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We have investigated the abundance of several chemical elements in two large stellar samples kinematically representative of the thin and the thick disks of the Galaxy. Chemical, kinematical and age data have been collected from high…

Astrophysics · Physics 2007-05-23 Pascal Girard , Caroline Soubiran

Using the DR12 public release of APOGEE data, we show that thin and thick disk separate very well in the space defined by [$\alpha$/Fe], [Fe/H] and [C/N]. Thick disk giants have both higher [C/N] and higher [$\alpha$/Fe] than do thin disk…

Solar and Stellar Astrophysics · Physics 2015-09-03 T. Masseron , G. Gilmore

Context. The presence of [$\alpha$/Fe]-[Fe/H] bi-modality in the Milky Way disc has animated the Galactic archaeology community since more than two decades. Aims. Our goal is to investigate the chemical, temporal, and kinematical structure…

We have studied 23 long-lived G dwarfs that belong to the thin disk and thick disk stellar populations. Abundances have been derived for 24 elements: O, Na, Mg, Al, Si, Ca, Ti, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Nd,…

Astrophysics · Physics 2008-11-26 Mary-Margaret Brewer , Bruce W. Carney

To understand the formation and evolution of the different stellar populations within our Galaxy it is essential to combine detailed kinematical and chemical information for large samples of stars. We derive chemical abundances of Cu, Zn,…

Solar and Stellar Astrophysics · Physics 2017-10-25 E. Delgado Mena , M. Tsantaki , V. Zh. Adibekyan , S. G. Sousa , N. C. Santos , J. I. González Hernández , G. Israelian

Solar twins are stars with similar stellar (surface) parameters to the Sun that can have a wide range of ages. This provide an opportunity to analyze the variation of their chemical abundances with age. Nissen (2015) recently suggested that…

Solar and Stellar Astrophysics · Physics 2016-05-04 M. Tucci Maia , I. Ramírez , J. Meléndez , M. Bedell , J. L. Bean , M. Asplund

From a detailed elemental abundance analysis of 102 F and G dwarf stars we present abundance trends in the Galactic thin and thick disks for 14 elements (O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zn, Y, Ba, and Eu). Stellar parameters and…

Astrophysics · Physics 2007-05-23 T. Bensby , S. Feltzing , I. Lundström , I. Ilyin

The heavy elements (Z>30) are created in neutron-capture processes which happen at very different nucleosynthetic sites. To study them in an environment different from the Milky Way, we target these elements in RGB stars in the Sculptor…

Astrophysics of Galaxies · Physics 2019-11-20 Ása Skúladóttir , Camilla Juul Hansen , Stefania Salvadori , Arthur Choplin

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 properties of the relative abundances of rapid and slow neutron-capture elements are studied using a catalog containing spectroscopic abundance determinations for 14~elements produced in various nuclear-synthesis processes for 90~open…

Astrophysics of Galaxies · Physics 2016-02-22 V. A. Marsakov , M. L. Gozha , V. V. Koval' , L. V. Shpigel'

We calculate the evolution of heavy element abundances from C to Zn in the solar neighborhood adopting our new nucleosynthesis yields. Our yields are calculated for wide ranges of metallicity (Z=0-Z_\odot) and the explosion energy (normal…

Astrophysics · Physics 2008-11-26 C. Kobayashi , H. Umeda , K. Nomoto , N. Tominaga , T. Ohkubo

Abundance observations indicate the presence of rapid-neutron capture (i.e., r-process) elements in old Galactic halo and globular cluster stars. These observations demonstrate that the earliest generations of stars in the Galaxy,…

Astrophysics · Physics 2009-11-06 J. J. Cowan , C. Sneden , J. W. Truran

Oxygen and carbon are important elements in stellar populations. Their behavior refers to the formation history of the stellar populations. C and O abundances would also obviously influence stellar opacities and the overall metal abundance…

Solar and Stellar Astrophysics · Physics 2016-12-21 Z. S. Ge , S. L. Bi , Y. Q. Chen , T. D. Li , J. K. Zhao , K. Liu , Fergusion J. W. , Y. Q. Wu

We determine relative abundance ratios for the neutron-capture elements Zr, La, Ce, Nd, and Eu for a sample of 27 Galactic dwarf stars with -1.5 < [Fe/H] <-0.8. We also measure the iron-peak element Sc. These stars separate into three…

Solar and Stellar Astrophysics · Physics 2017-01-18 C. K. Fishlock , D. Yong , A. I. Karakas , A. Alves-Brito , J. Melendez , P. E. Nissen , C. Kobayashi , A. R. Casey

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 follow the Galactic enrichment of three easily observed light n-capture elements Sr,Y,and Zr.Input stellar yields have been first separated into their respective main and weak s-process,and r-process components.The s-process yields from…

HARPS spectra with signal-to-noise ratios S/N > 600 at 6000 A were analysed with MARCS model atmospheres to obtain 1D LTE abundances of C, O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Sr, and Y for 72 nearby solar-type stars with metallicities in…

Solar and Stellar Astrophysics · Physics 2020-08-19 P. E. Nissen , J. Christensen-Dalsgaard , J. R. Mosumgaard , V. Silva Aguirre , E. Spitoni , K. Verma.

The oldest stars in the universe retain to a great extent detailed information on the chemical composition of the interstellar medium at the time of their birth. Hence the earliest phases of Galactic chemical evolution and nucleosynthesis…

Solar and Stellar Astrophysics · Physics 2013-01-31 Terese Hansen , Johannes Andersen , Birgitta Nordtröm

We analyze high quality abundances data of solar neighborhood stars and show that there are two distinct regimes of [alpha/Fe] versus age which we identify as the epochs of the thick and thin disk formation. A tight correlation between…

Astrophysics of Galaxies · Physics 2015-06-16 M. Haywood , P. Di Matteo , M. Lehnert , D. Katz , A. Gomez

We extend our previous work on the age-chemical abundance structure of the Galactic outer disc to the inner disc (4 < r < 8 kpc) based on the SDSS/APOGEE survey. Different from the outer disc, the inner disc stars exhibit a clear bimodal…