HI in Arp72 and similarities with M51-type systems

TL;DR

This study uses GMRT observations to analyze the neutral hydrogen distribution and kinematics in the Arp72 galaxy system, revealing tidal features and star-forming regions, and compares it with similar M51-type systems to understand interaction models.

Contribution

It provides detailed H{ extsc i} observations of Arp72 and compares its morphology and kinematics with other M51-type systems, proposing a multiple passage interaction model.

Findings

H{ extsc i} tails and bridge are associated with star-forming regions.

Arp72 shows morphological and kinematic similarities with M51.

A multiple passage interaction model better explains the observed features.

Abstract

We present neutral hydrogen (H{\sc i}) observations with the Giant Metrewave Radio Telescope ({\it GMRT}) of the interacting galaxies NGC5996 and NGC5994, which make up the Arp72 system. Arp72 is an M51-type system and shows a complex distribution of H{\sc i} tails and a bridge due to tidal interactions. H{\sc i} column densities ranging from 0.8$-1.8\times10^{20}$ atoms cm$^{-2}$ in the eastern tidal tail to 1.7$-2\times10^{21}$ atoms cm$^{-2}$ in the bridge connecting the two galaxies, are seen to be associated with star-forming regions. We discuss the morphological and kinematic similarities of Arp72 with M51, the archetypal example of the M51-type systems, and Arp86, another M51-type system studied with the {\it GMRT}, and suggest that a multiple passage model of Salo & Laurikainen may be preferred over the classical single passage model of Toomre & Toomre, to reproduce the H{\sc i} features in Arp72 as well as in other M-51 systems depicting similar optical and H{\sc i} features.