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UV- And Visual Spectroscopy of Nine Extremely Helium Rich Subluminous-O-Stars

Published online by Cambridge University Press:  12 April 2016

U. Heber ,
J.S. Drilling  and
D. Husfeld
U. Heber
Affiliation:
Institut f. theor. Physik u. Sternwarte, Kiel, F.R.G.
J.S. Drilling
Affiliation:
Louisiana State University, Baton Rouge, USA
D. Husfeld
Affiliation:
Universitätssternwarte München, F.R.G.

Abstract

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Nine helium rich sdO stars are found to show no trace of hydrogen on high resolution visual spectra. Effective temperatures derived from UV fluxes range from 42500 K to 80000 K. A dichotomy with respect to the C/N ratio is found which is reminiscent of the OBN and OBC stars near the main sequence. It is estimated that about 20% of the sdO stars are extremely helium rich. This fraction compares nicely with those of the (helium rich) DB white dwarfs (20%) and the helium rich central stars of planetary nebulae (less than 35%).

Type
VII Related Objects
Information
International Astronomical Union Colloquium , Volume 87: Hydrogen Deficient Stars and Related Objects , 1985 , pp. 345 - 351
Copyright
Copyright © Reidel 1986

References

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