منابع مشابه
O(he) Stars
Spectral analyses of H-deficient post-AGB stars have shown that a small group of four extremely hot objects exists which have almost pure He absorption-line spectra in the optical. These are classified as O(He) stars. For their evolution there are two scenarios: They could be the long-sought hot successors of RCrB stars, which have not been identified up to now. If this turns out to be true, th...
متن کاملProperties of He - rich stars
We present an abundance analysis of light elements in the most massive chemically peculiar (CP) stars, He-rich stars. The analysis is based on both low and high-resolution observations collected at ESO, La Silla, Chile in the optical region and includes 6 standard and 21 He-rich stars. Light element abundances display a diverse pattern from under-solar up to above-solar values. Carbon is found ...
متن کاملASTROPHYSICS Properties of He - rich stars
We present a study of helium rich atmospheres in the interval He/H 0.1–1.0 as derived from fully consistent model computations for effective temperature (from 15000K up to 32000K) and surface gravity (log g=3.5 and 4.0). Also the basic diagnostic tools are re-examined, particularly, broad-band UBV and intermediate photometric systems, hydrogen line profiles, continuum fluxes and helium equivale...
متن کاملDiscovery of magnetic fields in three He variable Bp stars with He and Si spots
stars: magnetic fields It is essential for the understanding of stellar structure models of high mass stars to explain why constant stars, non-pulsating chemically peculiar hot Bp stars and pulsating stars co-exist in the slowly pulsating B stars and β Cephei instability strips. We have conducted a search for magnetic fields in the four Bp stars HD 55522, HD 105382, HD 131120, and HD 138769 whi...
متن کاملASTRONOMY AND ASTROPHYSICS Properties of He - rich stars I . Their
A determination of the surface gravity and an abundance analysis of helium in a sample of 17He-rich and 5 normal, reference stars is presented. These results are derived from low resolution CCD spectra, but each star was measured at least 6 times in order to obtain a significant average spectrum for the spectroscopic variables. The helium abundances derived from the models used are very close t...
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ژورنال
عنوان ژورنال: International Astronomical Union Colloquium
سال: 1993
ISSN: 0252-9211
DOI: 10.1017/s0252921100020790