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2000MNRAS.315..407D - Mon. Not. R. Astron. Soc., 315, 407-422 (2000/June-3)
Quantitative analysis of WC stars: constraints on neon abundances from ISO-SWS spectroscopy.
DESSART L., CROWTHER P.A., HILLIER D.J., WILLIS A.J., MORRIS P.W. and VAN DER HUCHT K.A.
Abstract (from CDS):
ISO-SWS data sets reveal the [Neiii] 15.5-µm line in each of our targets, while [Neii] 12.8µm, [Siv] 10.5µm and [Siii] 18.7µm are observed solely in γ2Vel. Using a method updated from Barlow et al. to account for clumped winds, we derive Ne/He=(3-4)x10–3 by number, plus S/He=6x10–5 for γ2Vel. Neon is highly enriched, such that Ne/S in γ2Vel is eight times higher than cosmic values. However, observed Ne/He ratios are a factor of 2 lower than predictions of current evolutionary models of massive stars. An imprecise mass loss and distance were responsible for the much greater discrepancy in neon content identified by Barlow et al.
Our sample of WC5-8 stars span a narrow range in T∗ (=55-71kK), with no trend towards higher temperature at earlier spectral type, supporting earlier results for a larger sample by Koesterke & Hamann. Stellar luminosities range from 100000 to 500000L☉, while {formmu1} adopting clumped winds, in which volume filling factors are 10per cent. In all cases, wind performance numbers are less than 10, significantly lower than recent estimates. Carbon abundances span 0.08≤C/He≤0.25 by number, while oxygen abundances remain poorly constrained.
Abstract Copyright: 2000, Royal Astronomical Society
Journal keyword(s): stars: abundances - stars: evolution - stars: fundamental parameters - stars: Wolf-Rayet - infrared: stars
Simbad objects: 14
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