Distances from stellar kinematics for peculiar Virgo Cluster spiral galaxies

Abstract

We present distance estimates for 11 peculiar Virgo Cluster spiral galaxies based on measurements of the stellar kinematics of their central 2 kpc. Stellar circular velocities were obtained using two- integral dynamical models. Distances were obtained by comparing, at each radius, the stellar circular velocities with synthetic H alpha rotation curves derived from NIRTully- Fisher relations. The results show that most of our galaxies are locatedwithin 4 Mpc of the core of the cluster. Three of these galaxies, previously classified as `` low rotator galaxies'' or with `` truncated / compact'' HI- radial distributions, have stellar kinematicsYbased distances that are discrepant with H iYbased distances by at least 60% and are likely to be located within the virial radius of the cluster. These discrepancies appear due to very truncated gas distributions plus noncircular gas motions or gas motions not in the plane of the stellar disk, perhaps as the result of gravitational interactions. Our results show that environmental effects can significantly reduce the measured H i line widths for some disturbed cluster galaxies, thus affecting the accurate determination of distances based on gas kinematics methods.