LOW-FREQUENCY OBSERVATIONS OF THE VELA SUPERNOVA REMNANT AND THEIR IMPLICATIONS

We have studied the Vela supernova remnant in the light of the 34.5 MHz observations made with the GEETEE low frequency array. The flux densities of Vela X and YZ at 34.5 MHz are estimated to be 1800 and 3900 Jy respectively. These values, along with those from earlier observations at higher frequencies, imply spectral indices (S proportional nu-alpha) of -0.16 +/- 0.02 for Vela X and -0.53 +/- 0.03 for Vela YZ. This situation is further substantiated by the spectral-index distribution over the region obtained between 34.5 and 408 MHz. The spectral-index estimates, along with other known characteristics, strengthen the earlier hypothesis that Vela X is a plerion, while Vela YZ is a typical shell-type supernova remnant. We discuss the implications of this result.