Fluorine in carbon-enhanced metal-poor stars: a binary scenario

Abstract

A super-solar fluorine abundance was observed in the carbon-enhanced metal-poor (CEMP) star HE 1305+0132 ([F/Fe] = +2.90, [Fe/H] = -2.5). We propose that this observation can be explained using a binary model that involve mass transfer from an asymptotic giant branch (AGB) star companion and, based on this model, we predict F abundances in CEMP stars in general. We discuss wether F can be used to discriminate between the formation histories of most CEMP stars: via binary mass transfer or from the ejecta of fast-rotating massive stars. We compute AGB yields using different stellar evolution and nucleosynthesis codes to evaluate stellar model uncertainties. We use a simple dilution model to determine the factor by which the AGB yields should be diluted to match the abundances observed in HE 1305+0132. We further employ a binary population synthesis tool to estimate the probability of F-rich CEMP stars. The abundances observed in HE 1305+0132 can be explained if this star accreted 3-11% of the mass lost by its former AGB companion. The primary AGB star should have dredged-up at least 0.2 Msun of material from its He-rich region into the convective envelope via third dredge-up, which corresponds to AGB models of Z ~ 0.0001 and mass ~ 2 Msun. Many AGB model uncertainties, such as the treatment of convective borders and mass loss, require further investigation. We find that in the binary scenario most CEMP stars should also be FEMP stars, that is, have [F/Fe] > +1, while fast-rotating massive stars do not appear to produce fluorine. We conclude that fluorine is a signature of low-mass AGB pollution in CEMP stars, together with elements associated with the slow neutron-capture process.

accepted for publication on A&A Letters

References in corpus (24)

• Approximate input physics for stellar modelling
• Carbon Enhanced Metal-Poor Stars. I. Chemical Compositions of 26 Stars
• The early star generations: the dominant effect of rotation on the CNO yields
• The Binary Frequency Among Carbon-Enhanced, s-Process Rich, Metal-Poor Stars
• Thermohaline mixing: A physical mechanism governing the photospheric composition of low-mass giants
• Stellar Models and Yields of Asymptotic Giant Branch Stars
• Variations in the Abundance Pattern of Extremely Metal-poor Stars and Nucleosynthesis in Population III Supernovae
• s Process in low-mass Asymptotic Giant Branch Stars
• Reaction Rates Uncertainties and the Production of F19 in AGB Stars
• The Frequency of Carbon-Enhanced Metal-Poor Stars in the Galaxy from the HERES sample
• Asymptotic Giant Branch evolution at varying surface C/O ratio: effects of changes in molecular opacities
• Carbon-Enhanced Metal-Poor Stars. III. Main-Sequence Turn-Off Stars from the SDSS/SEGUE Sample
• Wind accretion in binary stars II. Accretion rates
• CS22964-161: A Double-Lined Carbon- and s-Process-Enhanced Metal-Poor Binary Star
• Near-UV Observations of CS29497-030: New Constraints on Neutron-Capture Nucleosynthesis Processes
• The Frequency of Carbon Stars Among Extremely Metal-Poor Stars
• Molecular opacities for low-mass metal-poor AGB stars undergoing the Third Dredge Up
• Wind accretion in binary stars - I. Mass accretion ratio
• The thermonuclear production of F19 by Wolf-Rayet stars revisited
• CH stars at High Galactic Latitudes
• Fluorine abundances in planetary nebulae
• Evolution and nucleosynthesis of primordial low mass stars
• The impact of the 18F(a,p)21Ne reaction on asymptotic giant branch nucleosynthesis
• The thermonuclear rate for the 19F(a,p)22Ne reaction at stellar temperatures

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• The Evolution of Isotope Ratios in the Milky Way Galaxy
• The s process in asymptotic giant branch stars of low metallicity and the composition of carbon-enhanced metal-poor stars
• Evolution and Nucleosynthesis of Extremely Metal Poor & Metal-Free Low- and Intermediate-Mass Stars I: Stellar Yield Tables and the CEMPs
• Population Synthesis of Binary Carbon-enhanced Metal-poor Stars
• JINAbase: A database for chemical abundances of metal-poor stars
• s-Process in Low Metallicity Stars. I. Theoretical Predictions
• s-Process in Low Metallicity Stars. III. Individual analysis of CEMP-s and CEMP-s/r with AGB models
• Fluorine and Sodium in C-rich low-metallicity stars
• Non standard s-process in massive rotating stars. Yields of $10-150$ $M_{\odot }$ models at $Z=10^{-3}$
• Evolution of Fluorine Abundances with the ν-Process
• Metal-Poor Stars Observed with the Magellan Telescope I. Constraints on Progenitor Mass and Metallicity of AGB Stars Undergoing s-Process Nucleosynthesis
• Chemical abundances in giants stars of the tidally disrupted globular cluster NGC 6712 from high-resolution infrared spectroscopy
• The Origin and Evolution of the Halo PN BoBn 1: From a Viewpoint of Chemical Abundances Based on Multiwavelength Spectra
• Nucleosynthesis of binary-stripped stars
• The origin of low [alpha/Fe] ratios in extremely metal-poor stars
• Light element abundances in carbon-enhanced metal-poor stars
• Detection of Fluorine in the Halo Planetary Nebula BoBn 1: Evidence For a Binary Progenitor Star
• Constraining Nucleosynthesis in Two CEMP Progenitors Using Fluorine
• Etching glass in the early Universe: Luminous HF and water emission in a QSO-SMG pair at z=4.7
• Mass transfer of low-mass binaries and chemical anomalies among unevolved stars in globular clusters
• The fractions of post-binary-interaction stars and evolved blue straggler stars on the red giant branch of globular clusters
• The impact of the 18F(a,p)21Ne reaction on fluorine production in AGB stars