Are C-rich ultra iron-poor stars also He-rich?
نویسندگان
چکیده
منابع مشابه
Properties 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 کاملThe Frequency of C-Rich Extremely Metal Poor Stars
We demonstrate that there are systematic scale errors in the [Fe/H] values determined by the Hamburg/ESO Survey (and by the HK Survey by inference) for certain extremely metal poor (EMP) highly C-enhanced giants. The consequences of these scale errors are that a) the fraction of carbon stars at extremely low metallicities has been substantially overestimated in several papers in the recent lite...
متن کاملEvolution of the First Stars: CNO Yields and the C-rich Extremely Metal Poor Stars
Rotating massive stars at Z = 10 and 10 lose a great part of their initial mass through stellar winds. The chemical composition of the rotationally enhanced winds of very low Z stars is very peculiar. The winds show large CNO enhancements by factors of 10 to 10, together with large excesses of C and O and moderate amounts of Na and Al. The excesses of primary N are particularly striking. When t...
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: Astronomy and Astrophysics
سال: 2010
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361/200913377