Search

Start Over Validation Level 2
351. Abundances of 94 stars
ID:
ivo://CDS.VizieR/J/A+A/530/A15
Title:
Abundances of 94 stars
Short Name:
J/A+A/530/A15
Date:
21 Oct 2021
Publisher:
CDS
Description:
Abundances of Mn, Cu, Zn, Y, and Ba are determined for a sample of stars previously studied by Nissen & Schuster (2010, Cat. J/A+A/511/L10). Equivalent widths of atomic lines are measured from high resolution VLT/UVES and NOT/FIES spectra and used to derive abundance ratios from an LTE analysis based on MARCS model atmospheres. The analysis is made relative to two thick-disk stars, HD22879 and HD76932, such that very precise differential values are obtained.
352. Abundances of stars hosting planets
ID:
ivo://CDS.VizieR/J/ApJ/720/1290
Title:
Abundances of stars hosting planets
Short Name:
J/ApJ/720/1290
Date:
21 Oct 2021
Publisher:
CDS
Description:
The metal content of planet-hosting stars is an important ingredient that may affect the formation and evolution of planetary systems. Accurate stellar abundances require the determinations of reliable physical parameters, namely, the effective temperature, surface gravity, microturbulent velocity, and metallicity. This work presents the homogeneous derivation of such parameters for a large sample of stars hosting planets (N=117), as well as a control sample of disk stars not known to harbor giant, closely orbiting planets (N=145). Stellar parameters and iron abundances are derived from an automated analysis technique developed for this work. As previously found in the literature, the results in this study indicate that the metallicity distribution of planet-hosting stars is more metal rich by ~0.15 dex when compared to the control sample stars. A segregation of the sample according to planet mass indicates that the metallicity distribution of stars hosting only Neptunian-mass planets (with no Jovian-mass planets) tends to be more metal poor in comparison with that obtained for stars hosting a closely orbiting Jovian planet. The significance of this difference in metallicity arises from a homogeneous analysis of samples of FGK dwarfs which do not include the cooler and more problematic M dwarfs.
353. Abundances of 11 stars in Carina II and III
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.
354. Abundances of stars in lower main sequence
ID:
ivo://CDS.VizieR/J/A+A/489/923
Title:
Abundances of stars in lower main sequence
Short Name:
J/A+A/489/923
Date:
21 Oct 2021
Publisher:
CDS
Description:
The aim of this paper is to provide fundamental parameters and abundances with a high accuracy for a large sample of cool main sequence stars. This study is part of wider project, in which the metallicity distribution of the local thin disc is investigated from a complete sample of G and K dwarfs within 25pc. The stars were observed at high resolution and a high signal-to-noise ratio with the ELODIE echelle spectrograph. The Vsini were obtained with a calibration of the cross-correlation function. Effective temperatures were estimated by the line depth ratio method. Surface gravities (logg) were determined by two methods: parallaxes and ionization balance of iron. The Mg and Na abundances were derived using a non-LTE approximation. Abundances of other elements were obtained by measuring equivalent widths. Rotational velocities, atmospheric parameters Teff, logg, [Fe/H], Vt, and Li, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Co, Ni, and Zn abundances are provided for 131 stars. Among them, more than 30 stars are active stars with a fraction of BY Dra and RS CVn type stars for which spectral peculiarities were investigated. We find the mean abundances of the majority of elements in active and non-active stars to be similar, except for Li, and possibly for Zn and Co. The lithium is reliably detected in 54% of active stars but only in 20% of non -active stars. No correlation is found between Li abundances and rotational velocities. A possible anticorrelation of log A(Li) with the index of chromospheric activity GrandS is observed. Active and non active cool dwarfs show similar dependencies of most elemental ratios vs [Fe/H]. This allows us to use such abundance ratios to study the chemical and dynamical evolution of the Galaxy. Among active stars, no clear correlation has been found between different indicators of activity for our sample stars.
355. Abundances of stars in M3 and M13
ID:
ivo://CDS.VizieR/J/AJ/129/303
Title:
Abundances of stars in M3 and M13
Short Name:
J/AJ/129/303
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have carried out a detailed abundance analysis for 21 elements in a sample of 27 stars with a wide range in luminosity from luminous giants to stars near the main-sequence turnoff in the globular cluster M13 ([Fe/H]=-1.50dex) and in a sample of 13 stars distributed from the tip to the base of the red giant branch (RGB) in the globular cluster M3 ([Fe/H]=-1.39dex). The analyzed spectra, obtained with HIRES at the Keck Observatory, are of high dispersion (R={lambda}/{Delta}{lambda}=35000).
356. Abundances of stars in 3 open clusters
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.
357. Abundances of 8 stars in the Draco dSph
ID:
ivo://CDS.VizieR/J/ApJ/701/1053
Title:
Abundances of 8 stars in the Draco dSph
Short Name:
J/ApJ/701/1053
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an abundance analysis based on high-resolution spectra of eight stars selected to span the full range in metallicity in the Draco dwarf spheroidal (dSph) galaxy. We find that [Fe/H] for the sample stars ranges from -1.5 to -3.0dex. Combining our sample with previously published work for a total of 14 luminous Draco giants, we show that the abundance ratios [Na/Fe], [Mg/Fe], and [Si/Fe] for the Draco giants overlap those of Galactic halo giants at the lowest [Fe/H] probed, but are significantly lower for the higher Fe-metallicity Draco stars. Using a toy model we compare the behavior of the abundance ratios within the sample of Draco giants with those from the literature of Galactic globular clusters, and the Carina and Sgr dSph galaxies.
358. Abundances of stars in 47 Tuc
ID:
ivo://CDS.VizieR/J/AJ/135/1551
Title:
Abundances of stars in 47 Tuc
Short Name:
J/AJ/135/1551
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present chemical abundances for O, Na, Mg, Al, Si, Ca, Ti, and Fe in eight red giants and one turnoff star in the metal-rich globular cluster 47 Tuc, based on spectroscopy with the Magellan Inamori Kyocera Echelle high-resolution spectrograph on the Magellan 6.5m Clay telescope. A robust line by a line differential abundance analysis technique, relative to the K-giant Arcturus, was used to reduce systematic errors from atmospheric and atomic parameters.
359. Abundances of stars within 15pc of the Sun
ID:
ivo://CDS.VizieR/J/AJ/129/1063
Title:
Abundances of stars within 15pc of the Sun
Short Name:
J/AJ/129/1063
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an abundance analysis for stars within 15pc of the Sun located north of -30{deg} declination. We have limited our abundance sample to absolute magnitudes brighter than +7.5 and have eliminated several A stars in the local vicinity. Our final analysis list numbers 114 stars. Unlike Allende Prieto et al. (2004, Cat. <J/A+A/420/183>) in their consideration of a very similar sample, we have enforced strict spectroscopic criteria in the determination of atmospheric parameters. Nevertheless, our results are very similar to theirs. We determine the mean metallicity of the local region to be <[Fe/H]>=-0.07 using all stars and -0.04 when interlopers from the thick disk are eliminated.
360. Abundances of stars with planets
ID:
ivo://CDS.VizieR/J/ApJ/732/55
Title:
Abundances of stars with planets
Short Name:
J/ApJ/732/55
Date:
21 Oct 2021
Publisher:
CDS
Description:
Precise abundances of 18 elements have been derived for 10 stars known to host giant planets from high signal-to-noise ratio, high-resolution echelle spectroscopy. Internal uncertainties in the derived abundances are typically <~0.05dex. The stars in our sample have all been previously shown to have abundances that correlate with the condensation temperature (T_c_) of the elements in the sense of increasing abundances with increasing T_c_; these trends have been interpreted as evidence that the stars may have accreted H-depleted planetary material. Our newly derived abundances also correlate positively with T_c_, although slopes of linear least-square fits to the [m/H]-T_c_ relations for all but two stars are smaller here than in previous studies. When considering the refractory elements (T_c_>900K) only, which may be more sensitive to planet formation processes, the sample can be separated into a group with positive slopes (four stars) and a group with flat or negative slopes (six stars). The four stars with positive slopes have very close-in giant planets (three at 0.05AU) and slopes that fall above the general Galactic chemical evolution trend. We suggest that these stars have accreted refractory-rich planet material but not to the extent that would increase significantly the overall stellar metallicity. The flat or negative slopes of the remaining six stars are consistent with recent suggestions of a planet formation signature, although we show that the trends may be the result of Galactic chemical evolution.

Limit your search

more »

more »

more »

more »

more »

more »

more »

more »