Neutral Hydrogen Observations of Interacting Galaxies: Arp 279 and Arp 263

Jonathan Hargis, Haverford College
C. E. Simpson


In this study we present atomic hydrogen (HI) observations and a preliminary analysis of the interacting galaxies Arp 279 (NGC 1253) and Arp 263 (NGC 3239). The data, obtained in March 1999 with the D-configuration of the Very Large Array (VLA), is part of a multiwavelength study of interacting galaxies and tidal dwarf formation. The observations reveal that the gas in each system is extended as far as ten galactic radii in Arp 263 and three galactic radii in Arp 279. The gas in the inner portions of the disks reveal differential rotation; the gas distribution in the outer parts, however, is perturbed. Extended tails are present in both systems indicating the presence of tidal disturbances. No tidally formed dwarf galaxies are found in these interactions. Arp 279 appears to be encountering an early stage interaction with a neighboring galaxy, Arp 279A. Arp 263, however, reveals signs of both early and late stage interactions. Higher resolution observations are needed to further investigate the properties of these interacting galaxies and do further kinematic analysis. The authors wish to thank the Southeastern Association for Research in Astronomy (SARA) and the National Science Foundation (NSF) for providing the Research Experience for Undergraduates (REU) program under which this project took place (NSF grant AST-9423922).