Hot Stars in Old Stellar Populations: A Continuing Need for Intermediate Ages
Astrophysics, abstract
astro-ph/0506336
From: Scott C. Trager [view email]
Date: Wed, 15 Jun 2005 08:56:06 GMT (54kb)
Hot Stars in Old Stellar Populations: A Continuing Need for Intermediate
Ages
Authors:
S. C. Trager (1),
Guy Worthey (2),
S. M. Faber (3),
Alan Dressler (4) ((1) Kapteyn Astronomical Institute, (2) Washington State University, (3) UCO/Lick Observatory, (4) OCIW)
Comments: 8 pages, 3 figures (2 in color); accepted for publication in MNRAS
We investigate the effect of a small 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 Hbeta
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 without, but the
enhancement ratios [E/Fe] will strengthen only slightly.
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