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We present new optical long-slit data along 6 position angles of the bulgeregion of M31. We derive accurate stellar and gas kinematics reaching 5 arcminfrom the center, where the disk light contribution is always less than 30%, andout to 8 arcmin along the major axis, where the disk makes 55% of the totallight. We show that the velocity dispersions of McElroy (1983) are severelyunderestimated (by up to 50 km/s) and previous dynamical models haveunderestimated the stellar mass of M31's bulge by a factor 2. Moreover, thelight-weighted velocity dispersion of the galaxy grows to 166 km/s, thusreducing the discrepancy between the predicted and measured mass of the blackhole at the center of M31. The kinematic position angle varies with distance,pointing to triaxiality. We detect gas counterrotation near the bulge minoraxis. We measure eight emission-corrected Lick indices. They are approximatelyconstant on circles. We derive the age, metallicity and alpha-elementoverabundance profiles. Except for the region in the inner arcsecs of thegalaxy, the bulge of M31 is uniformly old (>12 Gyr, with many best-fit ages atthe model grid limit of 15 Gyr), slightly alpha-elements overabundant([alpha/Fe]~0.2) and at solar metallicity, in agreement with studies of theresolved stellar components. The predicted u-g, g-r and r-i Sloan colorprofiles match reasonably well the dust-corrected observations. The stellarpopulations have approximately radially constant mass-to-light ratios (M/L_R ~4-4.5 for a Kroupa IMF), in agreement with stellar dynamical estimates based onour new velocity dispersions. In the inner arcsecs the luminosity-weighted agedrops to 4-8 Gyr, while the metallicity increases to above 3 times the solarvalue.

The old and heavy bulge of M31 I. Kinematics and stellar populations