The ellipticities of globular clusters in the Andromeda galaxy

¹ Department of Astronomy, Faculty of Physics, St. Kliment Okhridski University of Sofia, 5 James Bourchier street, BG-1126 Sofia, Bulgaria
² Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko chauss$\acute{\rm e}$e, BG-1784 Sofia, Bulgaria

Send offprint request to: A. Staneva

Received: 15 March 1995
Accepted: 4 October 1995

Abstract

The projected ellipticities and orientations of 173 globular clusters in the Andromeda galaxy have been determined by using isodensity contours and 2D Gaussian fitting techniques. A number of B plates taken with the 2 m Ritchey-Chretien-coud reflector of the Bulgarian National Astronomical Observatory were digitized and processed for each cluster. The derived ellipticities and orientations are presented in the form of a catalogue. The projected ellipticities of M 31 GCs lie between with mean value . It may be concluded that the most globular clusters in the Andromeda galaxy are quite spherical. The derived orientations do not show a preference with respect to the center of M 31. Some correlations of the ellipticity with other clusters parameters are discussed. The ellipticities determined in this work are compared with those in other Local Group galaxies.