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Li abundances in the bulk of low-mass metal-poor stars are well reproduced by stellar evolution models adopting a constant initial abundance. However, a small number of stars have exceptionally high Li abundances, for which no convincing…

Solar and Stellar Astrophysics · Physics 2018-01-31 Haining Li , Wako Aoki , Tadafumi Matsuno , Yerra Bharat Kumar , Jianrong Shi , Takuma Suda , Gang Zhao

The chemical fingerprints of the first stars are retained within the photospheres of ancient unevolved metal-poor stars. A significant fraction of these stellar fossils is represented by stars known as Carbon-Enhanced Metal-Poor (CEMP),…

Astrophysics of Galaxies · Physics 2023-04-05 Giulia Pagnini , Stefania Salvadori , Martina Rossi , David Aguado , Ioanna Koutsouridou , Ása Skúladóttir

A sample of mostly old metal-rich dwarf and turn-off stars with high eccentricity and low maximum height above the Galactic plane has been identified. From their kinematics, it was suggested that the inner disk is their most probable…

Solar and Stellar Astrophysics · Physics 2011-09-29 M. Trevisan , B. Barbuy , K. Eriksson , B. Gustafsson , M. Grenon , L. Pompéia

The first stars fundamentally transformed the early Universe through their production of energetic radiation and the first heavy chemical elements. The impact on cosmic evolution sensitively depends on their initial mass function (IMF),…

Astrophysics · Physics 2009-11-13 Anna Frebel , Jarrett L. Johnson , Volker Bromm

Iron, the Universe's most abundant refractory element, is highly depleted in both circumstellar and interstellar environments, meaning it exists in solid form. The nature of this solid is unknown. In this Letter, we provide evidence that…

Dwarf spheroidal galaxies are often conjectured to be the sites of the first stars. The best current contenders for finding the chemical imprints from the enrichment by those massive objects are the "ultrafaint dwarfs" (UFDs). Here we…

Astrophysics of Galaxies · Physics 2015-06-05 Andreas Koch , Francesca Matteucci , Sofia Feltzing

We identified globular clusters and field stars of extragalactic origin and investigated their chemical, physical, and kinematical properties. This objects as supposed was captured by the Galaxy at different times from debris of the dwarf…

Astrophysics · Physics 2009-04-08 V. A. Marsakov , T. V. Borkova

Globular clusters contain many stars with surface abundance patterns indicating contributions from hydrogen burning products, as seen in the anti-correlated elemental abundances of e.g. sodium and oxygen, and magnesium and aluminium.…

Solar and Stellar Astrophysics · Physics 2013-02-05 Robert G. Izzard , Selma E. de Mink , Onno R. Pols , Norbert Langer , Hugues Sana , Alex de Koter

The stellar record of elemental abundances in satellite galaxies is important to identify the origin of r-process because such a small stellar system could have hosted a single r-process event, which would distinguish member stars that are…

Solar and Stellar Astrophysics · Physics 2017-11-29 Takuji Tsujimoto , Tadafumi Matsuno , Wako Aoki , Miho N. Ishigaki , Toshikazu Shigeyama

The emergence of the first sources of light at redshifts of z ~ 10-30 signaled the transition from the simple initial state of the Universe to one of increasing complexity. We review recent progress in our understanding of the formation of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Torgny Karlsson , Volker Bromm , Joss Bland-Hawthorn

The most metal-poor stars in the Milky Way witnessed the early phases of formation of the Galaxy, and have chemical compositions that are close to the pristine mixture from Big Bang nucleosynthesis, polluted by one or few supernovae. Only…

The advent of m class telescopes has allowed the detailed spectroscopic study of sizeable numbers of extremely metal-poor Galactic stars which are the witnesses of the formation of the early Galaxy. Their chemical composition displays some…

Astrophysics · Physics 2009-11-11 Piercarlo Bonifacio

We present a metallicity analysis of 83 late-type giants within the central 1 pc of the Milky Way. K-band spectroscopy of these stars were obtained with the medium-spectral resolution integral-field spectrograph NIFS on Gemini North using…

Astrophysics of Galaxies · Physics 2017-11-20 Tuan Do , Wolfgang Kerzendorf , Nathan Winsor , Morten Støstad , Mark R. Morris , Jessica R. Lu , Andrea M. Ghez

Chemically peculiar stars define a class of stars that show unusual elemental abundances due to stellar photospheric effects and not due to natal variations. In this paper, we compare the elemental abundance patterns of the ultra metal-poor…

Astrophysics · Physics 2009-11-13 K. A. Venn , D. L. Lambert

The external pollution of the first stars in the Galaxy is investigated. The first stars were born in clouds composed of the pristine gas without heavy elements. These stars accreted gas polluted with heavy elements while they still…

Astrophysics · Physics 2009-11-07 Toshikazu Shigeyama , Takuji Tsujimoto , Yuzuru Yoshii

There is ample evidence in the Milky Way for globular cluster (GC) disruption. Hence one may expect that also part of the Galactic halo field stars may once have formed in GCs. We quantify the fraction of halo stars donated by GCs by…

Astrophysics of Galaxies · Physics 2019-05-15 Andreas Koch , Eva K. Grebel , Sarah L. Martell

The chemical elements are created in nuclear fusion processes in the hot and dense cores of stars. The energy generated through nucleosynthesis allows stars to shine for billions of years. When these stars explode as massive supernovae, the…

Solar and Stellar Astrophysics · Physics 2014-08-22 Anna Frebel

The Milky Way ultra-faint dwarf galaxies (UFDs) contain some of the oldest, most metal-poor stars in the Universe. We present [Mg/Fe], [Si/Fe], [Ca/Fe], [Ti/Fe], and mean [alpha/Fe], abundance ratios for 61 individual red giant branch stars…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Luis C. Vargas , Marla Geha , Evan N. Kirby , Joshua D. Simon

Most stars in our Galaxy with photospheric C/O>1 (carbon stars) are not giants but dwarfs. The newly-recognized class of dwarf carbon (dC) stars joins the growing family of stars with peculiar abundances that are now recognized as products…

Astrophysics · Physics 2007-05-23 Paul J. Green

The $r$-process-enhanced (RPE) stars provide fossil records of the assembly history of the Milky Way and the nucleosynthesis of the heaviest elements. Observations by the $R$-Process Alliance (RPA) and others have confirmed that many RPE…

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