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HARPS-N spectra with S/N > 250 and MARCS model atmospheres were used to derive abundances of C, O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zn, and Y in ten stars from the Kepler LEGACY sample (including the binary pair 16 Cyg A and B) selected…

Solar and Stellar Astrophysics · Physics 2017-12-13 P. E. Nissen , V. Silva Aguirre , J. Christensen-Dalsgaard , R. Collet , F. Grundahl , D. Slumstrup

The present study of spectra of twelve metal-rich cool dwarf stars, carefully selected in order to cover a range of temperatures (~4400 - 6000 K), is a follow up on Feltzing & Gustafsson (1998, A&AS 129, 237) with the aim to understand the…

Astrophysics · Physics 2007-05-23 P. Thoren , S. Feltzing

We studied the relationship between the average stellar abundance of several elements and the orbital evolution of stars in the neighbourhood of the Sun, using both observational data for 325 late-type dwarfs in a volume-complete sample and…

Using high-resolution spectra of nearby F and G dwarf stars, we have investigated the detailed abundance and age structure of the Hercules stream. We find that the stars in the stream have a wide range of stellar ages, metallicities, and…

Astrophysics · Physics 2009-11-11 T. Bensby , M. S. Oey , S. Feltzing , B. Gustafsson

We present isochrone ages and initial bulk metallicities ($\rm [Fe/H]_{bulk}$, by accounting for diffusion) of 163,722 stars from the GALAH Data Release 2, mainly composed of main sequence turn-off stars and subgiants ($\rm 7000…

We determine detailed elemental abundances in stars belonging to the so-called Group 1 of the Geneva-Copenhagen survey (GCS) and compare the chemical composition with the Galactic thin- and thick-disc stars, with the GCS Group 2 and Group 3…

Solar and Stellar Astrophysics · Physics 2015-06-23 R. Ženovienė , G. Tautvaišienė , B. Nordström , E. Stonkutė , G. Barisevičius

We have analyzed high-resolution and high signal-to-noise ratio optical spectra of nearby FGK stars with and without detected giant planets in order to homogeneously measure their photospheric parameters, mass, age, and the abundances of…

Solar and Stellar Astrophysics · Physics 2015-07-29 R. da Silva , A. C. Milone , H. J. Rocha-Pinto

In this work we present chemical abundances of heavy elements (Z$>$28) for a homogeneous sample of 1059 stars from HARPS planet search program. We also derive ages using parallaxes from Hipparcos and Gaia DR1 to compare the results. We…

Solar and Stellar Astrophysics · Physics 2018-06-13 E. Delgado Mena , M. Tsantaki , V. Zh. Adibekyan , S. G. Sousa , N. C. Santos , J. I. González Hernández , G. Israelian

The chemical abundances of the metal-poor stars in the stellar stream provide important information for setting constraints on models of neutron-capture processes. The study of these stars could give us a better understanding of r-process…

Solar and Stellar Astrophysics · Physics 2015-06-11 Hongjie Li , Shuai Liang , Wenyuan Cui , Bo Zhang

Aims. The Chemical Evolution of R-process Elements in Stars (CERES) project aims to provide a homogeneous analysis of a sample of metal-poor stars ([Fe/H]<-1.5). We present the stellar parameters and the chemical abundances of elements up…

For the first time, we present an extensive study of stars with individual non-local thermodynamic equilibrium (NLTE) abundances for 17 chemical elements from Li to Eu in a sample of stars uniformly distributed over the $-2.62 \le$ [Fe/H]…

We conducted an investigation on the chemical abundances of 4,316 stars in the red giant branch (RGB) phase from the recently released APO-K2 catalogue. Our aim was to characterize the abundance trends of the single elements with…

Astrophysics of Galaxies · Physics 2024-07-09 G. Valle , M. Dell'Omodarme , P. G. Prada Moroni , S. Degl'Innocenti

We have previously reported on chemical abundance trends with evolutionary state in the globular cluster NGC 6397 discovered in analyses of spectra taken with FLAMES at the VLT. Here, we reinvestigate the FLAMES-UVES sample of 18 stars,…

Solar and Stellar Astrophysics · Physics 2012-09-24 T. Nordlander , A. J. Korn , O. Richard , K. Lind

Abundances of 18 elements are determined for the common proper-motion pair, HD134439 and HD134440, which shows high [Mn/Fe] and low [\alpha/Fe] ratios as compared to normal halo stars. Moreover, puzzling abundances are indicated from…

Astrophysics · Physics 2009-11-11 Y. Q. Chen , G. Zhao

Recent theoretical yields and chemical evolution models demonstrate that intermediate-mass AGB stars cannot reproduce the observed abundance distributions of O, Na, Mg, and Al. As a further observational test of this finding, we present…

We use our new, flux-calibrated stellar population model of absorption-line indices to derive ages, metallicities, and various element abundance ratios from integrated light spectroscopy of galactic globular clusters. The ages agree well…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Daniel Thomas , Jonas Johansson , Claudia Maraston

Observations of the Milky Way's low-$\alpha$ disk show that at fixed metallicity, [Fe/H], several element abundance, [X/Fe], correlate with age, with unique slopes and small scatters around the age-[X/Fe] relations. In this study, we turn…

Oxygen abundances of 67 dwarf stars in the metallicity range -1.6<[Fe/H]<-0.4 are derived from a non-LTE analysis of the 777 nm O I triplet lines. These stars have precise atmospheric parameters measured by Nissen and Schuster, who find…

Solar and Stellar Astrophysics · Physics 2015-06-11 I. Ramirez , J. Melendez , J. Chaname

Chemical abundances for 15 elements (C, N, O, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, and Ni) are presented for 83 stellar members of the 4 Gyr old solar-metallicity open cluster M67. The sample contains stars spanning a wide range of…

We identified 8 additional stars as members of the Helmi stream (HStr) in the combined GALAH+ DR3 and $Gaia$ EDR3 catalog. By consistently reevaluating claimed members from the literature, we consolidate a sample of 22 HStr stars with…