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Overabundance of Sodium in the Atmospheres of Massive Supergiants as a Possible Manifestation of Nena Cycle

Published online by Cambridge University Press:  12 April 2016

A.A. Boyarchuk ,
P.A. Denisenkov ,
I. Hubený ,
V.V. Ivanov ,
I. Kubát ,
L.S. Lyubimkov  and
N.A. Sakhibullin
A.A. Boyarchuk
Affiliation:
– Crimean Astrophysical Observatory, USSR
P.A. Denisenkov
Affiliation:
–Leningrad University, USSR
I. Hubený
Affiliation:
–Astronomical Institute, CSSR
V.V. Ivanov
Affiliation:
–Leningrad University, USSR
I. Kubát
Affiliation:
–Astronomical Institute, CSSR
L.S. Lyubimkov
Affiliation:
– Crimean Astrophysical Observatory, USSR
N.A. Sakhibullin
Affiliation:
–Kazan’ University, USSR

Extract

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Studies of chemical composition of the atmospheres of F-K supergiants have revealed the existence of two specific peculiarities, deficit of carbon and excess of nitrogen. Anomalous abundances of C and N in yellow supergiants is explained by mixing of surface material with CNO-processed material of stellar interiors (the first dredge-up). Somewhat unexpectedly, F-K supergiants were found to show one more general chemical peculiarity: overabundance of sodium. Fig.1 shows the available values of [Na/H]=log[N(Na)/N(H)]*−log[N(Na)/N(H)]⊙ as summarized by Boyarchuk and Lyubimkov( 1983). Different symbols refer to data of various authors. Fig.1 shows that sodium overabundance increases with the decrease of surface gravity. For small log g it reaches [Na/H] ~ ~ 1. Recently Sasselov(1986) has suggested that this correlation is essentially a consequence of a relation between [Na/H] and a mass of supergiant.

Type
Part I. Chemical Peculiarities as Probe of Stellar Evolution
Information
International Astronomical Union Colloquium , Volume 108: Atmospherics Diagnostics of Stellar Evolution: Chemical Peculiarity, Mass Loss, and Explosion , 1988 , pp. 94 - 96
Copyright
Copyright © Springer-Verlag 1988

References

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