2010/01/25 by C. S. Jeffery W.-R. Hamann, C. S. Jeffery W. -R. Hamann, Hamann, C. S. Jeffery W. -R. · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #FOS: Physical sciences #Gamma-ray bursts and supernovae #Solar and Stellar Astrophysics (astro-ph.SR) #Stellar, planetary, and galactic studies #astro-ph.SR
paper · pdf · doi:10.48550/arxiv.1001.4399
13 pages, 11 figures, 4 tables, plus 5 pages, 5 figures online only. MNRAS, in press
arxiv created 2010/01/25 · openalex publication_date 2010/01/25 · arxiv updated 2010/02/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Extreme helium stars are very rare low-mass supergiants in a late stage of evolution. They are probably contracting to become white dwarfs following a violent phase of evolution which caused them to become hydrogen-deficient giants, possibly R CrB stars. Using the latest generation of models for spherically expanding stellar atmospheres, we set out to measure mass-loss rates for a representative fraction of these stars. We have used high-resolution ultraviolet and optical spectra, and ultraviolet, optical and near-infrared photometry from a variety of archives. Overall atmospheric parameters have mostly been taken from previous analyses and checked for consistency. Mass-loss rates were measured by fitting the P-Cygni and asymmetric profiles of C, N and Si ultraviolet resonance lines and lie in the range 10-10 - 10-7 M\odot yr-1. These rates follow a Castor-type (M ∝ L1.5) relation marking a lower limit for the mass loss from hot stars of all kinds. The mass-loss rates of the studied stars also show a strong correlation with their proximity to the Eddington limit. There is no firm evidence for variability in the stellar wind, although photospheric pulsations have been reported in many cases.