SUPERNOVA-REMNANTS ASSOCIATED WITH MOLECULAR CLOUDS IN THE LARGE MAGELLANIC CLOUD

We used the Swedish-ESO Submillimeter Telescope (SEST) to search for C O emission associated with three supernova remnants (SNRs) in the Larg e Magellanic Cloud: N49, N132D, and N23. Observations were carried out in the J = 2 --> 1 rotational transition of CO (230.5 GHz) where the half-power beamwidth of the SEST is 23 ''. Molecular clouds were disco vered near N49 and N132D; no CO emission was discovered in the region we mapped near N23. The N49 cloud has a peak line temperature of 0.75 K, spatial scale of similar to 7 pc and virial mass of similar to 3 x 10(4) M.. The N132D cloud is brighter with a peak temperature of 5 K; it is also larger similar to 22 pc and considerably more massive simil ar to 2 x 10(5) M-.. The velocities derived for the clouds near N49 an d N132D, +286.0 and +264.0 km s(-1), agree well with the previously kn own velocities of the associated SNRs: +286 km s(-1) and +268 km s(-1) respectively. ROSAT X-ray images show that the ambient density into w hich the remnants are expanding appears to be significantly increased in the direction of the clouds. Taken together these observations indi cate a physical association between the remnants and their respective, presumably natal, molecular clouds. The association of N49 and N132D with dense regions of molecular material means that both were likely p roducts of short-lived progenitors that exploded as core-collapse supe rnovae.