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arXiv · 1407.2157

Carbon and Oxygen abundances across the Hertzsprung gap

Jens Adamczak·David L. Lambert
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Abstract

We derived atmospheric parameters and spectroscopic abundances for C and O for a large sample of stars located in the Hertzsprung gap in the Hertzsprung-Russell Diagram in order to detect chemical peculiarities and get a comprehensive overview of the population of stars in this evolutionary state. We have observed and analyzed high resolution spectra (R = 60 000) of 188 stars in the mass range 2 - 5 Msun with the 2.7 m Harlan J. Smith Telescope at the McDonald Observatory including 28 stars previously identified as Am/Ap stars. We find that the C and O abundances of the majority of stars in the Hertzsprung gap are in accordance with abundances derived for local lower mass dwarfs but detect expected peculiarities for the Am/Ap stars. The C and O abundances of stars with Teff < 6500 K are slightly lower than for the hotter objects but the C/O ratio is constant in the analyzed temperature domain. No indication of an alteration of the C and O abundances of the stars by mixing during the evolution across the Hertzsprung gap could be found before the homogenization of their atmospheres by the first dredge-up.

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Jens Adamczak, David L. Lambert. 2014-07-08. Carbon and Oxygen abundances across the Hertzsprung gap. https://doi.org/10.1088/0004-637x/791/1/58

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