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arXiv · 1908.04587

Heavy-metal enrichment in the intermediate He-sdOB pulsator Feige 46

Marilyn Latour·Matti Dorsch·Ulrich Heber
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Abstract

The intermediate He-enriched hot subdwarf star Feige 46 was recently reported as the second member of the V366 Aqr (or He-sdOBV) pulsating class. Feige 46 is very similar to the prototype of the class, LS IV$-$14116, not only in terms of pulsational properties, but also in terms of atmospheric parameters and kinematic properties. LS IV$-$14116 is additionally characterized by a very peculiar chemical composition, with extreme overabundances of the trans-iron elements Ge, Sr, Y, and Zr. In this paper, we investigate the possibility that the similitude between both pulsators extends to their chemical composition. We retrieved archived optical and UV spectroscopic observations of Feige 46 and perform an abundance analysis using model atmospheres and synthetic spectra computed with TLUSTY and SYNSPEC. In total, we derive abundances for 16 metallic elements and provide upper limits for four additional elements. From absorption lines in the optical spectrum of the star we measure an enrichment of more than 10 000$\times$ solar for yttrium and zirconium. As for strontium, the UV spectrum revealed it to be equally enriched. Our results confirm that Feige 46 is not only a member of the now growing group of "heavy-metal" subdwarfs, but also has an abundance pattern remarkably similar to that of LS IV$-$14116.

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Marilyn Latour, Matti Dorsch, Ulrich Heber. 2019-08-13. Heavy-metal enrichment in the intermediate He-sdOB pulsator Feige 46. https://doi.org/10.1051/0004-6361/201936247

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