Retorne
Título
:
Strong Balmer lines in old stellar populations: no need for
young ages in ellipticals?
Conferencista:
Claudia Maraston, Universitäts-Sternwarte München, Germany
Data
:
Segunda-Feira 29/01/01
Local
:
Auditório L.B.F. Clauzet - Água Funda
Sumário
:
Comparing models of simple Stellar Populations (SSP) with observed line
strengths generally provides a tool to break the age-metallicity degeneracy
in elliptical galaxies. Due to the wide range of Balmer line strenghts
observed, ellipticals have been interpreted to exhibit an appreciable scatter
in age. In this paper, we analyze Composite Stellar Population models with a
simple mix of an old metal-rich and an old metal-poor component. We show that
these models simultaneously produce strong Balmer lines and strong metallic
lines without invoking a young population. The key to this result is that our
model are based on SSPs that better match the steep increase oh Hbeta in the
literature. Hence, the scatter of Hbeta observed in cluster and lumunous
field galaxies can be explained by a spread in the metallicity of old stellar
populations. We check our model with respect to the so-called G-dwarf problem
in ellipticals. For a galaxy subsample covering a large range in UV-V colors
we demonstrate that the addition of an old metal-poor subcomponent does not
invalidate other observational constraints like colors and the flux in the
mid-UV.