Astron. Astrophys. Suppl. Ser. 136, 519-524

Central Mg₂ indices for early-type galaxies

V. Golev ^1,2 - Ph. Prugniel ¹ - F. Simien ¹ - M. Longhetti ³

Send offprint request: Ph. Prugniel (prugniel@galaxies. univ-lyon1.fr).

1 - CRAL-Observatoire de Lyon, CNRS UMR 142, F-69561 St-Genis-Laval Cedex, France
2 - Department of Astronomy and Astronomical Observatory, University of Sofia, P.O. Box 36, BG-1504 Sofia, Bulgaria
3 - Institut d'Astrophysique de Paris, 98 bis boulevard Arago, F-75014 Paris, France

Received June 18, 1998; accepted February 1, 1999

Abstract:

We present 210 new measurements of the central absorption line-strength $\mathrm{Mg}_2$ index for 87 early-type galaxies drawn from the Prugniel & Simien (1996) sample. 28 galaxies were not observed before. The results are compared to measurements published previously as available in HYPERCAT, and rescaled to the Lick system. The mean individual internal error on these measurements is $0\mbox{$\hbox{$.\!\!^{\rm m}$}$}009\pm0\mbox{$\hbox{$.\!\!^{\rm m}$}$}003$ and the mean external error is $0\mbox{$\hbox{$.\!\!^{\rm m}$}$}012\pm0\mbox{$\hbox{$.\!\!^{\rm m}$}$}002$ for this series of measurements.

Key words: galaxies: elliptical and lenticular, cD -- galaxies: fundamental parameters -- galaxies: stellar content