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- ID:
- ivo://CDS.VizieR/J/AJ/150/88
- Title:
- Abundances in the local region. I. G and K giants
- Short Name:
- J/AJ/150/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Parameters and abundances for 1133 stars of spectral types F, G, and K of luminosity class III have been derived. In terms of stellar parameters, the primary point of interest is the disagreement between gravities derived with masses determined from isochrones, and gravities determined from an ionization balance. This is not a new result per se, but the size of this sample emphasizes the severity of the problem. A variety of arguments led to the selection of the ionization-balance gravity as the working value. The derived abundances indicate that the giants in the solar region have Sun-like total abundances and abundance ratios. Stellar evolution indicators have also been investigated with the Li abundances and the [C/Fe] and C/O ratios, indicating that standard processing has been operating in these stars. The more salient result for stellar evolution is that the [C/Fe] data across the red-giant clump indicates the presence of mass-dependent mixing in accord with standard stellar evolution predictions.
- ID:
- ivo://CDS.VizieR/J/AJ/153/21
- Title:
- Abundances in the local region. II. F, G, and K dwarfs
- Short Name:
- J/AJ/153/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Parameters and abundances have been derived for 1002 stars of spectral types F, G, and K, and luminosity classes IV and V. After culling the sample for rotational velocity and effective temperature, 867 stars remain for discussion. Twenty-eight elements are considered in the analysis. The {alpha}, iron-peak, and Period 5 transition metal abundances for these stars show a modest enhancement over solar averaging about 0.05dex. The lanthanides are more abundant, averaging about +0.2dex over solar. The question is: Are these stars enhanced, or is the Sun somewhat metal-poor relative to these stars? The consistency of the abundances derived here supports an argument for the latter view. Lithium, carbon, and oxygen abundances have been derived. The stars show the usual lithium astration as a function of mass/temperature. There are more than 100 planet-hosts in the sample, and there is no discernible difference in their lithium content, relative to the remaining stars. The carbon and oxygen abundances show the well-known trend of decreasing [x/Fe] ratio with increasing [Fe/H].
- ID:
- ivo://CDS.VizieR/J/AJ/155/111
- Title:
- Abundances in the local region. III. Southern dwarfs
- Short Name:
- J/AJ/155/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar parameters and abundances have been derived from a sample of 907 F, G, and K dwarfs. The high-resolution, high signal-to-noise spectra utilized were acquired with the HARPS spectrograph of the European Southern Observatory. The stars in the sample with -0.2<[Fe/H]<+0.2 have abundances that strongly resemble that of the Sun, except for the lithium content and the lanthanides. Near the solar temperature, stars show two orders of magnitude range in lithium content. The average content of stars in the local region appears to be enhanced at about the +0.1 level relative to the Sun for the lanthanides. There are over 100 planet hosts in this sample, and there is no discernible difference between them and the non-hosts regarding their lithium content.
- ID:
- ivo://CDS.VizieR/J/A+A/414/503
- Title:
- Abundances in the Sgr dSph
- Short Name:
- J/A+A/414/503
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on abundances of O, Mg, Si, Ca and Fe for 10 giants in the Sgr dwarf spheroidal derived from high resolution spectra obtained with UVES at the 8.2m Kueyen-VLT telescope. The iron abundance spans the range -0.8<~[Fe/H]<~0.0 and the dominant population is relatively metal-rich with [Fe/H]~-0.25.
- 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/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/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.
