Stellar Archaeology: a Keck Pilot Program on Extremely Metal- Poor Stars From the Hamburg/ESO Survey. III. The Lead (Pb) Star HE 0024-2523

Abstract

We present a detailed abundance analysis, including spectral syntheses, of a very metal-poor ([Fe/H]= -2.7), peculiar main sequence star, HE0024-2523 detected during the course of the Keck Pilot Program. Radial velocities of this star were obtained during four different observing runs over a time span of 1.1 years, and demonstrate that it is clearly a short period spectroscopic binary. An orbital solution was obtained, and orbital parameters were determined with high precision. The rotational velocity was also measured (vsin i=9.7$\pm$1.5 kms); rotation appears likely to be synchronous with the orbit. The abundance analysis and spectral syntheses indicate that the object is a CH star characterized by extreme s-process enrichment, likely due to mass accretion from an evolved companion which has now probably become a white dwarf. The lead (Pb) abundance of HE0024-2523 is very high, the same as that of the recently discovered lead-rich metal-poor star CS 29526-110, [Pb/Fe]=+3.3. The abundance ratio of the heavy-s to light-s elements, as characterized by Pb and Ba, [Pb/Ba]=+1.9, is the highest yet found for any metal-poor star, and is about 0.7 dex higher than that of CS29526-110. On the basis of the measured isotopic ratio of carbon (12C/13C about 6) we argue that the mass donor must have had an original mass of at least 3 Msun. The unusually short period of this CH star suggests that it underwent a past common-envelope phase with its evolved companion. Our results are compared to the latest available models for AGB yields and s-process nucleosynthesis. We also discuss the possible connection between HE0024-2523 the lithium depletion of halo stars, and halo blue straggler formation.

55 pages, 17 color figures included; Accepted for publication in the February 2003 issue of the Astronomical Journal

References in corpus (20)

• Towards Better Age Estimates for Stellar Populations: The Y^2 Isochrones for Solar Mixture
• A standard stellar library for evolutionary synthesis: II. The M dwarf extension
• The extreme r-element rich, iron-poor halo giant CS31082-001: Implications for the r-process site(s) and radioactive cosmochronology
• Nucleosynthesis and mixing on the Asymptotic Giant Branch. III. Predicted and observed s-process abundances
• Measurement of stellar age from uranium decay
• Stellar Iron Abundances: non-LTE Effects
• Evidence of Multiple r-Process Sites in the Early Galaxy: New Observations of CS 22892-052
• Double Core Evolution X. Through the Envelope Ejection Phase
• Neutron Capture Elements in s-Process-Rich, Very Metal-Poor Stars
• The stellar content of the Hamburg/ESO survey. II. A large, homogeneously-selected sample of high latitude carbon stars
• The Chemical Composition of Carbon-Rich, Very Metal-Poor Stars: A New Class of Mildly Carbon-Rich Objects Without Excess of Neutron-Capture Elements
• Structure, Evolution and Nucleosynthesis of Primordial Stars
• Stellar Archaeology: a Keck Pilot Program on Extremely Metal-Poor Stars from the Hamburg/ESO Survey. II. Abundance Analysis
• The stellar content of the Hamburg/ESO survey. I. Automated selection of DA white dwarfs
• Detection of Lead in the Carbon-Rich, Very Metal-Poor Star LP625-44: A Strong Constraint on s-Process Nucleosynthesis at Low Metallicity
• Nucleosynthesis of s-elements in zero-metal AGB stars
• Ultra-Lithium-Deficient Halo Stars and Blue Stragglers: A Common Origin?
• Chemical composition of carbon-rich, very metal-poor subgiant LP625-44 observed with the Subaru/HDS
• Rapid rotation of ultra-Li-depleted halo stars and their association with blue stragglers
• Stellar Archaeology: a Keck Pilot Program on Extremely Metal-Poor Stars From the Hamburg/ESO Survey. I Stellar Parameters

Cited by in corpus (92)

• The s Process: Nuclear Physics, Stellar Models, Observations
• Carbon Enhanced Metal-Poor Stars. I. Chemical Compositions of 26 Stars
• Chemical evolution with rotating massive star yields: I. The solar neighbourhood and the s-process elements
• The Binary Frequency Among Carbon-Enhanced, s-Process Rich, Metal-Poor Stars
• The first chemical enrichment in the universe and the formation of hyper metal-poor stars
• The s-Process in Low Metallicity Stars. II. Interpretation of High-Resolution Spectroscopic Observations with AGB models
• Short-lived Nuclei in the Early Solar System: Possible AGB Sources
• HE0107-5240, A Chemically Ancient Star.I. A Detailed Abundance Analysis
• Is HE0107-5240 A Primordial Star? -- The Characteristics of Extremely Metal-Poor Carbon-Rich Stars --
• The Frequency of Carbon-Enhanced Metal-Poor Stars in the Galaxy from the HERES sample
• Normal and Outlying Populations of the Milky Way Stellar Halo at [Fe/H] < -2
• The stellar content of the Hamburg/ESO survey. IV. Selection of candidate metal-poor stars
• Chemistry of the Sagittarius Dwarf Galaxy: a Top-Light IMF, Outflows and the R-Process
• Binarity in Carbon-Enhanced Metal-Poor stars
• Abundances of C, N, O in slightly evolved stars in the globular clusters NGC 6397, NGC 6752 and 47 Tuc
• Abundances In Very Metal Poor Dwarf Stars
• The role of binaries in the enrichment of the early Galactic halo. III. Carbon-enhanced metal-poor stars -- CEMP-s stars
• The Hamburg/ESO R-process Enhanced Star survey (HERES) III. HE 0338-3945 and the formation of the r+s stars
• JINAbase: A database for chemical abundances of metal-poor stars
• Stellar Archaeology -- Exploring the Universe with Metal-Poor Stars
• Carbon-Enhanced Metal-Poor Stars. III. Main-Sequence Turn-Off Stars from the SDSS/SEGUE Sample
• Abundance Analysis of HE2148-1247, A Star With Extremely Enhanced Neutron Capture Elements
• s-Process in Low Metallicity Stars. III. Individual analysis of CEMP-s and CEMP-s/r with AGB models
• The Origin of Carbon-Enhancement and Initial Mass Function of Extremely Metal-Poor Stars in the Galactic Halo
• The End of Nucleosynthesis: Production of Lead and Thorium in the Early Galaxy
• Carbon Stars in the Hamburg/ESO Survey: Abundances
• The Stellar Abundances for Galactic Archaeology (SAGA) Database II - Implications for Mixing and Nucleosynthesis in Extremely Metal-Poor Stars and Chemical Enrichment of the Galaxy
• First stars X. The nature of three unevolved Carbon-Enhanced Metal-Poor stars
• First stars IV.CS 29497-030: Evidence for operation of the s-process at very low metallicity
• Analysis of the carbon-rich very metal-poor dwarf G77-61
• Binary properties of CH and Carbon-Enhanced Metal-Poor stars
• CS 30322-023: an ultra metal-poor TP-AGB star?
• New analysis of the two carbon-rich stars CS 22948-27 and CS 29497-34 : binarity and neutron-capture elements
• Exploring the Origin of Lithium, Carbon, Strontium and Barium with four new Ultra Metal-Poor Stars
• Dredge-up and envelope burning in intermediate mass giants of very low metallicity
• A Search for Nitrogen-Enhanced Metal-Poor Stars
• Fluorine and Sodium in C-rich low-metallicity stars
• Elemental abundances and classification of CEMP stars
• The Frequency of Carbon Stars Among Extremely Metal-Poor Stars
• Principal Component Analysis on Chemical Abundances Spaces
• Stellar Sources for Heavy r-Process Nuclei
• The s-process in metal-poor stars: Abundances for 22 neutron-capture elements in CS 31062-050
• Detailed Abundances of Two Very Metal-Poor Stars in Dwarf Galaxies
• The Origins of Two Classes of Carbon-Enhanced, Metal-Poor Stars
• Low-mass supernovae in the early Galactic halo: source of the double r/s-process enriched halo stars?
• Chemical abundances and kinematics of barium stars
• TOPoS: IV. Chemical abundances from high-resolution observations of seven EMP stars
• The Pristine Survey IV: Approaching the Galactic metallicity floor with the discovery of an ultra metal-poor star
• Metal-Poor Stars Observed with the Magellan Telescope I. Constraints on Progenitor Mass and Metallicity of AGB Stars Undergoing s-Process Nucleosynthesis
• Lithium abundances in CEMP stars
• Carbon-enhanced metal-poor stars: a window on AGB nucleosynthesis and binary evolution. I. Detailed analysis of 15 binary stars with known orbital periods
• Estimation of Carbon Abundances in Metal-Poor Stars. I. Application to the "Strong G-band" stars of Beers, Preston, & Shectman
• Carbon and Strontium Abundances of Metal-Poor Stars
• The effects of thermohaline mixing on low-metallicity asymptotic giant branch stars
• The Hobby-Eberly Telescope "Chemical Abundances of Stars in the Halo" (CASH) Project. I. The Lithium-, s-, and r-Enhanced Metal-Poor Giant HKII 17435-00532
• Modelling the observed properties of carbon-enhanced metal-poor stars using binary population synthesis
• Binary Blue Metal-Poor Stars: Evidence for AGB Mass Transfer
• Chemical Abundance Signature of J0023+0307 -- A Second-Generation Main-Sequence Star with [Fe/H]<-6
• Spectroscopic Studies of Extremely Metal-Poor Stars with Subaru/HDS:I. Observational Data
• Giants reveal what dwarfs conceal: Li abundance in lower RGB stars as diagnostic of the primordial Li
• Rubidium and lead abundances in giant stars of the globular clusters M 13 and NGC 6752
• To Ba or not to Ba: Enrichment in s-process elements in binary systems with WD companions of various masses
• Chemical Abundances for Evolved Stars in M5: Lithium through Thorium
• The subgiant branch of omega Cen seen through high-resolution spectroscopy. I. The first stellar generation in omega Centauri?
• Chemical abundances and kinematics of a sample of metal-rich barium stars
• Spectroscopic study of CEMP-(s & r/s) stars- Revisiting classification criteria and formation scenarios, highlighting i-process nucleosynthesis
• The 139La(n,gamma) cross section: key for the onset of the s process
• CD-62\degree1346: an extreme halo or hypervelocity CH~star?
• Lithium in CEMP-no stars: A new constraint on the lithium depletion mechanism in the early universe
• Subaru/HDS study of CH stars: elemental abundances for stellar neutron-capture process studies
• Jurassic: A Chemically Anomalous Structure in the Galactic Halo
• Enrichment of Strontium in Dwarf Galaxies
• Oxygen and light element synthesis by neutron-capture reactions in metal-free and extremely metal-poor AGB stars
• Investigation of a sample of carbon-enhanced metal-poor stars observed with FORS and GMOS
• The origin of the lead-rich stars in Galactic halo: investigation of the model parameters for the s-process
• Carbon Abundances of Three Carbon-Enhanced Metal-Poor Stars from High-Resolution Gemini-S/bHROS Spectra of the 8727A [C I] Line
• Chemical analysis of two extremely metal-poor stars HE 2148-2039 and HE 2155-2043
• Abundances of neutron-capture elements in G 24-25. A halo-population CH subgiant
• Carbon-enhanced stars with short orbital and spin periods
• The Binary Dwarf Carbon Star SDSS J125017.90+252427.6
• Detailed abundances in a sample of very metal poor stars
• A Few Binary Star Puzzles for Roberto on the Occasion of His Birthday
• Europium enrichment and hierarchical formation of the Galactic halo
• High-resolution spectroscopic observations of the new CEMP-s star CD-50${}^{\circ }$776
• The s-process enriched star HD 55496: origin from a globular cluster or from the tidal disruption of a dwarf galaxy?
• Accretion of chemically fractionated material on a wide binary with a blue straggler
• The study of s-process nucleosynthesis based on barium stars, CEMP-s and CEMP-r/s stars
• Optical and NIR spectroscopy of cool CEMP stars to probe the nucleosynthesis in low mass AGB binary system
• Investigation of the single neutron exposure model for the s-process: the primary nature of the neutron source
• Study of the abundance features of the metal-poor star HD 94028
• The true nature of HE0057-5959, the most metal-poor Li-rich star
• LAMOST J045019.27+394758.7, with peculiar abundances of N, Na, V, Zn, is possibly a Sculptor dwarf galaxy escapee