Observations of a Merger Sequence

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Session 23 -- Galaxies I
Oral presentation, Wednesday, January 12, 10:15-11:45, Salon IV Room (Crystal Gateway)

[23.01] Observations of a Merger Sequence

J. E. Hibbard, J. H. van Gorkom (Columbia University)

We present high quality neutral hydrogen VLA maps and deep broad-band $R$ and narrow band \Ha\ images of a sample of five galactic systems believed to be involved in progessive stages of merging. In the early stages of interaction large amounts of HI still exist within the galactic disks and the star formation is spread throughout the disks as evidenced by \Ha\ emission. The ionized gas emission takes on the appearence of plumes and arcs emenating from the nuclear regions, which are presumably the sites of interaction-induced starbursts. In the final stages the HI is almost entirely contained within the tidal features beyond the merger body, and the HI data often reveal extended tidal features not at all apparent in the optical light. Apparently, large quantities of both gas and stars are sent to large radii during such interactions, and star formation takes place abundantly in the tails. Additionallly, bound subsystems may be forming from the tidal debris.

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