other query modes : |
Identifier query |
Coordinate query |
Criteria query |
Reference query |
Basic query |
Script submission |
TAP |
Output options |
Object types |
Help |
2000AJ....119.1645T - Astron. J., 119, 1645-1676 (2000/April-0)
The stellar population histories of local early-type galaxies. I. Population parameters.
TRAGER S.C., FABER S.M., WORTHEY G. and GONZALEZ J.J.
Abstract (from CDS):
SSP-equivalent ages of the González elliptical galaxies are found to vary widely, 1.5 Gyr≲t≲18 Gyr, while metallicities [Z/H] and enhancement ratios [E/Fe] are strongly peaked around <[Z/H]>=+0.26 and <[E/Fe]>=+0.20 (in an aperture of radius re/8). The enhancement ratios [E/Fe] are milder than previous estimates because of the application of nonsolar abundance corrections to both Mg b and <Fe> for the first time. While [E/Fe] is usually greater than zero, it is not the ``E'' elements that are actually enhanced but rather the Fe-peak elements that are depressed; this serves not only to weaken <Fe> but also to strengthen Mg b, accounting for the overall generally mild enhancements. Based on index strengths from the Lick/IDS galaxy library (Trager et al.), C is not depressed with Fe but rather seems to be on a par with other elements such as Mg in the E group. Gradients in stellar populations within galaxies are found to be mild, with SSP-equivalent age increasing by 25%, metallicity decreasing by <[Z/H]>=0.20 dex, and [E/Fe] remaining nearly constant out to an aperture of radius re/2 for nearly all systems.
Our ages have an overall zero-point uncertainty of at least ∼25% because of uncertainties in the stellar evolution prescription, the oxygen abundance, the effect of [E/Fe]≠0 on the isochrones, and other unknowns. However, the relative age rankings of stellar populations should be largely unaffected by these errors. In particular, the large spread in ages appears to be real and cannot be explained by contamination of Hβ by blue stragglers or hot horizontal-branch stars, or by fill-in of Hβ by emission. Correlations between these derived SSP-equivalent parameters and other galaxy observables will be discussed in future papers.
Abstract Copyright: ∼
Journal keyword(s): Galaxies: Abundances - Galaxies: Elliptical and Lenticular, cD - Galaxies: Evolution - galaxies: stellar content
Simbad objects: 49
To bookmark this query, right click on this link: simbad:2000AJ....119.1645T and select 'bookmark this link' or equivalent in the popup menu