RT Journal Article
T1 Line-strength indices in bright spheroidal galaxies: Evidence for a stellar population dichotomy between spheroidal and elliptical galaxies
A1 Gorgas García, Francisco Javier
A1 Pedraz, Santos
A1 Guzmán, Rafael
A1 Cardiel López, Nicolás
A1 González, J. J.
AB We present new measurements of central line-strength indices (namely, Mg-2, (Fe), and H beta) and gradients for a sample of six bright spheroidal (Sph) galaxies in the Virgo Cluster. Comparison with similar measurements for elliptical (E) galaxies, galactic globular clusters (GGCs), and stellar population models yield the following results: (1) in contrast with bright E galaxies, bright Sph galaxies are consistent with solar abundance [Mg/Fe] ratios; (2) bright Sph galaxies exhibit metallicities ranging from values typical for metal-rich GGCs to those for E galaxies; (3) although absolute mean ages are quite model dependent, we find evidence that the stellar populations of some (if not all) Sph galaxies look significantly younger than GCCs; and (4) Mg-2 gradients of bright Sph galaxies are significantly shallower than those of E galaxies. We conclude that the dichotomy found in the structural properties of Sph and E galaxies is also observed in their stellar populations. A tentative interpretation in terms of differences in star formation histories is suggested.
PB IOP Publishing
SN 0004-637X
YR 1997
FD 1997-05-20
LK https://hdl.handle.net/20.500.14352/59538
UL https://hdl.handle.net/20.500.14352/59538
LA eng
NO © 1997. The American Astronomical Society. All rights reserved. We are grateful to the anonymous referee, A. Aragón Salamanca, J. Gallego, and R. Peletier for useful comments. The INT is operated on the island of La Palma by the RGO at the Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. This work was supported in part by the Spanish grant PB93-456. R. G. acknowledges funding from the Spanish MEC fellowship EX93-27295297 and NSF grant AST91-20005.
NO Spanish MEC
NO NSF
DS Docta Complutense
RD 6 abr 2025