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2741. [C/H] Chemical abundances of 1110 stars
ID:
ivo://CDS.VizieR/J/A+A/599/A96
Title:
[C/H] Chemical abundances of 1110 stars
Short Name:
J/A+A/599/A96
Date:
21 Oct 2021
Publisher:
CDS
Description:
Carbon, oxygen and nitrogen (CNO) are key elements in stellar formation and evolution, and their abundances should also have a significant impact on planetary formation and evolution. We aim to present a detailed spectroscopic analysis of 1110 solar-type stars, 143 of which are known to have planetary companions. We have determined the carbon abundances of these stars and investigate a possible connection between C and the presence of planetary companions. We used the HARPS spectrograph to obtain high-resolution optical spectra of our targets. Spectral synthesis of the CH band at 4300{AA} was performed with the spectral synthesis codes MOOG and FITTING. We have studied carbon in several reliable spectral windows and have obtained abundances and distributions that show that planet host stars are carbon rich when compared to single stars, a signature caused by the known metal-rich nature of stars with planets. We find no different behaviour when separating the stars by the mass of the planetary companion. We conclude that reliable carbon abundances can be derived for solar-type stars from the CH band at 4300{AA}. We confirm two different slope trends for [C/Fe] with [Fe/H] because the behaviour is opposite for stars above and below solar values. We observe a flat distribution of the [C/Fe] ratio for all planetary masses, a finding that apparently excludes any clear connection between the [C/Fe] abundance ratio and planetary mass.
2742. Chemical abundance analysis of 5 stars in Sculptor
ID:
ivo://CDS.VizieR/J/ApJ/802/93
Title:
Chemical abundance analysis of 5 stars in Sculptor
Short Name:
J/ApJ/802/93
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a homogeneous chemical abundance analysis of five of the most metal-poor stars in the Sculptor dwarf spheroidal galaxy. We analyze new and archival high resolution spectroscopy from Magellan/MIKE and VLT/UVES and determine stellar parameters and abundances in a consistent way for each star. Two of the stars in our sample, at [Fe/H]=-3.5 and [Fe/H]=-3.8, are new discoveries from our Ca K survey of Sculptor, while the other three were known in the literature. We confirm that Scl 07-50 is the lowest metallicity star identified in an external galaxy, at [Fe/H]=-4.1. The two most metal-poor stars both have very unusual abundance patterns, with striking deficiencies of the {alpha} elements, while the other three stars resemble typical extremely metal-poor Milky Way halo stars. We show that the star-to-star scatter for several elements in Sculptor is larger than that for halo stars in the same metallicity range. This scatter and the uncommon abundance patterns of the lowest metallicity stars indicate that the oldest surviving Sculptor stars were enriched by a small number of earlier supernovae, perhaps weighted toward high-mass progenitors from the first generation of stars the galaxy formed.
2743. Chemical abundance in 10 open clusters
ID:
ivo://CDS.VizieR/J/AJ/142/59
Title:
Chemical abundance in 10 open clusters
Short Name:
J/AJ/142/59
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a detailed chemical abundance study of evolved stars in 10 open clusters based on Hydra multi-object echelle spectra obtained with the WIYN 3.5m telescope. From an analysis of both equivalent widths and spectrum synthesis, abundances have been determined for the elements Fe, Na, O, Mg, Si, Ca, Ti, Ni, Zr, and for two of the 10 clusters, Al and Cr. To our knowledge, this is the first detailed abundance analysis for clusters NGC 1245, NGC 2194, NGC 2355, and NGC 2425.
2744. Chemical abundance of Hercules moving group
ID:
ivo://CDS.VizieR/J/AZh/88/284
Title:
Chemical abundance of Hercules moving group
Short Name:
J/AZh/88/284
Date:
21 Oct 2021
Publisher:
CDS
Description:
The results of a comparative analysis of the kinematics, ages, and elemental abundances for 17 red giants in the Hercules moving group are presented. Model atmospheres are used to determine the parameters of the stellar atmospheres and the abundances of about 20 elements. The masses and ages of the stars are estimated, and the components of their Galactic velocities and the elements of their Galactic orbits are calculated. Our analysis demonstrates that the Hercules stream is a heterogeneous group of objects from the thin and thick disks.
2745. Chemical abundance of 12 stars in open clusters
ID:
ivo://CDS.VizieR/J/A+A/535/A30
Title:
Chemical abundance of 12 stars in open clusters
Short Name:
J/A+A/535/A30
Date:
21 Oct 2021
Publisher:
CDS
Description:
Open clusters are ideal test particles for studying the chemical evolution of the Galactic disc. However, the number and accuracy of existing high-resolution abundance determinations, not only of [Fe/H], but also of other key elements, remains largely insufficient. We attempt to increase the number of Galactic open clusters that have high quality abundance determinations, and to gather all the literature determinations published so far.
2746. Chemical abundances for 83 transit hosts
ID:
ivo://CDS.VizieR/J/A+A/558/A106
Title:
Chemical abundances for 83 transit hosts
Short Name:
J/A+A/558/A106
Date:
21 Oct 2021
Publisher:
CDS
Description:
Precise stellar parameters are crucial in exoplanet research for correctly determining of the planetary parameters. For stars hosting a transiting planet, determining of the planetary mass and radius depends on the stellar mass and radius, which in turn depend on the atmospheric stellar parameters. Different methods can provide different results, which leads to different planet characteristics. In this paper, we use a uniform method to spectroscopically derive stellar atmospheric parameters, chemical abundances, stellar masses, and stellar radii for a sample of 90 transit hosts. Surface gravities are also derived photometrically using the stellar density as derived from the light curve. We study the effect of using these different surface gravities on the determination of the chemical abundances and the stellar mass and radius. A spectroscopic analysis based on Kurucz models in LTE was performed through the MOOG code to derive the atmospheric parameters and the chemical abundances. The photometric surface gravity was determined through isochrone fitting and the use of the stellar density, directly determined from the light curve. Stellar masses and radii are determined through calibration formulae. Spectroscopic and photometric surface gravities differ, but this has very little effect on the precise determination of the stellar mass in our spectroscopic analysis. The stellar radius, and hence the planetary radius, is most affected by the surface gravity discrepancies. For the chemical abundances, the difference is, as expected, only noticable for the abundances derived from analyzing of lines of ionized species.
2747. Chemical abundances in Galactic PNe
ID:
ivo://CDS.VizieR/J/A+A/567/A12
Title:
Chemical abundances in Galactic PNe
Short Name:
J/A+A/567/A12
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new low-resolution (R~800) optical spectra of 22 Galactic PNe with Spitzer spectra. These data are combined with recent optical spectroscopic data available in the literature to construct representative samples of compact (and presumably young) Galactic disc and bulge PNe with Spitzer spectra. Attending to the nature of the dust features seen in their Spitzer spectra, Galactic disc and bulge PNe are classified according to four major dust types (oxygen chemistry or OC, carbon chemistry or CC, double chemistry or DC, featureless or F) and subtypes (amorphous and crystalline, and aliphatic and aromatic). Nebular gas abundances of He, N, O, Ne, S, Cl, and Ar, as well as plasma parameters (e.g. Ne, Te) are homogeneously derived and we study the median chemical abundances and nebular properties in Galactic disc and bulge PNe depending on their Spitzer dust types and subtypes. A comparison of the derived median abundance patterns with AGB nucleosynthesis predictions show mainly that i) DC PNe, both with amorphous and crystalline silicates, display high-metallicity (solar/supra-solar) and the highest He abundances and N/O ratios, suggesting relatively massive (~3-5M_{sun}_) hot bottom burning AGB stars as progenitors; ii) PNe with O-rich and C-rich unevolved dust (amorphous and aliphatic) seem to evolve from subsolar metallicity (z~0.008) and lower mass (<3M_{sun}_) AGB stars; iii) a few O-rich PNe and a significant fraction of C-rich PNe with more evolved dust (crystalline and aromatic, respectively) display chemical abundances similar to DC PNe, suggesting that they are related objects. A comparison of the derived nebular properties with predictions from models combining the theoretical central star evolution with a simple nebular model is also presented. Finally, a possible link between the Spitzer dust properties, chemical abundances, and evolutionary status is discussed.
2748. Chemical Abundances in Late-Type Stars
ID:
ivo://CDS.VizieR/III/193
Title:
Chemical Abundances in Late-Type Stars
Short Name:
III/193
Date:
21 Oct 2021
Publisher:
CDS
Description:
The catalogue includes chemical abundances determinations (from Li to Eu) and atmospheric parameters (Teff, logg, microturbulent velocity) obtained from re-analyses of 1108 Late-Type Stars. It contains field stars of the Galaxy, of open and globular cluster stars, and stars belonging to the LMC and the SMC. Almost all of these stars are referenced in the Cayrel de Strobel et al.'s [Fe/H] catalog (see cat. <III/200>). Most of the abundance results are very reliable within 0.2dex when using different sources of equivalent widths taken from the literature for a given star.
2749. Chemical abundances in Leo I and II dSph
ID:
ivo://CDS.VizieR/J/MNRAS/378/318
Title:
Chemical abundances in Leo I and II dSph
Short Name:
J/MNRAS/378/318
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have obtained calcium abundances and radial velocities for 102 red giant branch (RGB) stars in the Leo I dwarf spheroidal galaxy (dSph) and 74 RGB stars in the Leo II dSph using the low-resolution spectrograph (LRIS) on the Keck I 10-m telescope. We report on the calcium abundances [Ca/H] derived from the strengths of the Ca ii triplet absorption lines at 8498, 8542 and 8662{AA} in the stellar spectra using a new empirical Ca II triplet calibration to [Ca/H].
2750. Chemical abundances in 43 metal-poor stars
ID:
ivo://CDS.VizieR/J/A+A/440/321
Title:
Chemical abundances in 43 metal-poor stars
Short Name:
J/A+A/440/321
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have derived abundances of O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Fe, Ni and Ba for 43 metal-poor field stars in the solar neighbourhood, most of them subgiants or turn-off-point stars, with iron abundances [Fe/H] ranging from -0.4 to -3.0. About half of this sample has not been analysed spectroscopically in detail before. Effective temperatures were estimated from uvby photometry, and surface gravities primarily from Hipparcos parallaxes. The analysis is differential relative to the Sun, and carried out with plane-parallel MARCS models. Various sources of error are discussed and found to contribute a total error of about 0.1-0.2dex for most elements, while relative abundances, such as [Ca/Fe], are most probably more accurate. For the oxygen abundances, determined in an NLTE analysis of the 7774{AA} triplet lines, the errors may be somewhat larger.

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