The Radio Spectral Index and Expansion of 3C 58
NAVAL RESEARCH LAB WASHINGTON DC
Pagination or Media Count:
We present new observations of the plerionic supernova remnant 3C 58 with the VLA at 74 and 327 MHz. In addition, we re-reduced earlier observations at 1.4 and 4.9 GHz taken in 1973 and 1984. Comparing these various images, we find that 1 the remnant has a flat and relatively uniform spectral-index distribution, 2 any expansion of the remnant with time is significantly less than that expected for uniform, undecelerated expansion since the generally accepted explosion date in 1181 A.D., and 3 there is no evidence for a nonthermal synchrotron-emission shell generated by a supernova shock wave, with any such emission having a surface brightness of less than 1x10to the -21st power W mto the -2nd power Hzto the -1st power srto the -1st power at 327 MHz.