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The evolution of high-metallicity horizontal-branch stars and the origin of the ultraviolet light in elliptical galaxiesEvolutionary calculations of high-metallicity horizontal-branch stars show that for the relevant masses and helium abundances, post-HB evolution in the HR diagram does not proceed toward and along the AGB, but rather toward a 'slow blue phase' in the vicinity of the helium-burning main sequence, following the extinction of the hydrogen shell energy source. For solar and twice solar metallicity, the blue phase begins during the helium shell-burning phase (in agreement with the work of Brocato and Castellani and Tornambe); for 3 times solar metallicity, it begins earlier, during the helium core-burning phase. This behavior differs from what takes place at lower metallicities. The implications for high-metallicity old stellar populations in the Galactic bulge and for the integrated colors of elliptical galaxies are discussed.
Document ID
19920050418
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Horch, E. (NASA Headquarters Washington, DC United States)
Demarque, P. (NASA Headquarters Washington, DC United States)
Pinsonneault, M. (Yale University New Haven, CT, United States)
Date Acquired
August 15, 2013
Publication Date
April 1, 1992
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 388
ISSN: 0004-637X
Subject Category
ASTROPHYSICS
Funding Number(s)
CONTRACT_GRANT: NAGW-2531
Distribution Limits
Public
Copyright
Other