A Sauron Study of Stars and Gas in Sa Bulges

We present results from our ongoing effort to understand the morphological and kinematical properties of early-type galaxies using the integral-field spectrograph SAURON. We discuss the relation between the stellar and gas morphology and kinematics in our sub-sample of 24 representative Sa spiral bulges. We focus on the frequency of kinematically decoupled components and on the presence of star formation in circumnuclear rings. 1. Sa bulges in the SAURON Survey The starting point of our study is the SAURON survey of nearby, early-type galaxies (de Zeeuw et al. 2002). The full sample consists of 72 galaxies divided in three morphological groups: 24 ellipticals, 24 lenticulars, and 24 Sa bulges. Within each group, half of the galaxies are drawn from the field environment, and the remaining half are representative of the cluster population. The main science driver for the survey is the study of the intrinsic shapes, velocity and metallicity distribution, and the relation between the stellar and gas kinematics to the underlying stellar populations. Most of the results of the survey up to now have focused on the 48 elliptical and lenticular galaxies (de Zeeuw et al. 2002, Emsellem et al. 2004, Cappellari et al. 2005, Sarzi et al. 2005). Here, we concentrate on the 24 Sa spiral bulges.