2004/11/12 by G. J. Harris, A. E. Lynas-Gray, S. Miller +2 · 5 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/427391
published as Astrophys.J. 617 (2004) L143-L146 · 12 pages, 4 figures. Accepted for publication in ApJ Letters
arxiv created 2004/11/12 · openalex publication_date 2004/11/19 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
HeH + is found to be the dominant positive ion over a wide range of temperatures and densities relevant to helium-rich white dwarfs. The inclusion of HeH + in ionization equilibrium computations increases the abundance of free electrons by a significant factor. For temperatures below 8000 K, He - free-free absorption is increased by up to a factor of 5 by the inclusion of HeH + . Illustrative model atmospheres and spectral energy distributions are computed, which show that HeH + has a strong effect on the density and pressure structure of helium-rich white dwarfs with T eff < 8000 K. The inclusion of HeH + significantly reddens spectral energy distributions and broadband color indices for models with T eff < 5500 K. This has serious implications for existing model atmospheres, synthetic spectra, and cooling curves for helium-rich white dwarfs.