IAU Symposium Abstract S186-048T


Neutral Hydrogen Observations of ``Shell Galaxies''


D. Schiminovich1, J. H. van Gorkom2, J. M. van der Hulst3
1 Department of Physics, Columbia University < schmin@astro.columbia.edu >
2 Department of Astronomy, Columbia University < jvangork@astro.columbia.edu >
3 Kapteyn Astronomical Institute, University of Groningen < vdhulst@astro.rug.nl >



I will describe an ongoing survey to map the distribution and kinematics of neutral hydrogen (HI) in a sample of "Shell galaxies". In most of the detected systems, the HI morphology is extended with respect to the main body with gas kinematics that are surprisingly regular. Seven of these systems (Arp 227, NGC 5018, NGC 1210, NGC 2865, Arp 230, Cen A and MCG-5-7-1) will be described in detail. In several cases we identify HI associated with the shell features. In all cases the distribution and kinematics of the HI provides substantial insight into the type of event that created the shells. Merging (major and minor, with fallback) and accretion of material from nearby galaxies are processes implicated by our HI data.