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A New Formation Mechanism for the Hottest Horizontal-Branch Stars

2002/07/16 by Allen V. Sweigart, A. V. Sweigart, Sweigart, Allen V. +11
Physics and Astronomy · #Adaptive optics and wavefront sensing #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph

paper · pdf · doi:10.48550/arxiv.astro-ph/0207343

2 pages, Latex, 1 figure. To appear in "New Horizons in Globular Cluster Astronomy", eds. G. Piotto, G. Meylan, G. Djorgovski, & M. Riello, ASP Conference Series

arxiv created 2002/07/16 · openalex publication_date 2002/07/16 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Stars with very large mass loss on the red-giant branch can undergo the helium flash while descending the white-dwarf cooling curve. Under these conditions the flash convection zone will mix the hydrogen envelope with the hot helium- burning core. Such ``flash-mixed'' stars will arrive on the extreme horizontal branch (EHB) with helium- and carbon-rich envelopes and will lie at higher temperatures than the hottest canonical (i.e., unmixed) EHB stars. Flash mixing provides a new evolutionary channel for populating the hot end of the EHB and may explain the origin of the high gravity, helium-rich sdO and sdB stars.

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