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Oxygen Abundances in LI-Depleted F-Type Stars

Published online by Cambridge University Press:  12 April 2016

Ramon J. Garcia Lopez ,
Rafael Rebolo ,
Artemio Herrero  and
John E. Beckman
Ramon J. Garcia Lopez
Affiliation:
Instituto de Astrofísica de Canarias, E-38200, La Laguna, Tenerife, Spain
Rafael Rebolo
Affiliation:
Instituto de Astrofísica de Canarias, E-38200, La Laguna, Tenerife, Spain
Artemio Herrero
Affiliation:
Instituto de Astrofísica de Canarias, E-38200, La Laguna, Tenerife, Spain
John E. Beckman
Affiliation:
Instituto de Astrofísica de Canarias, E-38200, La Laguna, Tenerife, Spain

Abstract

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We have obtained the oxygen abundance in a sample of 44 F-type dwarfs in the Ursa Major group and the Hyades open cluster, using an NLTE analysis of the O I infrared triplet at λλ 7771-7775 Å. These clusters show the “lithium gap” in the F spectral range, and it has been suggested that if this phenomenon were due to microscopic diffusion, their Li-depleted stars could also show oxygen and/or nitrogen depletion. Our results here show a substantial measure of uniformity in the oxygen abundances. The data might indicate a very small dip (< 0.1 dex) in the O abundance for stars located in the Li gap. Microscopic diffusion seems to be the only known mechanism able to produce an oxygen dip. If this mechanism were responsible for the Li gap, it would have to account for a depletion of up to two orders of magnitude in Li and, at the same time, less than 0.1 dex in oxygen. We note that turbulent mixing could modify a microscopic diffusion pattern in order to yield the observed abundances of the two elements.

Type
II. Atmospheres, a window to the interior
Information
International Astronomical Union Colloquium , Volume 137: Inside the Stars , 1993 , pp. 187 - 189
Copyright
Copyright © Astronomical Society of the Pacific 1993

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