2002/11/22 by S. Cassisi, H. Schlattl, M. Salaris +2 · 4 citations
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/346200
published as Astrophys.J. 582 (2003) L43-L46 · 4 pages, 2 figures, uses emulateapj.sty; accepted for publication in ApJL
arxiv created 2002/11/22 · openalex publication_date 2002/11/27 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
The core helium flash in low-mass stars with extreme mass loss occurs after the tip of the red giant branch, when the H-rich envelope is very thin. The low efficiency of the H-shell source enables the He flash-driven convective zone to penetrate H-rich layers and trigger a thermonuclear runaway, resulting in a subsequent surface enrichment with He and C. In this Letter, we present the first full computations of Population II low-mass stellar models through this phase. Models experiencing this dredge-up event are significantly hotter than their counterparts with H-rich envelopes, which makes them promising candidates for explaining the existence of stars observed beyond the canonical blue end of the horizontal branch ("blue hook stars"). Moreover, this temperature difference could explain the observed gap in M V between extreme blue horizontal-branch and blue hook stars. A first comparison with spectroscopic observations of blue hook stars in the globular cluster ω Cen is also presented.