Open AccessHot stars in old stellar populations: a continuing need for intermediate ages
Author(s) -
Trager S. C.,
Worthey Guy,
Faber S. M.,
Dressler Alan
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09288.x
Subject(s) - physics , astrophysics , metallicity , coma cluster , starlight , stars , balmer series , galaxy , stellar population , astronomy , star formation , galaxy cluster , emission spectrum , spectral line
We investigate the effect of a low‐level contamination of hot, old, metal‐poor starlight on the inferred stellar populations of early‐type galaxies in the core of the Coma Cluster. We find that the required correction to the Balmer and metal absorption‐line strengths for old, metal‐poor stars does not significantly affect the inferred age of the stellar population when the Hβ strength is large. Intermediate‐aged populations are therefore still needed to explain enhanced Balmer‐line strengths in early‐type galaxies. This gives us increased confidence in our age estimates for these objects. For galaxies with weak Balmer‐line strengths corresponding to very old populations ( t > 10 Gyr) , however, a correction for hot stars may indeed alter the inferred age, as previously suggested. Finally, the inferred metallicity [Z/H] will always be higher after any correction for old, metal‐poor starlight than if it were not taken into account, but the enhancement ratios [E/Fe] will strengthen only slightly.