Triaxial Models of the Bulge of M31

A solution is derived for the problem of finding the volume brightness distribution of a stellar system whose isophotes are similar ellipses. This solution consists of similar triaxial ellipsoids. A one-parameter family of models is found for the inner 2 kpc of M3 1. One axis of the ellipsoids of constant volume brightness is assumed to be perpendicular to the disk of the galaxy. The models reproduce the observed surface brightness distribution, including the difference in position angle between the isophotes of the disk and the isophotes of the bulge. All of the models are barlike (the ratio of the two axes in the plane of the disk is 1.5 or larger). For a star in the disk at 5 kpc from the center, the nonaxisymmetric force due to the quadrupole moment of the bulge is typically about 5% of the radial force. Subject headings: galaxies: individual - galaxies: structure