CG J1720-67.8: Radio and Integral Field Optical Observations

Abstract

Our previous studies of the ultracompact galaxy group CG J1720-67.8 have revealed properties, which suggest that the group is in a very advanced evolutionary state. We present here new observations in the radio and optical regimes, which have been obtained in order to further investigate the dynamical and evolutionary state of the group. Velocity fields reconstructed from integral field spectra of two regions of the group, obtained with SPIRAL at the Anglo-Australian Telescope (AAT), show some degree of distortion and a considerable velocity gradient across one of the TDG candidates. Estimates of the HI content and of the overall star formation rate of the group are obtained from radio observations with the Australia Telescope Compact Array (ATCA) in the 21 cm line and in the 20 cm continuum.