Near-infrared imaging and [O I] spectroscopy of IC 443 using two micron all sky survey and Infrared Space Observatory

We present near-infrared J (1.25 mum), H (1.65 mum), and K-s (2.17 mum) imaging of the entire supernova remnant IC 443 from the Two Micron All Sky Survey (2MASS), and Infrared Space Observatory (ISO) LWS observations of [O I] for 11 positions in the northeast. Near-infrared emission from IC 443 was detected in all three bands from most of the optically bright parts of the remnant, revealing a shell-like morphology, with bright K-s-band emission along the southern ridge and bright J and H along the northeastern rim. The total luminosity within the 2MASS bands is 1.3 x 10(36) ergs s(-1). These data represent the first near-infrared images that are complete in coverage of the remnant. The color and morphological structure are very different between the northeastern and southern parts. J- and H-band emission from the northeast rim is comparably bright and can be explained mostly by [Fe II] line emission. The hydrogen recombination lines, P X and Br10, should also be present in the broadband images, but probably contribute less than 10% of the J- and H-band fluxes. Strong [O I] (63 mum) lines were detected crossing the northeastern rim, with the strongest line in the northeastern shell where the near-infrared emission shows filamentary structure. In contrast, the southern ridge is dominated by K-s-band light exhibiting a clumped and knotty structure. A two excitation temperature model K-s derived from previous ISO and ground-based observations predicts that H-2 lines can explain most of K-s band and at least half of J- and H-band emission. Hence, the prominent broadband color differences arise from physically different mechanisms: atomic fine structure lines along the northeastern rim and molecular rovibrational lines along the southern ridge. Shock models imply a fast J-shock with v(s) similar to 100 km s(-1) and 10 < n(o) < 10(3)cm(-3) for the northeastern rim and a slow C-shock with v(s) similar to 30 km s(-1) and n(o) similar to 10(-4) cm(-3) for the southern ridge, respectively. The shocked H-2 line emission is well known from the southern sinuous ridge, produced by an interaction with dense molecular clouds. The large field of view and color of the 2MASS images show that the K-s-band emission extends to the east and the northeast, suggesting that the interaction extends to the inner part of the northeastern shell. Our new CO map of the inner part of the northeast quadrant shows good correspondence with the K-s-band map. The CO lines are broad, confirming that the K-s -band emission is due to shocked band H-2.