- 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.
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- 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/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/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/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.
