Astronomy and Astrophysics – Astrophysics
Scientific paper
1995-09-26
Astronomy and Astrophysics
Astrophysics
11 pages, uuencoded, Z-compressed file
Scientific paper
10.1086/309794
We present deep images of a region around the Crab nebula made with the VLA, utilizing new imaging and deconvolution algorithms in a search for a faint radio shell. The existence of a high-velocity, hydrogen-rich envelope has been predicted to account for the low total mass and kinetic energy of the observed nebula. No radio emission was detected from an extended source outside the Crab nebula. Our limits on surface brightness are sufficiently low to rule out the existence of a shell around the Crab whose brightness is at least two orders of magnitude below SN\thinspace{1006}, the faintest historical shell-type supernova remnant. We consider models for the progenitor star and the pre-supernova environment and conclude that if a fast, outer shock exists then it has a sharply reduced efficiency at accelerating relativistic particles from the kinetic energy of the blast wave. We also looked for a steepening of the spectral index along the boundary of the Crab nebula itself, the signature of an outer shock. However, contrary to previous claims, no such steepening was found. The absence of any evidence at radio wavelengths that either the Crab nebula or a hypothetical shell is interacting with the ambient medium leads to an interpretation that the supernova of 1054 AD was a peculiar low energy event.
Cornwell Tim J.
Frail Dale A.
Goss William Miller
Kassim Namir E.
No associations
LandOfFree
Does the Crab Have a Shell? does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Does the Crab Have a Shell?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Does the Crab Have a Shell? will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-167371