The R-Process Alliance: Spectroscopic Follow-up of Low-Metallicity Star Candidates from the Best & Brightest Survey

Abstract

We present results from an observing campaign to identify low-metallicity stars in the Best & Brightest Survey. From medium-resolution (R ~ 1, 200 - 2, 000) spectroscopy of 857 candidates, we estimate the stellar atmospheric parameters (Teff, log g, and [Fe/H]), as well as carbon and alpha-element abundances. We find that 69% of the observed stars have [Fe/H] <= -1.0, 39% have [Fe/H] <= -2.0, and 2% have [Fe/H] <= -3.0. There are also 133 carbon-enhanced metal-poor (CEMP) stars in this sample, with 97 CEMP Group I and 36 CEMP Group II stars identified in the A(C) versus [Fe/H] diagram. A subset of the confirmed low-metallicity stars were followed-up with high-resolution spectroscopy, as part of the R-process Alliance, with the goal of identifying new highly and moderately r-process-enhanced stars. Comparison between the stellar atmospheric parameters estimated in this work and from high-resolution spectroscopy exhibit good agreement, confirming our expectation that medium-resolution observing campaigns are an effective way of selecting interesting stars for further, more targeted, efforts.

arXiv comment57 pages, accepted for publication in ApJ

References in corpus (61)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• Multi-messenger Observations of a Binary Neutron Star Merger
• The Dartmouth Stellar Evolution Database
• The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)
• The Radial Velocity Experiment (RAVE): first data release
• Light Curves of the Neutron Star Merger GW170817/SSS17a: Implications for R-Process Nucleosynthesis
• An absolutely calibrated effective temperature scale from the InfraRed Flux Method
• The SEGUE Stellar Parameter Pipeline. I. Description and Initial Validation Tests
• The RAdial Velocity Experiment (RAVE): Fourth data release
• A single low-energy, iron-poor supernova as the source of metals in the star SMSS J 031300.36-670839.3
• Early Spectra of the Gravitational Wave Source GW170817: Evolution of a Neutron Star Merger
• Carbon-Enhanced Metal-Poor Star Frequencies in the Galaxy: Corrections for the Effect of Evolutionary Status on Carbon Abundances
• The SEGUE Stellar Parameter Pipeline. II. Validation with Galactic Globular and Open Clusters
• The H II Region of the First Star
• Segue 1: An Unevolved Fossil Galaxy from the Early Universe
• The Most Metal-Poor Stars. IV. The Two Populations With [Fe/H] < -3.0
• Observational Constraints on First-Star Nucleosynthesis. I. Evidence for Multiple Progenitors of CEMP-no Stars
• TOPoS: II. On the bimodality of carbon abundance in CEMP stars. Implications on the early chemical evolution of galaxies
• From Nuclei to the Cosmos: Tracing Heavy-Element Production with the Oldest Stars
• The $R$-Process Alliance: First Release from the Southern Search for $r$-Process-Enhanced Stars in the Galactic Halo
• Carbon-enhanced Metal-poor Stars in SDSS/SEGUE. I. Carbon Abundance Estimation and Frequency of CEMP Stars
• Carbon-enhanced metal-poor stars: the most pristine objects?
• An Elemental Assay of Very, Extremely, and Ultra Metal-Poor Stars
• New Hubble Space Telescope Observations of Heavy Elements in Four Metal-Poor Stars
• The R-Process Alliance: First Release from the Northern Search for r-Process Enhanced Metal-Poor Stars in the Galactic Halo
• The SEGUE Stellar Parameter Pipeline. V. Estimation of Alpha-Element Abundance Ratios From Low-Resolution SDSS/SEGUE Stellar Spectra
• The stellar content of the Hamburg/ESO survey. V. The metallicity distribution function of the Galactic halo
• Connecting the first galaxies with ultra faint dwarfs in the Local Group: chemical signatures of Population~III stars
• The Most Metal-Poor Stars. III. The Metallicity Distribution Function and CEMP Fraction
• Descendants of the first stars: the distinct chemical signature of second generation stars
• The Best and Brightest Metal-Poor Stars
• The role of binaries in the enrichment of the early Galactic halo. II. Carbon-Enhanced Metal-Poor Stars - CEMP-no stars
• The R-Process Alliance: A Comprehensive Abundance Analysis of HD 222925, a Metal-Poor Star with an Extreme R-Process Enhancement of [Eu/H] = -0.14
• Nucleosynthesis in a Primordial Supernova: Carbon and Oxygen Abundances in SMSS J031300.36-670839.31
• Population Studies. XIII. A New Analysis of the Bidelman-MacConnell "Weak-Metal" Stars - Confirmation of Metal-Poor Stars in the Thick Disk of the Galaxy
• Metal-Poor Stars Observed with the Magellan Telescope. III. New Extremely and Ultra Metal-Poor Stars from SDSS/SEGUE and Insights on the Formation of Ultra Metal-Poor Stars
• The R-Process Alliance: 2MASS J09544277+5246414, the Most Actinide-Enhanced R-II Star Known
• 3D NLTE analysis of the most iron-deficient star, SMSS0313-6708
• Chemical Analysis of the Ninth Magnitude Carbon-Enhanced Metal-Poor Star BD+44 493
• Metal-poor star formation triggered by the feedback effects from Pop III stars
• RAVE J203843.2-002333: The first highly r-process-enhanced star identified in the RAVE survey
• Galactic Archeology with the AEGIS Survey: The Evolution of Carbon and Iron in the Galactic Halo
• Observational Constraints on First-Star Nucleosynthesis. II. Spectroscopy of an Ultra Metal-Poor CEMP-no Star
• Bright Metal-Poor Stars from the Hamburg/ESO Survey. II. A Chemodynamical Analysis
• The Pristine survey III: Spectroscopic confirmation of an efficient search for extremely metal-poor stars
• New Detections of Arsenic, Selenium, and Other Heavy Elements in Two Metal-Poor Stars
• Constraining cosmic scatter in the Galactic halo through a differential analysis of metal-poor stars
• Detection of the Second r-process Peak Element Tellurium in Metal-Poor Stars
• Chemistry of the Most Metal-poor Stars in the Bulge and the z > 10 Universe
• Classification of extremely metal-poor stars: absent region in A(C)-[Fe/H] plane and the role of dust cooling
• Hubble Space Telescope Near-Ultraviolet Spectroscopy of the Bright CEMP-no Star BD+44 493
• Hubble Space Telescope Near-Ultraviolet Spectroscopy of Bright CEMP-s Stars
• A new candidate for probing Population III nucleosynthesis with carbon-enhanced damped Lyman-alpha systems
• The r-Process Pattern of a Bright, Highly r-Process-Enhanced, Metal-Poor Halo Star at [Fe/H] ~ -2
• Spectroscopic Validation of Low-Metallicity Stars from RAVE
• G64-12 and G64-37 are Carbon-Enhanced Metal-Poor Stars
• The R-Process Alliance: Discovery of the first metal-poor star with a combined r- and s-process element signature
• Detection of Phosphorus, Sulphur, and Zinc in the Carbon-Enhanced Metal-Poor Star BD+44 493
• KOSMOS and COSMOS: New facility instruments for the NOAO 4-meter telescopes
• The universality of the rapid neutron-capture process revealed by a possible disrupted dwarf galaxy star

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• The miniJPAS survey: a preview of the Universe in 56 colours
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• On the inconsistency of [C/Fe] abundances and the fractions of carbon-enhanced metal-poor stars among various stellar surveys
• Dynamically Tagged Groups of Metal-Poor Stars from the Best \& Brightest Survey
• The R-Process Alliance: The Peculiar Chemical Abundance Pattern of RAVE J183013.5-455510
• The Pristine Inner Galaxy Survey (PIGS) III: carbon-enhanced metal-poor stars in the bulge
• The R-Process Alliance: Chemo-Dynamically Tagged Groups II. An Extended Sample of Halo $r$-Process-Enhanced Stars
• Phase-space Properties and Chemistry of the Sagittarius Stellar Stream Down to the Extremely Metal-poor ($[Fe/H]\lesssim -3$) Regime
• Targeting Bright Metal-poor Stars in the Disk and Halo Systems of the Galaxy
• Evidence of First Stars-enriched Gas in High-redshift Absorbers
• The R-Process Alliance: Fifth Data Release from the Search for R-Process-Enhanced Metal-poor Stars in the Galactic Halo with the GTC
• Metal-Poor Stars Observed with the Southern African Large Telescope
• Mining S-PLUS for Metal-Poor Stars in the Milky Way
• The Pristine survey XIV: chemical analysis of two ultra-metal-poor stars
• The S-PLUS Ultra-Short Survey: first data release
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