THE FIRST FLUORINE ABUNDANCE DETERMINATIONS IN EXTRAGALACTIC ASYMPTOTIC GIANT BRANCH CARBON STARS

• Published in: Astrophysical journal. Letters Vol. 737; no. 1; pp. L8 - jQuery1323916338333='48'
• Main Authors: Abia, C., Cunha, K., Cristallo, S., de Laverny, P., Domínguez, I., Recio-Blanco, A., Smith, V. V., Straniero, O.
• Format: Journal Article
• Language: English
• Published: United States Bristol : IOP Publishing 10.08.2011
• Subjects: ABUNDANCE; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON STARS; ELEMENT ABUNDANCE; ELEMENTS; FLUORINE; FLUORINE 19; FLUORINE ISOTOPES; GALAXIES; HALOGENS; ISOTOPES; LIGHT NUCLEI; MAGELLANIC CLOUDS; MAIN SEQUENCE STARS; NONMETALS; NUCLEI; ODD-EVEN NUCLEI; STABLE ISOTOPES; STARS
• ISSN: 2041-8205; 2041-8213
• DOI: 10.1088/2041-8205/737/1/L8

Fluorine (19F) abundances (or upper limits) are derived in six extragalactic asymptotic giant branch (AGB) carbon stars from the HF(1-0) R9 line at 2.3358 Delta *mm in high-resolution spectra. The stars belong to the Local Group galaxies, Large Magellanic Cloud, Small Magellanic Cloud, and Carina dwarf spheroidal, spanning more than a factor of 50 in metallicity. This is the first study to probe the behavior of F with metallicity in intrinsic extragalactic C-rich AGB stars. Fluorine could be measured only in four of the target stars, showing a wide range in F enhancements. Our F abundance measurements together with those recently derived in Galactic AGB carbon stars show a correlation with the observed carbon and s-element enhancements. The observed correlations, however, display a different dependence on the stellar metallicity with respect to theoretical predictions in low-mass, low-metallicity AGB models. We briefly discuss the possible reasons for this discrepancy. If our findings are confirmed in a larger number of metal-poor AGBs, the issue of F production in AGB stars will need to be revisited.