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200 papers

We present initial results measuring the companion fraction of metal-poor stars ([Fe/H]$<-$2.0). We are employing the Lick Observatory planet-finding system to make high-precision Doppler observations of these objects. The binary fraction…

We describe the construction of a database of extremely metal-poor (EMP) stars in the Galactic halo whose elemental abundances have been determined. Our database contains detailed elemental abundances, reported equivalent widths,…

The Galactic stellar halo is predicted to have formed at least partially from the tidal disruption of accreted dwarf galaxies. This assembly history should be detectable in the orbital and chemical properties of stars. The H3 Survey is…

We present Keck/HIRES observations of six metal-poor stars in two of the ultra-faint dwarf galaxies orbiting the Milky Way, Ursa Major II and Coma Berenices. These observations include the first high-resolution spectroscopic observations of…

Astrophysics of Galaxies · Physics 2009-12-17 Anna Frebel , Joshua D. Simon , Marla Geha , Beth Willman

We report the discovery of eight new extremely metal-poor galaxies (XMPGs; 12+log(O/H) < 7.65) and the recovery of four previously known or suspected XMPGs (IZw18, HS0822+3542, HS0837+4717 and A1116+517) using Sloan Digital Sky Survey…

The goal of this paper is to present and analyse a new sample of cool carbon (C)stars located in the halo. Twenty three new C stars were discovered. Spectra are typical of N-type stars with C2 and CN bands and sometimes Halpha in emission.…

Astrophysics · Physics 2009-11-13 N. Mauron , K. S. Gigoyan , T. R. Kendall

Wide angle and deep surveys, regardless of their primary purpose, always sample a large number of stars in the Galaxy and in its satellite system. We here make a forecast of the expected stellar sample resulting from the Dark Energy Survey…

Stellar metallicity strongly correlates with the presence of planets and their properties. To check for new correlations between stars and the existence of an orbiting planet, we determine precise stellar parameters for a sample of…

Solar and Stellar Astrophysics · Physics 2015-05-20 Sérgio G. Sousa , Nuno C. Santos , Garik Israelian , C. Lovis , Michel Mayor , Pedro B. Silva , Stephane Udry

We performed an extensive non-LTE analysis of the neutral sodium lines of Na {\sc i} 5683/5688, 5890/5896, 6154/6161, and 8183/8195 for disk/halo stars of F--K type covering a wide metallicity range ($-4 \la$ [Fe/H] $\la 0.4$), based on our…

Astrophysics · Physics 2014-10-13 Yoichi Takeda , Gang Zhao , Masahide Takada-Hidai , Yu-Qin Chen , Yu-ji Saito , Hua-Wei Zhang

We report on the discovery of 28 $z\approx0.8$ metal-poor galaxies in DEEP2. These galaxies were selected for their detection of the weak [OIII]$\lambda$4363 emission line, which provides a "direct" measure of the gas-phase metallicity. A…

Astrophysics of Galaxies · Physics 2015-05-27 Chun Ly , Jane Rigby , Michael Cooper , Renbin Yan

We report a detailed abundance analysis for HE0107-5240, a halo giant with [Fe/H]_NLTE=-5.3. This star was discovered in the course of follow-up medium-resolution spectroscopy of extremely metal-poor candidates selected from the digitized…

We present the results of a detailed abundance analysis of one of the confirmed building blocks of the Milky Way stellar halo, a kinematically-coherent metal-poor stellar stream. We have obtained high resolution and high S/N spectra of 12…

Astrophysics of Galaxies · Physics 2015-05-14 Ian U. Roederer , Christopher Sneden , Ian B. Thompson , George W. Preston , Stephen A. Shectman

The origin of the Galactic halo is one of the fundamental topics linking the study of galaxy formation and evolution to cosmology. We aim at deriving precise and accurate stellar parameters, Mg abundances, and ages for a sample of…

Astrophysics of Galaxies · Physics 2025-06-04 Riano E. Giribaldi , Laura Magrini , Martina Rossi , Anish M. Amarsi , Donatella Romano , Davide Massari

We present the first results of an extensive spectroscopic survey of directly imaged planet host stars. The goal of the survey is the measurement of stellar properties and abundances of 15 elements (including C, O, and S) in these stars. In…

A new set of very high signal-to-noise (S/N > 100/1), medium-resolution (R~3000) optical spectra have been obtained for 302 of the candidate "weak-metal" stars selected by Bidelman & MacConnell. We use these data to calibrate the recently…

We present gas-phase metallicity measurements for 583 emission line galaxies at $0.3<z<0.85$, including 388 dwarf galaxies with $log(M_{\star}/M_{\odot}) < 9.5$, and explore the dependence of the metallicity on the stellar mass and star…

We present new measurements of the abundances of carbon and oxygen derived from high-excitation C I and O I absorption lines in metal-poor halo stars, with the aim of clarifying the main sources of these two elements in the early stages of…

Astrophysics · Physics 2015-05-13 D. Fabbian , P. E. Nissen , M. Asplund , M. Pettini , C. Akerman

We present the third list with results {Tables 2 to 6 are available only in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html. Figures A1 to A9 will be made…

We present 6.5-meter MMT and 3.5m APO spectrophotometry of 69 H II regions in 42 low-metallicity emission-line galaxies, selected from the Data Release 7 of the Sloan Digital Sky Survey to have mostly [O III]4959/Hbeta < 1 and [N…

Cosmology and Nongalactic Astrophysics · Physics 2018-05-29 Y. I. Izotov , T. X. Thuan , N. G. Guseva