INTERACTION BETWEEN THE SUPERNOVA REMNANT CTB-80 AND THE AMBIENT INTERSTELLAR-MEDIUM - H-I AND CO OBSERVATIONS

We performed VLA H I 21 cm line and (CO)-C-12 J = 1-0 line observations of the old supernova remnant (SNR) CTB 80. The clumpy structure of the fast, v(exp) is similar to 72 km s-1, expanding SNR shell detected by Koo et al. (1990) is found to be due to fast-moving H I clumps, which have a dense, n(H) is similar to 100 cm-3, core surrounded by a relatively diffuse envelope. These clumps are most likely the preexisting ''cold clouds'' in the ambient interstellar medium (ISM) that had been swept-up and accelerated by the SN blast wave. CO observations show that most of the molecular gas in this region is confined into two large filamentary clouds. There is no certain evidence for the interaction between the SNR and the molecular cloud. By analyzing the Arecibo H I data of Koo et al., we found that the ISM around CTB 80 is far from being uniform and homogeneous. Instead, it seems to be composed of a large cold cloud, a warm neutral medium pervaded by small cold clouds, and a tenuous hot tunnel, which is close to the McKee & Ostriker's three-phase ISM model. We discuss how the ambient ISM shaped the morphology of CTB 80 in H I, infrared, and radio continuum.