The Pristine survey - IX. CFHT ESPaDOnS spectroscopic analysis of 115 bright metal-poor candidate stars

Kim A. Venn*, Collin L. Kielty, Federico Sestito, Else Starkenburg, Nicolas Martin, David S. Aguado, Anke Arentsen, Piercarlo Bonifacio, Elisabetta Caffau, Vanessa Hill, Pascale Jablonka, Carmela Lardo, Lyudmilla Mashonkina, Julio F. Navarro, Chris Sneden, Guillaume Thomas, Kris Youakim, Jonay I. González-Hernández, Rubén Sánchez Janssen, Ray CarlbergKhyati Malhan

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

15 Citations (Scopus)

Abstract

A chemo-dynamical analysis of 115 metal-poor candidate stars selected from the narrow-band Pristine photometric survey is presented based onCFHT high-resolution ESPaDOnS spectroscopy. We have discovered 28 new bright (V < 15) stars with [Fe/H] < -2.5 and 5 with [Fe/H] <-3.0 for success rates of 40 (28/70) and 19 per cent (5/27),respectively. A detailed model atmosphere analysis is carried out for the 28 new metal-poor stars. Stellar parameters were determined fromSDSS photometric colours, Gaia DR2 parallaxes, MESA/MIST stellar isochrones, and the initial Pristine survey metallicities, following aBayesian inference method. Chemical abundances are determined for 10elements (Na, Mg, Ca, Sc, Ti, Cr, Fe, Ni, Y, and Ba). Most stars show chemical abundance patterns that are similar to the normal metal-poor stars in the Galactic halo; however, we also report the discoveries of anew r-process-rich star, a new CEMP-s candidate with [Y/Ba] > 0, and a metal-poor star with very low [Mg/Fe]. The kinematics and orbits for all of the highly probable metal-poor candidates are determined by combining our precision radial velocities with Gaia DR2 proper motions.Some stars show unusual kinematics for their chemistries, including planar orbits, unbound orbits, and highly elliptical orbits that plunge deeply into the Galactic bulge (Rperi < 0.5 kpc); also, eight stars have orbital energies and actions consistent with theGaia-Enceladus accretion event. This paper contributes to our understanding of the complex chemo-dynamics of the metal-poor Galaxy, and increases the number of known bright metal-poor stars available for detailed nucleosynthetic studies.
Original languageEnglish
Pages (from-to)3241-3262
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Volume492
Issue number3
DOIs
Publication statusPublished - Mar-2020
Externally publishedYes

Keywords

  • Galaxy: stellar content
  • Galaxy: kinematics and dynamics
  • Galaxy: abundances
  • stars: Population II
  • stars: abundances
  • stars: kinematics and dynamics

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