Restarting Galaxy Formation in Arp 82: An UV, Optical and Mid-IR Study of Star Formation in NGC 2535/6

As part of our Spitzer Spirals, Bridges, and Tails project to help understand the effects of galaxy interactions on star formation, we analyze
GALEX ultraviolet, SARA optical, and Spitzer infrared images of the interacting galaxy pair Arp 82 NGC 2535/6 and compare to a numerical simulation of the interaction. We investigate the multiwavelength properties of
several individual star forming complexes clumps. Using optical and UV
colors, EWHalpha, and population synthesis models we constrain the ages
of the clumps and find that the median clump age is about 12 Myr. The
clumps have masses ranging from a few times 10^6 to 10^9 solar masses. In
general, the clumps in the tidal features have similar ages to those in the
spiral region, but are less massive. The 8 micron and 24 micron luminosities
are used to estimate the far-infrared luminosities and the star formation rates
of the clumps. The total clump star formation rate is 2.0/-0.8 solar masses
per year, while the entire Arp 82 system is forming stars at a rate of 4.9/-
2.0 solar masses per year. We find, for the first time, stars in the HI arc to the
southeast of the NGC 2535 disk. Population synthesis models indicate that
all of the observed populations have young to intermediate ages. We conclude that although the gas disks and some old stars may have formed
early-on, the progenitors may have been late-type or low surface brightness
and the evolution of these galaxies seems to have halted until the recent
encounter.