The Origin of Fluorine: Abundances in AGB Carbon Stars Revisited

Abstract

Revised spectroscopic parameters for the HF molecule and a new CN line list in the 2.3 mu region have been recently available, allowing a revision of the F content in AGB stars. AGB carbon stars are the only observationally confirmed sources of fluorine. Nowadays there is not a consensus on the relevance of AGB stars in its Galactic chemical evolution. The aim of this article is to better constrain the contribution of these stars with a more accurate estimate of their fluorine abundances. Using new spectroscopic tools and LTE spectral synthesis, we redetermine fluorine abundances from several HF lines in the K-band in a sample of Galactic and extragalactic AGB carbon stars of spectral types N, J and SC spanning a wide range of metallicities. On average, the new derived fluorine abundances are systematically lower by 0.33 dex with respect to previous determinations. This may derive from a combination of the lower excitation energies of the HF lines and the larger macroturbulence parameters used here as well as from the new adopted CN line list. Yet, theoretical nucleosynthesis models in AGB stars agree with the new fluorine determinations at solar metallicities. At low metallicities, an agreement between theory and observations can be found by handling in a different way the radiative/convective interface at the base of the convective envelope. New fluorine spectroscopic measurements agree with theoretical models at low and at solar metallicity. Despite this, complementary sources are needed to explain its observed abundance in the solar neighbourhood.

9 pages, 4 figures, accepted in A&A

References in corpus (15)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Evolution and nucleosynthesis of asymptotic giant branch stellar models of low metallicity
• Correlated Strontium and Barium Isotopic Compositions of Acid-Cleaned Single Silicon Carbides from Murchison
• On the need of the Light Elements Primary Process (LEPP)
• Cool luminous stars: the hybrid nature of their infrared spectra -- Carbon, oxygen, and their isotopic abundances in 23 K - M giant stars
• s-Processing in AGB Stars Revisited. I. Does the Main Component Constrain the Neutron Source in the 13C-Pocket?
• The 13C-Pocket Structure in AGB Models: Constraints from Zirconium Isotope Abundances in Single Mainstream SiC Grains
• Abundances in bulge stars from high-resolution, near-IR spectra I. The CNO elements observed during the science verification of CRIRES at VLT
• Effects of nuclear cross sections on ${}^{19}$F nucleosynthesis at low metallicities
• The Chemical Evolution of Fluorine in the Bulge - High-resolution K-band spectra of giants in three fields
• A new solar fluorine abundance and a fluorine determination in the two open clusters M 67 and NGC 6404
• Fluorine in the solar neighborhood - is it all produced in AGB-stars?
• Detection of Fluorine in the Halo Planetary Nebula BoBn 1: Evidence For a Binary Progenitor Star
• Fluorine Abundances of Galactic Low-Metallicity Giants
• Revisited fluorine abundances in the globular cluster M22 (NGC 6656)

Cited by in corpus (31)

• Chemical evolution with rotating massive star yields: I. The solar neighbourhood and the s-process elements
• Chemical equilibrium in AGB atmospheres: Successes, failures, and prospects for small molecules, clusters, and condensates
• Non standard s-process in massive rotating stars. Yields of $10-150$ $M_{\odot }$ models at $Z=10^{-3}$
• Physical conditions in the central molecular zone inferred by H3+
• $s$-Processing in AGB Stars Revisited. II. Enhanced ${}^{13}$C Production Through MHD-Induced Mixing
• s-Processing in AGB Stars Revisited. III. Neutron captures from MHD mixing at different metallicities and observational constraints
• When binaries keep track of recent nucleosynthesis: The Zr - Nb pair in extrinsic stars as an s-process diagnostic
• Presolar grain isotopic ratios as constraints to nuclear and stellar parameters of AGB nucleosynthesis
• Fluorine in the Solar neighborhood: No evidence for the neutrino process
• Magnetic-buoyancy-induced mixing in AGB Stars: fluorine nucleosynthesis at different metallicities
• The puzzle of the CNO isotope ratios in AGB carbon stars
• Properties of carbon stars in the Solar neighbourhood based on Gaia DR2 astrometry
• Fluorine in the solar neighborhood: modelling the Galactic thick and thin discs
• Fluorine in the solar neighbourhood: the need for several cosmic sources
• Solar System Abundances and Condensation Temperatures of the Halogens Fluorine, Chlorine, Bromine, and Iodine
• Constraining $\nu$-Process Production of Fluorine through Cosmic Ray Nucleosynthesis
• ATOMIUM: Halide molecules around the S-type AGB star W Aquilae
• New Multielement Isotopic Compositions of Presolar SiC Grains: Implications for Their Stellar Origins
• Fluorine Abundances in the Galactic Disk
• Chemical Abundances Of Open Clusters From High-Resolution Infrared Spectra. I. NGC 6940
• Chemical Evolution of Fluorine in the Milky Way
• Fluorine Abundances in the Galactic Nuclear Star Cluster
• M Giants with IGRINS II. Chemical Evolution of Fluorine at High Metallicities
• First detection of AlF line emission towards M-type AGB stars
• The carbon star DY Persei may be a cool R Coronae Borealis variable
• Physical properties of the fluorine and neutron-capture element-rich PN Jonckheere 900
• Etching glass in the early Universe: Luminous HF and water emission in a QSO-SMG pair at z=4.7
• Nucleosynthetic yields of intermediate-mass primordial to extremely metal-poor stars
• Extended view on the dust shells around two carbon stars
• Fluorine Abundances in Local Stellar Populations
• Stellar yields and abundances: new directions from planetary nebulae