Metal-poor stars observed with the automated planet finder telescope. I. Discovery of five carbon-enhanced metal-poor stars from LAMOST

Abstract

We report on the discovery of five carbon-enhanced metal-poor (CEMP) stars in the metallicity range of $-3.3<$ [Fe/H] $<-2.4$. These stars were selected from the LAMOST DR3 low-resolution (R$\sim$ 2,000) spectroscopic database as metal-poor candidates and followed-up with high-resolution spectroscopy (R$\sim$110,000) with the LICK/APF. Stellar parameters and individual abundances for 25 chemical elements (from Li to Eu) are presented for the first time. These stars exhibit chemical abundance patterns that are similar to those reported in other literature studies of very and extremely metal-poor stars. One of our targets, J2114$-$0616, shows high enhancement in carbon ([C/Fe]=1.37), nitrogen ([N/Fe]= 1.88), barium ([Ba/Fe]=1.00), and europium ([Eu/Fe]=0.84). Such chemical abundance pattern suggests that J2114$-$0616 can be classified as CEMP-r/s star. In addition, the star J1054+0528 can be classified as a CEMP-rI star, with [Eu/Fe]=0.44 and [Ba/Fe]=$-$0.52. The other stars in our sample show no enhancements in neutron-capture elements and can be classified as CEMP-no stars. We also performed a kinematic and dynamical analysis of the sample stars based on Gaia DR2 data. The kinematic parameters, orbits, and binding energy of these stars, show that J2114$-$0616 is member of the outer halo population, while the remaining stars belong to the inner halo population but with an accreted origin. Collectively, these results add important constraints on the origin and evolution of CEMP stars as well as on their possible formation scenarios.

References in corpus (91)

• Astropy: A Community Python Package for Astronomy
• The NumPy array: a structure for efficient numerical computation
• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• The chemical composition of the Sun
• Gaia Data Release 2. Summary of the contents and survey properties
• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• First stars V - Abundance patterns from C to Zn and supernova yields in the early Galaxy
• The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)
• The r-process of stellar nucleosynthesis: Astrophysics and nuclear physics achievements and mysteries
• The X-ray counterpart to the gravitational wave event GW 170817
• Kinematics of Metal-Poor Stars in the Galaxy. III. Formation of the Stellar Halo and Thick Disk as Revealed from a Large Sample of Non-Kinematically Selected Stars
• Two Stellar Components in the Halo of the Milky Way
• The effective temperature scale of FGK stars. II. Teff : color : [Fe/H] calibrations
• Nucleosynthetic signatures of the first stars
• Neutron-Capture Elements in the Early Galaxy: Insights from a Large Sample of Metal-Poor Giants
• One Hundred First Stars : Protostellar Evolution and the Final Masses
• Near-Field Cosmology with Metal-Poor Stars
• A stellar relic from the early Milky Way
• Carbon Enhanced Metal-Poor Stars. I. Chemical Compositions of 26 Stars
• Structure and Kinematics of the Stellar Halos and Thick Disks of the Milky Way Based on Calibration Stars from SDSS DR7
• A Search for Stars of Very Low Metal Abundance. VI. Detailed Abundances of 313 Metal-Poor Stars
• The Stellar Abundances for Galactic Archeology (SAGA) Database - Compilation of the Characteristics of Known Extremely Metal-Poor Stars
• First stars VI - Abundances of C, N, O, Li, and mixing in extremely metal-poor giants. Galactic evolution of the light elements
• The Emergence of the Thick Disk in a CDM Universe
• R-process enrichment from a single event in an ancient dwarf galaxy
• A single low-energy, iron-poor supernova as the source of metals in the star SMSS J 031300.36-670839.3
• Spectroscopic Studies of Extremly Metal-Poor Stars with Subaru/HDS:II.The r-process Elements, Including Thorium
• The Dual Origin of Stellar Halos
• The Most Metal-Poor Stars. II. Chemical Abundances of 190 Metal-Poor Stars Including 10 New Stars With [Fe/H] < -3.5
• Early Spectra of the Gravitational Wave Source GW170817: Evolution of a Neutron Star Merger
• An extremely primitive halo star
• First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy
• Departures from LTE for neutral Li in late-type stars
• The Binary Frequency Among Carbon-Enhanced, s-Process Rich, Metal-Poor Stars
• Carbon-Enhanced Metal-Poor Star Frequencies in the Galaxy: Corrections for the Effect of Evolutionary Status on Carbon Abundances
• Where, oh where has the r-process gone?
• The Abundances of Neutron Capture Species in the Very Metal-Poor Globular Cluster M15: An Uniform Analysis of RGB and RHB Stars
• Cosmological simulations of the formation of the stellar haloes around disc galaxies
• Very low metallicity massive star models: Pre-SN evolution and primary nitrogen production
• Four New Stellar Debris Streams in the Galactic Halo
• Effects of rotation on the evolution of primordial stars
• A holistic approach to carbon-enhanced metal-poor stars
• NLTE abundances of Mn in a sample of metal-poor stars
• Observational Constraints on First-Star Nucleosynthesis. I. Evidence for Multiple Progenitors of CEMP-no Stars
• Spectroscopic Studies of Very Metal-Poor Stars with the Subaru High Dispersion Spectrograph. III. Light Neutron-Capture Elements
• From Nuclei to the Cosmos: Tracing Heavy-Element Production with the Oldest Stars
• Binarity in Carbon-Enhanced Metal-Poor stars
• High-Resolution Spectroscopy of Extremely Metal-Poor Stars from SDSS/SEGUE: I. Atmospheric Parameters and Chemical Compositions
• Building Late-Type Spiral Galaxies by In-Situ and Ex-Situ Star Formation
• Systematic non-LTE study of the $-2.6\le$ [Fe/H] $\le 0.2$ F and G dwarfs in the solar neighbourhood. II. Abundance patterns from Li to Eu
• The role of binaries in the enrichment of the early Galactic halo. III. Carbon-enhanced metal-poor stars -- CEMP-s stars
• Population Synthesis of Binary Carbon-enhanced Metal-poor Stars
• Global structure and kinematics of stellar haloes in cosmological hydrodynamic simulations
• Formation of In Situ Stellar Haloes in Milky Way-Mass Galaxies
• Carbon-Enhanced Metal-Poor Stars in the Inner and Outer Halo Components of the Milky Way
• Connecting the first galaxies with ultra faint dwarfs in the Local Group: chemical signatures of Population~III stars
• Stellar haloes of simulated Milky Way-like galaxies: Chemical and kinematic properties
• Deriving Stellar Effective Temperatures of Metal-Poor Stars with the Excitation Potential Method
• The Nucleosynthetic Imprint of 15-40 Solar Mass Primordial Supernovae on Metal-Poor Stars
• Stellar haloes in Milky-Way mass galaxies: From the inner to the outer haloes
• A Search for Nitrogen-Enhanced Metal-Poor Stars
• The Diverse Origins of Neutron-Capture Elements in the Metal-Poor Star HD 94028: Possible Detection of Products of i-process Nucleosynthesis
• Neutron-Capture Nucleosynthesis in the First Stars
• Spectroscopic analysis of metal-poor stars from LAMOST: early results
• The Origins of Two Classes of Carbon-Enhanced, Metal-Poor Stars
• Carbon-Enhanced Metal-Poor Stars: CEMP-s and CEMP-no Sub-Classes in the Halo System of the Milky Way
• Chemical Analysis of the Ninth Magnitude Carbon-Enhanced Metal-Poor Star BD+44 493
• The origin of nitrogen: Implications of recent measurements of N/O in Galactic metal-poor stars
• The formation of the Milky Way halo and its dwarf satellites, a NLTE-1D abundance analysis. I. Homogeneous set of atmospheric parameters
• Metal-Poor Stars Observed with the Magellan Telescope I. Constraints on Progenitor Mass and Metallicity of AGB Stars Undergoing s-Process Nucleosynthesis
• Carbon-enhanced metal-poor stars: a window on AGB nucleosynthesis and binary evolution. II. Statistical analysis of a sample of 67 CEMP-$s$ stars
• Disc Heating: Comparing the Milky Way with Cosmological Simulations
• Abundances of carbon-enhanced metal-poor stars as constraints on their formation
• Accuracy of atmospheric parameters of FGK dwarfs determined by spectrum fitting
• On the stellar halo metallicity profile of Milky Way-like galaxies in the Auriga simulations
• Hubble Space Telescope Near-Ultraviolet Spectroscopy of Bright CEMP-s Stars
• NLTE line formation for Mg\ione\ and Mg\ii\ in atmospheres of B-A-F-G-K stars
• The age structure of the Milky Way's halo
• The occurrence of nitrogen-enhanced metal-poor stars: implications for the initial mass function in the early Galactic halo
• G64-12 and G64-37 are Carbon-Enhanced Metal-Poor Stars
• Carbon abundances of the reference late-type stars from 1D analysis of atomic C I and molecular CH lines
• Non-LTE Sodium Abundance in Galactic Thick- and Thin-Disk Red Giants
• The central spheroids of Milky Way mass-sized galaxies
• Investigation of a sample of carbon-enhanced metal-poor stars observed with FORS and GMOS
• The Origin of the Milky Way's Halo Age Distribution
• High-resolution spectroscopic observations of the new CEMP-s star CD-50${}^{\circ }$776
• Carbon-enhanced metal-poor stars in the SDSS-APOGEE database
• The Puzzling Frequencies of CEMP and NEMP Stars

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