The NGC 128 Group of Galaxies

Abstract

I present preliminary results of a 2D photometric and kinematic study of the NGC 128 group of galaxies (NGC 127, NGC 128 and NGC 130). There is strong evidence that these three galaxies are currently suffering a strong dynamical interaction. Firstly, the tidal bridge between NGC 127 and NGC 128 is strong. The spread of systemic velocities between these galaxies is also less than 200 km s^-1. Secondly, the outer isophotes of NGC 130 are strongly box-shaped at the 23 mag arcsec^-2 level and fainter in R. Moreover, the major axis rotation curve of NGC 130 is also disturbed, most likely indicating a tidal origin. Examination of rotation and velocity dispersions along five cuts perpendicular and three cuts parallel to the disk major axis of NGC 128 show that the bulge of NGC 128 is in strong cylindrical rotation to at least 6kpc (assuming D=60Mpc) above and below the plane of the disk with no clear indication of a decrease at the largest z distances measured. The bulge is also one of the most pronounced peanut-shaped known. These data provide probably the most detailed kinematic and photometric picture of a peanut-shaped galaxy yet obtained and should now be sufficient to constrain several dynamical models recently proposed for their formation.