Carbon and helium abundances in Wolf-Rayet WC stars determined from optical recombination lines

Abstract

view Abstract Citations (49) References (33) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Carbon and Helium Abundances in Wolf-Rayet WC Stars Determined from Optical Recombination Lines Torres, Ana V. Abstract Carbon to helium ratios and ionization fractions are derived for 74 WC stars in the Galaxy and the LMC from optically thin recombination lines at visual wavelengths. The range of C/He ratios is 0.13 to 0.79 by number, similar to the ratios calculated by Nugis and ~20 times greater than the ratios of Smith and Willis. These ratios also agree with the abundances determined in the most recent evolutionary models of massive stars, which include mass loss, convective dredge-up, and new nuclear reaction rates. The range of values found for the C/He ratios implies that the convective cores of WC stars do not occupy a very large mass fraction. The C/He ratio differs within a subtype by a factor of 3 or less, but the mean tends to increase toward earlier subtypes, although the standard deviation from the mean is large enough to allow the interpre- tation that the C/He ratio is constant for all WC subtypes. Publication: The Astrophysical Journal Pub Date: February 1988 DOI: 10.1086/166046 Bibcode: 1988ApJ...325..759T Keywords: Abundance; Carbon; Helium; Stellar Spectra; Wolf-Rayet Stars; Line Spectra; Magellanic Clouds; Recombination Coefficient; Astrophysics; GALAXIES: MAGELLANIC CLOUDS; STARS: ABUNDANCES; STARS: WOLF-RAYET full text sources ADS | data products SIMBAD (73) NED (1)