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Based on high-resolution spectral observations for a sample of very metal-poor stars, we investigate how well stellar chemical abundances can be derived with available theoretical methods and computational tools.

Solar and Stellar Astrophysics · Physics 2018-08-22 Lyudmila Mashonkina , Tatyana Sitnova , Yuri Pakhomov , Tatyana Ryabchikova

HARPS spectra with S/N > 600 for 21 solar twin stars are used to determine very precise (sigma ~ 0.01 dex) differential abundances of C, O, Na, Mg, Al, Si, S, Ca, Ti, Cr, Fe, Ni, Zn, and Y in order to see how well [X/Fe] is correlated with…

Solar and Stellar Astrophysics · Physics 2015-07-01 Poul E. Nissen

Moderately r-process-enriched stars (r-I) are at least four times as common as those that are greatly enriched in r-process elements (r-II), and the abundances in their atmospheres are important tools for obtaining a better understanding of…

Solar and Stellar Astrophysics · Physics 2015-06-19 C. Siqueira-Mello , V. Hill , B. Barbuy , M. Spite , F. Spite , T. C. Beers , E. Caffau , P. Bonifacio , R. Cayrel , P. François , H. Schatz , S. Wanajo

[Abridged abstract] We have performed an abundance analysis for 176 F- and G- dwarfs of the Galactic thick disk component. Using accurate radial velocities combined with $Hipparcos$ astrometry, kinematics (U, V, and W) and Galactic orbital…

Astrophysics · Physics 2009-11-13 Bacham E. Reddy , David L. Lambert , Carlos Allende Prieto

The determination of photospheric abundances in late-type stars from spectroscopic observations is a well-established field, built on solid theoretical foundations. Improving those foundations to refine the accuracy of the inferred…

Solar and Stellar Astrophysics · Physics 2016-07-27 Carlos Allende Prieto

Using high-resolution echelle spectra obtained with Magellan/MIKE, we present a chemical abundance analysis of both stars in the planet-hosting wide binary system HD20782 + HD20781. Both stars are G dwarfs, and presumably coeval, forming in…

Earth and Planetary Astrophysics · Physics 2015-06-19 Claude E. Mack , Simon C. Schuler , Keivan G. Stassun , Joshua Pepper , John Norris

Bedell et al. (2018) give precision differential abundances for 79 mostly G-dwarf stars. We correct these abundances for Galactic chemical evolution in a manner similar to that used by these authors but with parameters derived from linear…

Solar and Stellar Astrophysics · Physics 2020-04-07 Charles R. Cowley , Donald J. Bord , Kutluay Yüce

We implemented non-solar-scaled opacities in a simultaneous derivation of fundamental parameters and abundances. We carried out a high-precision stellar parameters and abundance determination by applying non-solar-scaled opacities and model…

Solar and Stellar Astrophysics · Physics 2018-12-05 C. Saffe , M. Flores , P. Miquelarena , F. M. Lopez , M. Jaque Arancibia , A. Collado , E. Jofre , R. Petrucci

We discuss the accuracy of the abundance determinations of H II regions in our Galaxy and other galaxies. We focus on the main observational constraints derived from abundance determinations that have implications for models of galactic…

Astrophysics · Physics 2009-10-31 M. Peimbert , L. Carigi , A. Peimbert

Carbon and oxygen abundances in F and G main-sequence stars ranging in metallicity from [Fe/H] = -1.6 to +0.5 are determined from a non-LTE analysis of CI and OI atomic lines in high-resolution spectra. Both C and O are good tracers of…

Astrophysics of Galaxies · Physics 2015-06-16 Poul E. Nissen , William J. Schuster

We present radial velocities, equivalent widths, model atmosphere parameters, and abundances or upper limits for 53 species of 48 elements derived from high resolution optical spectroscopy of 313 metal-poor stars. A majority of these stars…

During the past decade, several studies reported a correlation between chemical abundances of stars and condensation temperature (also known as Tc trend). However, the real astrophysical nature of this correlation is still debated. The main…

We compare the abundances of various chemical species as derived with 3D hydrodynamical and classical 1D stellar atmosphere codes in a late-type giant characterized by T_eff=3640K, log g = 1.0, [M/H] = 0.0. For this particular set of…

Solar and Stellar Astrophysics · Physics 2015-05-14 A. Kucinskas , V. Dobrovolskas , A. Ivanauskas , H. -G. Ludwig , E. Caffau , K. Blazevicius , J. Klevas , D. Prakapavicius

Comparing chemical abundances of a planet and the host star reveals the origin and formation path. Stellar abundance is measured with high-resolution spectroscopy. Planet abundance, on the other hand, is usually inferred from low-resolution…

We compile spectroscopic abundance data from 84 literature sources for 50 elements across 3058 stars in the solar neighborhood, within 150 pc of the Sun, to produce the Hypatia Catalog. We evaluate the variability of the spread in abundance…

Solar and Stellar Astrophysics · Physics 2015-06-19 Natalie R. Hinkel , F. X. Timmes , Patrick A. Young , Michael D. Pagano , Margaret C. Turnbull

The Milky Way harbours two disks that appear distinct concerning scale-heights, kinematics, and elemental abundance patterns. Recent years have seen a surge of studies of the elemental abundance trends in the disks using high resolution…

Astrophysics · Physics 2007-05-23 Sofia Feltzing

[ABRIDGED] The purpose of this work is to evaluate how several elements produced by different nucleosynthesis processes behave with stellar age and provide empirical relations to derive stellar ages from chemical abundances. We derive…

Binary stars hosting exoplanets are a unique laboratory where chemical tagging can be performed to measure with high accuracy the elemental abundances of both stellar components, with the aim to investigate the formation of planets and…

The determination of chemical abundances from stellar spectra is considered a mature field of astrophysics. Digital spectra of stars are recorded and processed with standard techniques, much like samples in the biological sciences.…

Astrophysics · Physics 2007-05-23 C. Allende Prieto

It is argued that the abundances of r-process related elements in stars with -3<[Fe/H]<-1 can be explained by the contributions of three sources. The sources are: the first generations of very massive (>100 solar masses) stars that are…

Astrophysics · Physics 2009-11-06 Y. -Z. Qian , G. J. Wasserburg