8-12 juin, 2014


An extremely optically dim gas-rich tidal feature in NGC 871/7

Karen Lee-Waddell (Queen's University / RMC)

Kristine Spekkens (RMC), Jean-Charles Cuillandre (CFHT), John Cannon (Macalester), Martha P. Haynes (Cornell), Jonathan Sick (Queen’s), Poonam Chandra (NCRA), Narendra Nath Patra (NCRA), Sabrina Stierwalt (UVa), and Riccardo Giovanelli (Cornell)

We present GMRT HI observations and deep CFHT optical images of the gas-rich interacting group NGC 871/7. This group harbours an intriguing HI feature, AGC 749170, that has an HI mass of 10^9.1 M_sol, a dynamical-to-gas mass ratio of ~1 and no optical counterpart in previous optical imaging. However, we do detect a faint feature in our g’- and r’-band CFHT data; if it is physically associated with AGC 749170, the latter has M/L_g > 1000 M_sol/L_sol as well as a higher metallicity and a significantly younger stellar population than the other group members. These properties, as well as its spectral and spatial location with respect to its suspected parent galaxies, strongly indicate a tidal origin for AGC 749170. The HI properties of AGC 749170 resemble those of other dark or dim clouds that have been found in groups. We suggest that these clouds represent a class of relatively long-lived, HI-rich tidal remnants that survive in intermediate-density environments.
(doit être confirmé par le SOC)