Star formation and dust obscuration in the tidally distorted galaxy NGC
  2442
  Abridged: We present a detailed investigation of the morphological
distribution and level of star formation and dust obscuration in the nearby
tidally distorted galaxy NGC2442. Spitzer images in the IR at 3.6, 4.5, 5.8,
8.0um, and 24um and GALEX images at 1500\AA{} and 2300\AA{} allow us to resolve
the galaxy on scales between 240-600pc. We supplement these with archival data
in the B, J, H, and K bands. We use the 8um, 24um and FUV (1500\AA) emission to
study the star formation rate (SFR). We find that globally, these tracers of
star formation give a range of results of ~6-11\msun/yr, with the
dust-corrected FUV giving the highest value of SFR. We can reconcile the UV and
IR-based estimates by adopting a steeper UV extinction curve that lies in
between the starburst (Calzetti) and SMC extinction curves. However, the
regions of highest SFR intensity along the spiral arms are consistent with a
starburst-like extinction. Overall, the level of star-formation we find is
higher than previously published for this galaxy, by about a factor of two,
which, contrary to previous conclusions, implies that the interaction that
caused the distorted morphology of NGC2442 likely also triggered increased
levels of star-formation activity. Outside of the spiral arms, we discover what
appears to be a superbubble, ~1.7kpc across in the IRAC images. Significant
H{\alpha}, UV and IR emission in the area also suggest vigorous ongoing
star-formation. A known, recent supernova (SN1999ga) is located at the edge of
this superbubble. Although speculative at this stage, this area suggests a
large star-forming region with a morphology shaped by generations of
supernovae. Lastly, we discover an 8um (PAH) circumnuclear ring with an ~0.8kpc
radius. The H{\alpha} emission is largely concentrated inside that ring and
shows a vague spiral structure in the rest of the galaxy.
