Carbon-Enhanced Metal-Poor Stars: CEMP-s and CEMP-no Sub-Classes in the Halo System of the Milky Way

Abstract

We explore the kinematics and orbital properties of a sample of 323 very metal-poor stars in the halo system of the Milky Way, selected from the high-resolution spectroscopic follow-up studies of Aoki et al. and Yong et al. The combined sample contains a significant fraction of carbon-enhanced metal-poor (CEMP) stars (22% or 29%, depending on whether a strict or relaxed criterion is applied for this definition). Barium abundances (or upper limits) are available for the great majority of the CEMP stars, allowing for their separation into the CEMP-$s$ and CEMP-no sub-classes. A new method to assign membership to the inner- and outer-halo populations of the Milky Way is developed, making use of the integrals of motion, and applied to determine the relative fractions of CEMP stars in these two sub-classes for each halo component. Although limited by small-number statistics, the data suggest that the inner halo of the Milky Way exhibits a somewhat higher relative number of CEMP-$s$ stars than CEMP-no stars (57% vs. 43%), while the outer halo possesses a clearly higher fraction of CEMP-no stars than CEMP-$s$ stars (70% vs. 30%). Although larger samples of CEMP stars with known Ba abundances are required, this result suggests that the dominant progenitors of CEMP stars in the two halo components were different; massive stars for the outer halo, and intermediate-mass stars in the case of the inner halo.

23 pages (apj format), 4 Figures, Accepted for publication on the Astrophysical Journal (Figure 3: label replaced)

References in corpus (16)

• The 2.5 m Telescope of the Sloan Digital Sky Survey
• Two Stellar Components in the Halo of the Milky Way
• Nucleosynthetic signatures of the first stars
• Carbon Enhanced Metal-Poor Stars. I. Chemical Compositions of 26 Stars
• The Milky Way's circular velocity curve between 4 and 14 kpc from APOGEE data
• A single low-energy, iron-poor supernova as the source of metals in the star SMSS J 031300.36-670839.3
• The Dual Origin of Stellar Halos
• An extremely primitive halo star
• The large-scale structure of the halo of the Andromeda Galaxy Part I: global stellar density, morphology and metallicity properties
• HE 0557-4840 - Ultra-Metal-Poor and Carbon-Rich
• Think Outside the Color Box: Probabilistic Target Selection and the SDSS-XDQSO Quasar Targeting Catalog
• The Frequency of Carbon-Enhanced Metal-Poor Stars in the Galaxy from the HERES sample
• The stellar content of the Hamburg/ESO survey. IV. Selection of candidate metal-poor stars
• Bright Metal-Poor Stars from the Hamburg/ESO Survey. I. Selection and Follow-up Observations from 329 Fields
• Carbon-Enhanced Metal-Poor Stars, the Cosmic Microwave Background, and the Stellar IMF in the Early Universe
• Metallicity Bias in the Kinematics of the Milky Way Stellar Halo

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• The Pristine survey I: Mining the Galaxy for the most metal-poor stars
• 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
• Binarity in Carbon-Enhanced Metal-Poor stars
• Carbon, oxygen, and iron abundances in disk and halo stars. Implications of 3D non-LTE spectral line formation
• The role of binaries in the enrichment of the early Galactic halo. II. Carbon-Enhanced Metal-Poor Stars - CEMP-no stars
• White dwarf evolutionary sequences for low-metallicity progenitors: The impact of third dredge-up
• Exploring the Origin of Lithium, Carbon, Strontium and Barium with four new Ultra Metal-Poor Stars
• Carbon-Enhanced Metal-Poor Stars: Relics from the Dark Ages
• 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
• The oldest and most metal poor stars in the APOSTLE Local Group simulations
• CO/H2, C/CO, OH/CO, and OH/O2 in Dense Interstellar Gas: From High Ionization to Low Metallicity
• Evidence for an aspherical Population III supernova explosion inferred from the hyper metal-poor star HE1327-2326
• Nine New Metal-Poor Stars on the Subgiant and Red Horizontal Branches with High Levels of r-process Enhancement
• Metal-poor stars towards the Galactic bulge - a population potpourri
• Galactic Archeology with the AEGIS Survey: The Evolution of Carbon and Iron in the Galactic Halo
• Bright Metal-Poor Stars from the Hamburg/ESO Survey. II. A Chemodynamical Analysis
• Dynamically Tagged Groups of Very Metal-poor Halo Stars from the HK and Hamburg/ESO Surveys
• Abundances and kinematics of carbon-enhanced metal-poor stars in the Galactic halo*; A new classification scheme based on Sr and Ba
• Abundances of carbon-enhanced metal-poor stars as constraints on their formation
• High-resolution spectroscopic studies of ultra metal-poor stars found in LAMOST survey
• The Fractions of Inner- and Outer-Halo Stars in the Local Volume
• The Most Metal-Poor Stars. V. The CEMP-no Stars in 3D and Non-LTE
• Chemical Cartography. I. A Carbonicity Map of the Galactic Halo
• G64-12 and G64-37 are Carbon-Enhanced Metal-Poor Stars
• On the inconsistency of [C/Fe] abundances and the fractions of carbon-enhanced metal-poor stars among various stellar surveys
• Metal-poor stars observed with the automated planet finder telescope. I. Discovery of five carbon-enhanced metal-poor stars from LAMOST
• Metal-poor Stars Observed with the Automated Planet Finder Telescope. II. Chemodynamical Analysis of Six Low-Metallicity Stars in the Halo System of the Milky Way
• The Pristine Inner Galaxy Survey (PIGS) III: carbon-enhanced metal-poor stars in the bulge
• Chemical Cartography. II. The Assembly History of the Galactic Stellar Halo Traced by Carbon-Enhanced Metal-Poor Stars
• Stellar winds and metal enrichment from fast-rotating Population III stars
• The low Sr/Ba ratio on some extremely metal-poor stars
• Chemo-Dynamically Tagged Groups of CEMP Stars in the Halo of the Milky Way. I. Untangling the Origins of CEMP-$s$ and CEMP-no Stars
• Carbon-Enhanced Metal-Poor star candidates from BP/RP Spectra in $Gaia$ DR3
• Identification of a Group III CEMP-no Star in the Dwarf Spheroidal Galaxy Canes Venatici I
• Targeting Bright Metal-poor Stars in the Disk and Halo Systems of the Galaxy
• Jurassic: A Chemically Anomalous Structure in the Galactic Halo
• The chemical signature of surviving Population III stars in the Milky Way
• The R-Process Alliance: Fifth Data Release from the Search for R-Process-Enhanced Metal-poor Stars in the Galactic Halo with the GTC
• Abundance analysis of a CEMP-no star in the Carina dwarf spheroidal galaxy
• Are Faint Supernovae Responsible for Carbon-Enhanced Metal-Poor Stars?
• Metallicity and Kinematics of the Galactic halo from the LAMOST sample stars
• The Metallicity Gradient and Complex Formation History of the Outermost Halo of the Milky Way
• Investigation of a sample of carbon-enhanced metal-poor stars observed with FORS and GMOS
• The GALAH survey: a catalogue of carbon-enhanced stars and CEMP candidates
• HE 0017+0055 : A probable pulsating CEMP-rs star and long-period binary
• Exploring the Galactic Anticenter substructure with LAMOST & Gaia DR2
• On the dearth of C-enhanced metal-poor stars in the Galactic bulge
• Chemical analysis of two extremely metal-poor stars HE 2148-2039 and HE 2155-2043
• Inhomogeneity in the early Galactic chemical enrichment exposed by beryllium abundances in extremely metal-poor stars
• Are the Formation and Abundances of Metal-Poor Stars the Result of Dust Dynamics?
• Two Populations of Carbon-Enhanced Metal-Poor Stars in the Disk System of the Milky Way
• Carbon-enhanced metal-poor stars in the SDSS-APOGEE database
• CEMPlifying reionization
• A Multiply-Imaged z $\sim$ 6.3 Lyman Alpha Emitter candidate behind Abell 2261
• Galactic Stellar Populations from Photometric Metallicity Distribution Functions
• Implications of time-dependent molecular chemistry in metal-poor dwarf stars