Bibcode
Köppen, J.; Weidner, C.; Kroupa, P.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 375, Issue 2, pp. 673-684.
Fecha de publicación:
2
2007
Número de citas
164
Número de citas referidas
137
Descripción
Observations show that galaxies follow a mass-metallicity relation over
a wide range of masses. One currently favoured explanation is that less
massive galaxies are less able to retain the gas and stellar ejecta and
thus may lose the freshly produced metals in the form of galactic
outflows. Galaxies with a low current star formation rate have been
found to contain star clusters up to a lower mass limit. Since stars are
predominately born in clusters, and less massive clusters have been
found to be less likely to contain very massive stars, this implies that
in environments or at times of low star formation, the stellar initial
mass function does not extend to as high masses as during high star
formation epochs. It is found that the oxygen yield is reduced by a
factor of 30 when the star formation rate is decreased by 3 to 4 orders
of magnitude. With this concept, chemical evolution models for galaxies
of a range of masses are computed and shown to provide an excellent fit
to the mass-metallicity relation derived recently by Tremonti et al.
Furthermore, the models match the relation between galaxy mass and
effective yield. Thus, the scenario of a variable integrated stellar
initial mass function, which is based on the concept of formation of
stars in clusters, may offer an attractive alternative or partial
explanation of the mass-metallicity relation in galaxies.