in situ reflectance shows that the CE-3 landing site is very dark with an average reflectance of 3.86% in the visible bands. The results are compared with recent mission instruments: the Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC), the Spectral Profiler (SP) on board the SELENE, the Moon Mineralogy Mapper (M^3^) on board the Chandrayaan-1, and the Chang'E-1 Interference Imaging Spectrometer (IIM). The differences in the measurements of these instruments are very large and indicate inherent differences in their absolute calibration. The M^3^ and IIM measurements are smaller than LROC WAC and SP, and the VNIS measurement falls between these two pairs. When using the Moon as a radiance source for the on-orbit calibration of spacecraft instruments, one should be cautious about the data. We propose that the CE-3 landing site, a young and homogeneous surface, should serve as the new calibration site.
- ID:
- ivo://CDS.VizieR/J/AJ/161/285
- Title:
- Absorption & emission lines and RVel for vA 351
- Short Name:
- J/AJ/161/285
- Date:
- 08 Mar 2022
- Publisher:
- CDS
- Description:
- We extend results first announced by Franz et al., that identified vA351=H346 in the Hyades as a multiple star system containing a white dwarf. With Hubble Space Telescope Fine Guidance Sensor fringe tracking and scanning, and more recent speckle observations, all spanning 20.7years, we establish a parallax, relative orbit, and mass fraction for two components, with a period, P=2.70yr and total mass 2.1M{sun}. With ground-based radial velocities from the McDonald Observatory Otto Struve 2.1m Telescope Sandiford Spectrograph, and Center for Astrophysics Digital Speedometers, spanning 37 years, we find that component B consists of BC, two M-dwarf stars orbiting with a very short period (P_BC_=0.749days), having a mass ratio M_C_/M_B_=0.95. We confirm that the total mass of the system can only be reconciled with the distance and component photometry by including a fainter, higher-mass component. The quadruple system consists of three M dwarfs (A, B, C) and one white dwarf (D). We determine individual M-dwarf masses M_A_=0.53{+/-}0.10M{sun}, M_B_=0.43{+/-}0.04M{sun}, and M_C_=0.41{+/-}0.04M{sun}. The white dwarf mass, 0.54{+/-}0.04M{sun}, comes from cooling models, an assumed Hyades age of 670Myr, and consistency with all previous and derived astrometric, photometric, and radial velocity results. Velocities from H{alpha} and HeI emission lines confirm the BC period derived from absorption lines, with similar (HeI) and higher (H{alpha}) velocity amplitudes. We ascribe the larger H{alpha} amplitude to emission from a region each component shadows from the other, depending on the line of sight.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/11
- Title:
- Absorption features in SDSS. I. MgII abs. doublets
- Short Name:
- J/ApJS/235/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the SDSS spectra of quasars included in the DR7Q or DR12Q catalogs, we search for MgII{lambda}{lambda}2796,2803 narrow absorption doublets in the spectra data around MgII{lambda}2798 emission lines. We obtain 17316 MgII doublets, within the redshift range of 0.3299<=z_abs_<=2.5663. We find that a velocity offset of {upsilon}_r_<6000km/s is a safe boundary to constrain the vast majority of associated Mg ii systems, although we find some doublets at {upsilon}_r_>6000km/s. If associated Mg ii absorbers are defined by {upsilon}_r_<6000km/s, ~33.3% of the absorbers are supposed to be contaminants of intervening systems. Removing the 33.3% contaminants, ~4.5% of the quasars present at least one associated MgII system with W_r_^{lambda}2796^>=0.2{AA}. The fraction of associated MgII systems with high-velocity outflows correlates with the average luminosities of their central quasars, indicating a relationship between outflows and the quasar feedback power. The {upsilon}_r_ distribution of the outflow MgII absorbers is peaked at 1023km/s, which is smaller than the corresponding value of the outflow CIV absorbers. The redshift number density evolution of absorbers (dn/dz) limited by {upsilon}_r_{>}-3000km/s differs from that of absorbers constrained by {upsilon}_r_>2000km/s. Absorbers limited by {upsilon}_r_>2000km/s and higher values exhibit profiles similar to dn/dz. In addition, the dn/dz is smaller when absorbers are constrained with larger {upsilon}_r_. The distributions of equivalent widths, and the ratio of W_r_^{lambda}2796^/W_r_^{lambda}2803^, are the same for associated and intervening systems, and independent of quasar luminosity.
- ID:
- ivo://CDS.VizieR/J/ApJ/847/127
- Title:
- Abundance analyses of V652 Her and HD 144941
- Short Name:
- J/ApJ/847/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical high-resolution spectra of V652 Her and HD 144941, the two extreme helium stars with exceptionally low C/He ratios, have been subjected to a non-LTE abundance analysis using the tools TLUSTY and SYNSPEC. Defining atmospheric parameters were obtained from a grid of non-LTE atmospheres and a variety of spectroscopic indicators including HeI and HeII line profiles, and the ionization equilibrium of ion pairs such as CII/CIII and NII/NIII. The various indicators provide a consistent set of atmospheric parameters: Teff=25000+/-300K, logg=3.10+/-0.12(cgs), and {xi}=13+/-2km/s are provided for V652 Her, and Teff=22000+/-600K, logg=3.45+/-0.15(cgs), and {xi}=10km/s are provided for HD 144941. In contrast to the non-LTE analyses, the LTE analyses-LTE atmospheres and an LTE line analysis-with the available indicators do not provide a consistent set of atmospheric parameters. The principal non-LTE effect on the elemental abundances is on the neon abundance. It is generally considered that these extreme helium stars with their very low C/He ratio result from the merger of two helium white dwarfs. Indeed, the derived composition of V652 Her is in excellent agreement with predictions by Zhang & Jeffery (2012MNRAS.419..452Z), who model the slow merger of helium white dwarfs; a slow merger results in the merged star having the composition of the accreted white dwarf. In the case of HD 144941, which appears to have evolved from metal-poor stars, a slow merger is incompatible with the observed composition but variations of the merger rate may account for the observed composition. More detailed theoretical studies of the merger of a pair of helium white dwarfs are to be encouraged.
- ID:
- ivo://CDS.VizieR/J/ApJ/865/129
- Title:
- Abundance analysis of HD 222925
- Short Name:
- J/ApJ/865/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed abundance analysis of the bright (V=9.02), metal-poor ([Fe/H]=-1.47+/-0.08) field red horizontal-branch star HD222925, which was observed as part of an ongoing survey by the R-Process Alliance. We calculate stellar parameters and derive abundances for 46 elements based on 901 lines examined in a high-resolution optical spectrum obtained using the Magellan Inamori Kyocera Echelle spectrograph. We detect 28 elements with 38<=Z<=90; their abundance pattern is a close match to the solar r-process component. The distinguishing characteristic of HD222925 is an extreme enhancement of r-process elements ([Eu/Fe]=+1.33+/-0.08, [Ba/Eu]=-0.78+/-0.10) in a moderately metal-poor star, so the abundance of r-process elements is the highest ([Eu/H]=-0.14+/-0.09) in any known r-process-enhanced star. The abundance ratios among lighter (Z<=30) elements are typical for metal-poor stars, indicating that production of these elements was dominated by normal Type II supernovae, with no discernible contributions from Type Ia supernovae or asymptotic giant branch stars. The chemical and kinematic properties of HD 222925 suggest it formed in a low-mass dwarf galaxy, which was enriched by a high-yield r-process event before being disrupted by interaction with the Milky Way.
- ID:
- ivo://CDS.VizieR/J/ApJ/838/90
- Title:
- Abundance analysis of 9 very metal-poor stars
- Short Name:
- J/ApJ/838/90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed a differential line-by-line chemical abundance analysis, ultimately relative to the Sun, of nine very metal-poor main-sequence (MS) halo stars, near [Fe/H]=-2dex. Our abundances range from -2.66<=[Fe/H]<=-1.40dex with conservative uncertainties of 0.07dex. We find an average [{alpha}/Fe]=0.34+/-0.09dex, typical of the Milky Way. While our spectroscopic atmosphere parameters provide good agreement with Hubble Space Telescope parallaxes, there is significant disagreement with temperature and gravity parameters indicated by observed colors and theoretical isochrones. Although a systematic underestimate of the stellar temperature by a few hundred degrees could explain this difference, it is not supported by current effective temperature studies and would create large uncertainties in the abundance determinations. Both 1D and <3D> hydrodynamical models combined with separate 1D non-LTE effects do not yet account for the atmospheres of real metal-poor MS stars, but a fully 3D non-LTE treatment may be able to explain the ionization imbalance found in this work.
- ID:
- ivo://CDS.VizieR/J/AJ/144/95
- Title:
- Abundance in stars of the outer galactic disk. IV.
- Short Name:
- J/AJ/144/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present radial velocities and chemical abundances for nine stars in the old, distant open clusters Be18, Be21, Be22, Be32, and PWM4. For Be18 and PWM4, these are the first chemical abundance measurements. Combining our data with literature results produces a compilation of some 68 chemical abundance measurements in 49 unique clusters. For this combined sample, we study the chemical abundances of open clusters as a function of distance, age, and metallicity. We confirm that the metallicity gradient in the outer disk is flatter than the gradient in the vicinity of the solar neighborhood. We also confirm that the open clusters in the outer disk are metal-poor with enhancements in the ratios [{alpha}/Fe] and perhaps [Eu/Fe]. All elements show negligible or small trends between [X/Fe] and distance (<0.02dex/kpc), but for some elements, there is a hint that the local (R_GC_<13kpc) and distant (R_GC_>13kpc) samples may have different trends with distance. There is no evidence for significant abundance trends versus age (<0.04dex/Gyr). We measure the linear relation between [X/Fe] and metallicity, [Fe/H], and find that the scatter about the mean trend is comparable to the measurement uncertainties. Comparison with solar neighborhood field giants shows that the open clusters share similar abundance ratios [X/Fe] at a given metallicity. While the flattening of the metallicity gradient and enhanced [{alpha}/Fe] ratios in the outer disk suggest a chemical enrichment history different from that of the solar neighborhood, we echo the sentiments expressed by Friel et al. that definitive conclusions await homogeneous analyses of larger samples of stars in larger numbers of clusters. Arguably, our understanding of the evolution of the outer disk from open clusters is currently limited by systematic abundance differences between various studies.
- ID:
- ivo://CDS.VizieR/J/ApJ/705/328
- Title:
- Abundance measurements in Sculptor dSph
- Short Name:
- J/ApJ/705/328
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of Fe, Mg, Si, Ca, and Ti abundances for 388 radial velocity member stars in the Sculptor dwarf spheroidal galaxy (dSph), a satellite of the Milky Way (MW). This is the largest sample of individual {alpha} element (Mg, Si, Ca, and Ti) abundance measurements in any single dSph. The measurements are made from Keck/Deep Imaging Multi-Object Spectrometer medium-resolution spectra (6400-9000{AA}, R~6500). Based on comparisons to published high-resolution (R>~20000) spectroscopic measurements, our measurements have uncertainties of {alpha}[Fe/H]=0.14 and {alpha}[{alpha}/Fe]=0.13. We have discovered one star with [Fe/H]=-3.80+/-0.28, which is the most metal-poor star known anywhere except the MW halo, but high-resolution spectroscopy is needed to measure this star's detailed abundances.
- ID:
- ivo://CDS.VizieR/J/ApJ/754/91
- Title:
- Abundances and velocities of NGC 6397 stars
- Short Name:
- J/ApJ/754/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used three sets of high-resolution spectra acquired with the multifiber facility FLAMES at the Very Large Telescope of the European Southern Observatory to investigate the chemical and kinematical properties of a sample of 42 horizontal branch (HB) stars, 18 blue straggler stars (BSSs), and 86 main-sequence (MS) turnoff (TO) and sub-giant branch stars in the nearby globular cluster NGC 6397. We measured rotational velocities and Fe, O, and Mg abundances. All of the unevolved stars in our sample have low rotational velocites (vsin i<10km/s), while the HB stars and BSSs show a broad distribution, with values ranging from 0 to ~70km/s. For HB stars with T<10500K there is a clear temperature-oxygen anticorrelation that can be understood if the star position along the HB is mainly determined by the He content. The hottest BSSs and HB stars (with temperatures T>8200K and T>10500K, respectively) also show significant deviations in their iron abundance with respect to the cluster metallicity (as traced by the unevolved stars, [Fe/H]=-2.12). While similar chemical patterns have already been observed in other hot HB stars, this is the first evidence ever collected for BSSs. We interpret these abundance anomalies as due to the metal radiative levitation, occurring in stars with shallow or no convective envelopes.
- ID:
- ivo://CDS.VizieR/J/ApJ/865/68
- Title:
- Abundances for 79 Sun-like stars within 100pc
- Short Name:
- J/ApJ/865/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The compositions of stars are a critical diagnostic tool for many topics in astronomy such as the evolution of our Galaxy, the formation of planets, and the uniqueness of the Sun. Previous spectroscopic measurements indicate a large intrinsic variation in the elemental abundance patterns of stars with similar overall metal content. However, systematic errors arising from inaccuracies in stellar models are known to be a limiting factor in such studies, and thus it is uncertain to what extent the observed diversity of stellar abundance patterns is real. Here we report the abundances of 30 elements with precisions of 2% for 79 Sun-like stars within 100pc. Systematic errors are minimized in this study by focusing on solar twin stars and performing a line-by-line differential analysis using high-resolution, high-signal-to-noise spectra. We resolve [X/Fe] abundance trends in galactic chemical evolution at precisions of 10^-3^dex/Gyr and reveal that stars with similar ages and metallicities have nearly identical abundance patterns. Contrary to previous results, we find that the ratios of carbon-to-oxygen and magnesium-to-silicon in solar-metallicity stars are homogeneous to within 10% throughout the solar neighborhood, implying that exoplanets may exhibit much less compositional diversity than previously thought. Finally, we demonstrate that the Sun has a subtle deficiency in refractory material relative to >80% of solar twins (at 2{sigma} confidence), suggesting a possible signpost for planetary systems like our own.
- ID:
- ivo://CDS.VizieR/J/ApJ/511/639
- Title:
- Abundances in blue compact galaxies
- Short Name:
- J/ApJ/511/639
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-quality ground-based spectroscopic observations of 54 supergiant H II regions in 50 low-metallicity blue compact galaxies with oxygen abundances 12+Log[O/H] between 7.1 and 8.3. We use the data to determine abundances for the elements N, O, Ne, S, Ar, and Fe. We also analyze Hubble Space Telescope (HST) Faint Object Spectrograph archival spectra of 10 supergiant H II regions to derive C and Si abundances in a subsample of seven blue compact galaxies. The main result of the present study is that none of the heavy element-to-oxygen abundance ratios studied here (C/O, N/O, Ne/O, Si/O, S/O, Ar/O, Fe/O) depend on oxygen abundance for blue compact galaxies with 12+Log[O/H]{<=}7.6 (Z{<=}Z_{solar}/20).
- ID:
- ivo://CDS.VizieR/J/ApJ/857/2
- Title:
- Abundances in 6 metal-poor stars
- Short Name:
- J/ApJ/857/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new abundances derived from CuI, CuII, ZnI, and ZnII lines in six warm (5766<=T_eff_<=6427K), metal-poor (-2.50<=[Fe/H]<=-0.95) dwarf and subgiant (3.64<=logg<=4.44) stars. These abundances are derived from archival high-resolution ultraviolet spectra from the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope and ground-based optical spectra from several observatories. Ionized Cu and Zn are the majority species, and abundances derived from CuII and ZnII lines should be largely insensitive to departures from local thermodynamic equilibrium (LTE). We find good agreement between the [Zn/H] ratios derived separately from ZnI and ZnII lines, suggesting that departures from LTE are, at most, minimal (<~0.1dex). We find that the [Cu/H] ratios derived from CuII lines are 0.36+/-0.06dex larger than those derived from CuI lines in the most metal-poor stars ([Fe/H]{<}-1.8), suggesting that LTE underestimates the Cu abundance derived from CuI lines. The deviations decrease in more metal-rich stars. Our results validate previous theoretical non-LTE calculations for both Cu and Zn, supporting earlier conclusions that the enhancement of [Zn/Fe] in metal-poor stars is legitimate, and the deficiency of [Cu/Fe] in metal-poor stars may not be as large as previously thought.
- ID:
- ivo://CDS.VizieR/J/ApJ/682/1217
- Title:
- Abundances in red giants in 7 globular clusters
- Short Name:
- J/ApJ/682/1217
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a technique that applies spectral synthesis to medium-resolution spectroscopy (MRS; R~6000) in the red (6300{AA}<{lambda}<9100{AA}) to measure [Fe/H] and [{alpha}/Fe] of individual red giant stars over a wide metallicity range. We apply our technique to 264 red giant stars in seven Galactic globular clusters and demonstrate that it reproduces the metallicities and {alpha}-enhancements derived from high-resolution spectroscopy (HRS). The MRS technique excludes the three CaII triplet lines and instead relies on a plethora of weaker lines. Unlike empirical metallicity estimators, such as the equivalent width of the CaII triplet, the synthetic method presented here is applicable over an arbitrarily wide metallicity range and is independent of assumptions about the {alpha}-enhancement.
- ID:
- ivo://CDS.VizieR/J/ApJS/191/352
- Title:
- Abundances in stars of Milky Way dwarf satellites
- Short Name:
- J/ApJS/191/352
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of Fe, Mg, Si, Ca, and Ti abundances for 2961 stars in eight dwarf satellite galaxies of the Milky Way (MW): Sculptor, Fornax, Leo I, Sextans, Leo II, Canes Venatici I, Ursa Minor, and Draco. For the purposes of validating our measurements, we also observed 445 red giants in MW globular clusters and 21 field red giants in the MW halo. The measurements are based on Keck/DEIMOS medium-resolution spectroscopy (MRS) combined with spectral synthesis. We estimate uncertainties in [Fe/H] by quantifying the dispersion of [Fe/H] measurements in a sample of stars in monometallic globular clusters (GCs). We estimate uncertainties in Mg, Si, Ca, and Ti abundances by comparing to high-resolution spectroscopic abundances of the same stars. For this purpose, a sample of 132 stars with published high-resolution spectroscopy in GCs, the MW halo field, and dwarf galaxies has been observed with MRS. The standard deviations of the differences in [Fe/H] and <[{alpha}/Fe]> (the average of [Mg/Fe], [Si/Fe], [Ca/Fe], and [Ti/Fe]) between the two samples is 0.15 and 0.16, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/870/83
- Title:
- Abundances in the ultra-faint dwarf gal. GruI & TriII
- Short Name:
- J/ApJ/870/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution spectroscopy of four stars in two candidate ultra-faint dwarf galaxies (UFDs), GrusI (GruI) and TriangulumII (TriII). Neither object currently has a clearly determined velocity dispersion, placing them in an ambiguous region of parameter space between dwarf galaxies and globular clusters (GCs). No significant metallicity difference is found for the two GruI stars, but both stars are deficient in neutron-capture elements. We verify previous results that TriII displays significant spreads in metallicity and [{alpha}/Fe]. Neutron-capture elements are not detected in our TriII data, but we place upper limits at the lower envelope of Galactic halo stars, consistent with previous very low detections. Stars with similarly low neutron-capture element abundances are common in UFDs but rare in other environments. This signature of low neutron-capture element abundances traces chemical enrichment in the least massive star-forming dark matter halos and further shows that the dominant sources of neutron-capture elements in metal-poor stars are rare. In contrast, all known GCs have similar ratios of neutron-capture elements to those of halo stars, suggesting that GCs do not form at the centers of their own dark matter halos. The low neutron-capture element abundances may be the strongest evidence that GruI and TriII are (or once were) galaxies rather than GCs, and we expect future observations of these systems to robustly find nonzero velocity dispersions or signs of tidal disruption. However, the nucleosynthetic origin of this low neutron-capture element floor remains unknown.
- 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/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/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/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/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/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/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/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/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/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/AJ/157/154
- Title:
- Abundances of RGs in Galactic globular clusters
- Short Name:
- J/AJ/157/154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Among stars in Galactic globular clusters the carbon abundance tends to decrease with increasing luminosity on the upper red giant branch, particularly within the lowest metallicity clusters. While such a phenomena is not predicted by canonical models of stellar interiors and evolution, it is widely held to be the result of some extra mixing operating during red giant branch ascent which transports material exposed to the CN(O)-cycle across the radiative zone in the stellar interior and into the base of the convective envelope, whereupon it is brought rapidly to the stellar surface. Here we present measurements of [C/Fe] abundances among 67 red giants in 19 globular clusters within the Milky Way. Building on the work of Martell et al. (2008AJ....136.2522M), we have concentrated on giants with absolute magnitudes of M_V_~-1.5 within clusters encompassing a range of metallicity (-2.4<[Fe/H]<-0.3). The Kitt Peak National Observatory (KPNO) 4 m and Southern Astrophysical Research (SOAR) 4.1 m telescopes were used to obtain spectra covering the {lambda}4300 CH and {lambda}3883 CN bands. The CH absorption features in these spectra have been analyzed via synthetic spectra in order to obtain [C/Fe] abundances. These abundances and the luminosities of the observed stars were used to infer the rate at which C abundances change with time during upper red giant branch evolution (i.e., the mixing efficiency). By establishing rates over a range of metallicity, the dependence of deep mixing on metallicity is explored. We find that the inferred carbon depletion rate decreases as a function of metallicity, although our results are dependent on the initial [C/Fe] composition assumed for each star.
- ID:
- ivo://CDS.VizieR/J/AZh/84/997
- Title:
- Abundances of Sr, Y, Zr, Ce and Ba
- Short Name:
- J/AZh/84/997
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Sr, Y, Zr, and Ce abundances are derived for the sample of 74 cool dwarfs and subgiants with the iron abundance [Fe/H] ranged between -2.43 and 0.25. The results are based on LTE (Y, Zr and Ce) and non-LTE (Sr) line formation and line profile analysis of high resolution (40000 and 60000) spectra that have a typical S/N of 50-200. The Zr/Y, Sr/Y, and Sr/Zr ratios in the halo stars form nearly a plateau over the wide metallicity range, -2.43<=[Fe/H]<=0.90, indicating a common origin of Sr, Y, and Zr at the epoch of the halo formation. We find a steep decline of [Zr/Y] in the thick disk stars with increasing Ba abundance. This suggests the reduction of the production rate of Zr compared to that for Y at the active phase of the thick disk formation. The halo and thick disk stars reveal an overabundance of Zr relative to barium that grows with decreasing Ba abundance. There is a clear correlation of the [Zr/Ba] and [Eu/Ba] abundance ratios. Our observational findings for the halo and thick disk do not support the Galaxy chemical evolution models available in the literature and require to improve their predictions. The thin disk stars reveal, on average, solar abundance ratios for (Y,Zr)/Fe, (Y,Zr)/Ba, and Zr/Y. We note a slight decline of Zr/Ba and Zr/Y in these stars with increasing Ba abundance. Our results favour a dominance of the asymptotic giant branch stars in the heavy element enrichment of the interstellar gas over the epoch of the thin disk existence, in agreement with the theory of the main s-process nucleosynthesis.
- ID:
- ivo://CDS.VizieR/J/ApJ/889/27
- Title:
- Abundances of 11 stars in Carina II and III
- Short Name:
- J/ApJ/889/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first detailed elemental abundances in the ultra-faint Magellanic satellite galaxies Carina II (Car II) and Carina III (CarIII). With high-resolution Magellan/MIKE spectroscopy, we determined the abundances of nine stars in Car II, including the first abundances of an RR Lyrae star in an ultra-faint dwarf galaxy (UFD), and two stars in Car III. The chemical abundances demonstrate that both systems are clearly galaxies and not globular clusters. The stars in these galaxies mostly display abundance trends matching those of other similarly faint dwarf galaxies: enhanced but declining [{alpha}/Fe] ratios, iron-peak elements matching the stellar halo, and unusually low neutron-capture element abundances. One star displays a low outlying [Sc/Fe]=-1.0. We detect a large Ba scatter in Car II, likely due to inhomogeneous enrichment by low-mass asymptotic giant branch star winds. The most striking abundance trend is for [Mg/Ca] in Car II, which decreases from +0.4 to -0.4 and indicates clear variation in the initial progenitor masses of enriching core-collapse supernovae. So far, the only UFDs displaying a similar [Mg/Ca] trend are likely satellites of the Large Magellanic Cloud. We find two stars with [Fe/H]<=-3.5 whose abundances likely trace the first generation of metal-free Population III stars and are well fit by Population III core-collapse supernova yields. An appendix describes our new abundance uncertainty analysis that propagates line-by-line stellar parameter uncertainties.
- ID:
- ivo://CDS.VizieR/J/ApJ/854/184
- Title:
- Abundances of stars in 3 open clusters
- Short Name:
- J/ApJ/854/184
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Single stars in open clusters with known distances are important targets in constraining the nucleosynthesis process since their ages and luminosities are also known. In this work, we analyze a sample of 29 single red giants of the open clusters NGC2360, NGC3680, and NGC5822 using high-resolution spectroscopy. We obtained atmospheric parameters, abundances of the elements C, N, O, Na, Mg, Al, Ca, Si, Ti, Ni, Cr, Y, Zr, La, Ce, and Nd, as well as radial and rotational velocities. We employed the local thermodynamic equilibrium atmospheric models of Kurucz and the spectral analysis code moog. Rotational velocities and light-element abundances were derived using spectral synthesis. Based on our analysis of the single red giants in these three open clusters, we could compare, for the first time, their abundance pattern with that of the binary stars of the same clusters previously studied. Our results show that the abundances of both single and binary stars of the open clusters NGC 2360, NGC 3680, and NGC 5822 do not have significant differences. For the elements created by the s-process, we observed that the open clusters NGC2360, NGC3680, and NGC5822 also follow the trend already raised in the literature that young clusters have higher s-process element abundances than older clusters. Finally, we observed that the three clusters of our sample exhibit a trend in the [Y/Mg]-age relation, which may indicate the ability of the [Y/Mg] ratio to be used as a clock for the giants.
- ID:
- ivo://CDS.VizieR/J/ApJ/855/83
- Title:
- Abundances of very metal-poor stars in Sagittarius
- Short Name:
- J/ApJ/855/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Sagittarius (Sgr) is a massive disrupted dwarf spheroidal galaxy in the Milky Way halo that has undergone several stripping events. Previous chemical studies were restricted mainly to a few, metal-rich ([Fe/H]>~-1) stars that suggested a top-light initial mass function (IMF). Here we present the first high-resolution, very metal-poor ([Fe/H]=-1 to -3) sample of 13 giant stars in the main body of Sgr. We derive abundances of 13 elements, namely C, Ca, Co, Fe, Sr, Ba, La, Ce, Nd, Eu, Dy, Pb, and Th, that challenge the interpretation based on previous studies. Our abundances from Sgr mimic those of the metal-poor halo, and our most metal-poor star ([Fe/H]~-3) indicates a pure r-process pollution. Abundances of Sr, Pb, and Th are presented for the first time in Sgr, allowing for age determination using nuclear cosmochronology. We calculate ages of 9+/-2.5Gyr. Most of the sample stars have been enriched by a range of asymptotic giant branch (AGB) stars with masses between 1.3 and 5M_{sun}_. SgrJ190651.47-320147.23 shows a large overabundance of Pb (2.05dex) and a peculiar abundance pattern best fit by a 3M_{sun}_ AGB star. Based on star-to-star scatter and observed abundance patterns, a mixture of low- and high-mass AGB stars and supernovae (15-25M_{sun}_) is necessary to explain these patterns. The high level (0.29+/-0.05dex) of Ca indicates that massive supernovae must have existed and polluted the early ISM of Sgr before it lost its gas. This result is in contrast with a top-light IMF with no massive stars polluting Sgr.
- ID:
- ivo://CDS.VizieR/J/ApJ/723/1632
- Title:
- Abundance spreads in Bootes I and Segue 1
- Short Name:
- J/ApJ/723/1632
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an AAOmega spectroscopic study of red giants in the ultra-faint dwarf galaxy Bootes I (M_V_~-6) and the Segue 1 system (M_V_~-1.5), either an extremely low luminosity dwarf galaxy or an unusually extended globular cluster. Both Bootes I and Segue 1 have significant abundance dispersions in iron and carbon. Bootes I has a mean abundance of [Fe/H]=-2.55+/-0.11 with an [Fe/H] dispersion of {sigma}=0.37+/-0.08, and abundance spreads of {Delta}[Fe/H]=1.7 and {Delta}[C/H]=1.5. Segue 1 has a mean of [Fe/H]=-2.7+/-0.4 with [Fe/H] dispersion of {sigma}=0.7+/-0.3, and abundances spreads of {Delta}[Fe/H]=1.6 and {Delta}[C/H]=1.2. Moreover, Segue 1 has a radial-velocity member at four half-light radii that is extremely metal-poor and carbon-rich, with [Fe/H]=-3.5, and [C/Fe]=+2.3. Modulo an unlikely non-member contamination, the [Fe/H] abundance dispersion confirms Segue 1 as the least-luminous ultra-faint dwarf galaxy known.
- ID:
- ivo://CDS.VizieR/J/A+A/538/A100
- Title:
- Abundances red giants in Carina dSph
- Short Name:
- J/A+A/538/A100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ages of individual Red Giant Branch stars can range from 1Gyr old to the age of the Universe, and it is believed that the abundances of most chemical elements in their photospheres remain unchanged with time (those that are not affected by the first dredge-up). This means that they trace the interstellar medium in the galaxy at the time the star formed, and hence the chemical enrichment history of the galaxy. Colour-Magnitude Diagram analysis has shown the Carina dwarf spheroidal to have had an unusually episodic star formation history and this is expected to be reflected in the abundances of different chemical elements.
- ID:
- ivo://CDS.VizieR/J/ApJ/848/68
- Title:
- Abundances & RVs of stable and Blazhko RRc stars
- Short Name:
- J/ApJ/848/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyzed series of spectra obtained for 12 stable RRc stars observed with the echelle spectrograph of the du Pont telescope at Las Campanas Observatory and we analyzed the spectra of RRc Blazhko stars discussed by Govea+ (2014, J/ApJ/782/59). We derived model atmosphere parameters, [Fe/H] metallicities, and [X/Fe] abundance ratios for 12 species of 9 elements. We co-added all spectra obtained during the pulsation cycles to increase signal to noise and demonstrate that these spectra give results superior to those obtained by co-addition in small phase intervals. The RRc abundances are in good agreement with those derived for the RRab stars of Chadid+ (2017ApJ...835..187C). We used radial velocity (RV) measurements of metal lines and H{alpha} to construct variations of velocity with phase, and center-of-mass velocities. We used these to construct RV templates for use in low- to medium-resolution RV surveys of RRc stars. Additionally, we calculated primary accelerations, radius variations, and metal and H{alpha} velocity amplitudes, which we display as regressions against primary acceleration. We employ these results to compare the atmosphere structures of metal-poor RRc stars with their RRab counterparts. Finally, we use the RV data for our Blazhko stars and the Blazhko periods of Szczygiel & Fabrycky (2007, J/MNRAS/377/1263) to falsify the Blazhko oblique rotator hypothesis.
- ID:
- ivo://CDS.VizieR/J/AJ/155/180
- Title:
- A catalog of cool dwarf targets for the TESS
- Short Name:
- J/AJ/155/180
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of cool dwarf targets (V-J>2.7, T_eff_~<4000 K) and their stellar properties for the upcoming Transiting Exoplanet Survey Satellite (TESS), for the purpose of determining which cool dwarfs should be observed using two minute observations. TESS has the opportunity to search tens of thousands of nearby, cool, late K- and M-type dwarfs for transiting exoplanets, an order of magnitude more than current or previous transiting exoplanet surveys, such as Kepler, K2, and ground-based programs. This necessitates a new approach to choosing cool dwarf targets. Cool dwarfs are chosen by collating parallax and proper motion catalogs from the literature and subjecting them to a variety of selection criteria. We calculate stellar parameters and TESS magnitudes using the best possible relations from the literature while maintaining uniformity of methods for the sake of reproducibility. We estimate the expected planet yield from TESS observations using statistical results from the Kepler mission, and use these results to choose the best targets for two minute observations, optimizing for small planets for which masses can conceivably be measured using follow-up Doppler spectroscopy by current and future Doppler spectrometers. The catalog is available in machine readable format and is incorporated into the TESS Input Catalog and TESS Candidate Target List until a more complete and accurate cool dwarf catalog identified by ESA's Gaia mission can be incorporated.
- ID:
- ivo://CDS.VizieR/J/A+A/445/765
- Title:
- A Catalog of Edge-on Disk Galaxies
- Short Name:
- J/A+A/445/765
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spiral galaxies range from bulge-dominated early-type galaxies to late types with little or no bulge. Cosmological models do not predict the formation of disk-dominated, essentially bulgeless galaxies, yet these objects exist. A particularly striking and poorly understood example of bulgeless galaxies are flat or superthin galaxies with large axis ratios. We therefore embarked on a study aimed at a better understanding of these enigmatic objects, starting by compiling a statistically meaningful sample with well-defined properties. The disk axis ratios can be most easily measured when galaxies are seen edge-on. We used data from the Sloan Digital Sky Survey (SDSS) in order to identify edge-on galaxies with disks in a uniform, reproducible, automated fashion. In the five-color photometric database of the SDSS Data Release 1 (DR1, http://www.sdss.org/dr1) (2099 deg^2) we identified 3169 edge-on disk galaxies, which we subdivided into disk galaxies with bulge, intermediate types, and simple disk galaxies without any obvious bulge component. We subdivided these types further into subclasses: Sa(f), Sb(f), Sc(f), Scd(f), Sd(f), Irr(f), where the (f) indicates that these galaxies are seen edge-on. Here we present our selection algorithm and the resulting catalogs of the 3169 edge-on disk galaxies including the photometric, morphological, and structural parameters of our targets. A number of incompleteness effects affect our catalog, but it contains almost a factor of four more bulgeless galaxies with prominent simple disks (flat galaxies) within the area covered here than optical previous catalogs, which were based on the visual selection from photographic plates (Karachentsev et al. 1999, see Cat. VII/219). We find that approximately 15% of the edge-on disk galaxies in our catalog are flat galaxies, demonstrating that these galaxies are fairly common, especially among intermediate- mass star-forming galaxies. Bulgeless disks account for roughly one third of our galaxies when also puffy disks and edge-on irregulars are included. Our catalog provides a uniform database for a multitude of follow-up studies of bulgeless galaxies in order to constrain their intrinsic and environmental properties and their evolutionary status.
- ID:
- ivo://CDS.VizieR/J/ApJS/245/10
- Title:
- A catalog of galaxies in direction of Perseus
- Short Name:
- J/ApJS/245/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 5437 morphologically classified sources in the direction of the Perseus galaxy cluster core, among them 496 early-type low-mass galaxy candidates. The catalog is primarily based on V-band imaging data acquired with the William Herschel Telescope, which we used to conduct automated source detection and derive photometry. We additionally reduced archival Subaru multiband imaging data in order to measure aperture colors and perform a morphological classification, benefiting from 0.5" seeing conditions in the r-band data. Based on morphological and color properties, we extracted a sample of early-type low-mass galaxy candidates with absolute V-band magnitudes in the range of -10 to -20mag. In the color-magnitude diagram, the galaxies are located where the red sequence for early-type cluster galaxies is expected, and they lie on the literature relation between absolute magnitude and Sersic index. We classified the early-type dwarf candidates into nucleated and nonnucleated galaxies. For the faint candidates, we found a trend of increasing nucleation fraction toward brighter luminosity or higher surface brightness, similar to what is observed in other nearby galaxy clusters. We morphologically classified the remaining sources as likely background elliptical galaxies, late-type galaxies, edge-on disk galaxies, and likely merging systems and discussed the expected contamination fraction through non-early-type cluster galaxies in the magnitude-size surface brightness parameter space. Our catalog reaches its 50% completeness limit at an absolute V-band luminosity of -12mag and a V-band surface brightness of 26mag/arcsec^2^. This makes it the largest and deepest catalog with coherent coverage compared to previous imaging studies of the Perseus cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/160/271
- Title:
- A catalog of ~30000 galaxies with ALFALFA-SDSS
- Short Name:
- J/AJ/160/271
- Date:
- 08 Dec 2021
- Publisher:
- CDS
- Description:
- We present a HI optical catalog of ~30000 galaxies based on the 100% complete Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) survey combined with data from the Sloan Digital Sky Survey (SDSS). Our goal is to facilitate the public use of the completed ALFALFA catalog by providing carefully determined matches to SDSS counterparts, including matches for ~10000 galaxies that do not have SDSS spectra. These identifications can provide a basis for further crossmatching with other surveys using SDSS photometric IDs as a reference point. We derive absolute magnitudes and stellar masses for each galaxy using optical colors combined with an internal reddening correction designed for small- and intermediate-mass galaxies with active star formation. We also provide measures of stellar masses and star formation rates based on infrared and/or ultraviolet photometry for galaxies that are detected by the Wide-field Infrared Survey Explorer and/or the Galaxy Evolution Explorer. Finally, we compare the galaxy population in the ALFALFA-SDSS sample with the populations in several other publicly available galaxy catalogs and confirm that ALFALFA galaxies typically have lower masses and bluer colors.