Session 74 - Supernova Remnants.
Display session, Thursday, June 13
Great Hall,

## [74.07] Carbon Monoxide Observations Toward the Supernova Remnant 3C 391: Interaction Confirmed

D. J. Wilner (CfA), S. P. Reynolds (NCSU), D. A. Moffett (NRAO)

We present observations of the J = 1 \rightarrow 0 transition of CO toward the radio-bright supernova remnant 3C 391 made with the NRAO 12-m telescope. Our earlier radio continuum observations of 3C 391 showed a morphology strongly suggestive of evolution near a density discontinuity in the external medium. In this interpretation, the supernova went off near the edge of a moderately dense molecular cloud, and after a few hundred to a thousand years the blast wave broke out of the edge of the cloud to emerge as a larger, lower surface-brightness extension to the SNR. Survey data indicated nearby CO at appropriate velocities but direct evidence for interaction was lacking. Our new observations strongly support the interaction picture. CO contours drop steeply at the location of the inner edge of the SNR radio emission; the blowout'' extension is in the direction of steepest decrease of CO contours. Extensions on the bright limb of radio continuum perfectly match the edges of a strong CO condensation. A consistent picture then involves the SNR blast wave eating its way into the molecular cloud, destroying CO as it goes. The data also indicate directly that shock acceleration of electrons at least to 10 GeV or so is possible even for a blast wave encountering dense neutral material. We describe the quantitative implications of the interaction picture for 3C 391 and for SNRs in general.

^*The NRAO is operated by Associated Universities, Inc., under a cooperative agreement with the National Science Foundation.