Astron. Astrophys. Suppl. Ser. 138, 19-30

Evolutionary synthesis of simple stellar populations

Colours and indices

O.M. Kurth - U. Fritze - v. Alvensleben - K.J. Fricke

Send offprint request: O. Kurth

Universitätssternwarte Göttingen, Geismarlandstr. 11, 37083 Göttingen, Germany
e-mail: okurth@uni-sw.gwdg.de

Received March 16, 1998; accepted February 11, 1999

Abstract:

We construct evolutionary synthesis models for simple stellar populations using the evolutionary tracks from the Padova group (1993, 1994), theoretical colour calibrations from Lejeune et al. (1997, 1998) and fit functions for stellar atmospheric indices from Worthey et al. (1994).

A Monte-Carlo technique allows us to obtain a smooth time evolution of both broad band colours in UBVRIK and a series of stellar absorption features for Single Burst Stellar Populations (SSPs). We present colours and indices for SSPs with ages from $1 \ 10^9$ yrs to $1.6 \ 10^{10}$ yrs and metallicities [M/H]=-2.3, -1.7, -0.7, -0.4, 0.0 and 0.4.

Model colours and indices at an age of about a Hubble time are in good agreement with observed colours and indices of the Galactic and M 31 GCs.

Key words: Galaxy: globular cluster; open clusters galaxies: starclusters; M 31; evolution