DETECTION OF PURE ROTATIONAL H-2 EMISSION FROM THE SUPERNOVA REMNANT IC-443 - FURTHER EVIDENCE FOR A PARTIALLY DISSOCIATING J-SHOCK

We present the first observation of the pure rotational 0-0 S(2) line of H-2, at 12.28 mu m, from the supernova remnant IC 443. In combinati on with near infrared observations, the pure rotational emission effec tively differentiates between broad classes of shock model. A J-shock, in which H-2 is partially dissociated, propagating into gas with H-2 density of 4 x 10(3) cm(-3) provides a good fit to the observed H-2 le vel populations but cannot be reconciled with the shock velocity infer red from H-2 line profiles. The relative H-2 level population in IC 44 3 and Orion Peak 1, discovered to be essentially identical for upper s tate energies E/k > 6000 K by Richter, Graham, and Wright, is identica l for the 0-0 S(2) line at E/k = 1681.6 K, suggesting that the underly ing nature of the two shocks as traced by H-2 observations is identica l.