Bibcode
DOI
Casuso, E.; Vazdekis, A.; Peletier, R. F.; Beckman, J. E.
Bibliographical reference
Astrophysical Journal v.458, p.533
Advertised on:
2
1996
Citations
33
Refereed citations
32
Description
We provide a new calibration of the metallicity dependence of the
Mg2 index in stellar systems. It is based on new isochrones
by the Padova group and the latest stellar spectral libraries. Since the
Mg2 line is one of the strongest absorption lines in the
optical spectrum, it is often used to determine metallicities of
composite stellar systems assuming a certain age. This paper allows one
to do this, with an uncertainty of about 0.1 in log Z, for an age range
between 8 and 17 Gyr. We estimate that the uncertainties of the current
Mg2 calibrations in the literature amount to another 0.15 in
log Z. Using our calibration we find, under conservative assumptions,
that the large majority of elliptical galaxies, and also many bulges of
spiral galaxies, must have Mg abundances larger than solar; this
conclusion depends very little on their star formation history. If [Mg/
Fe] = 0, the same can be said for total metallicities. If we assume that
[Mg/Fe] = 0.45, only about 38% of the ellipticals must have
metallicities (Z) larger than solar.