Self-Sealing Shells: Blowouts and Blisters on the Surfaces of Leaky Wind-Blown-Bubbles and Supernova Remnants

J.M. Pittard

The University of Leeds

Blowouts can occur when a dense shell confining hot, high pressure,
gas ruptures. The venting gas inflates a blister on the surface of
the shell. Here we examine the growth of such blisters on the
surfaces of wind-blown-bubbles (WBBs) and supernova remnants (SNRs)
due to shell rupture caused by the Vishniac instability. On WBBs the
maximum relative size of the blister ($R_{rm bstall}/R$) is found
to grow linearly with time, but in many cases the blister radius
will not exceed 20 per cent of the bubble radius. Thus blowouts
initiated by the Vishniac instability are unlikely to have a major
effect on the global dynamics and properties of the bubble. The
relative size of blisters on SNRs is even smaller than on WBBs, with
blisters only growing to a radius comparable to the thickness of the
cold shell of SNRs. The small size of the SNR blowouts is, however,
in good agreement with observations of blisters in the Vela SNR. The
difference in relative size between WBB and SNR blisters is due to
the much higher speed at which gas vents out of WBBs, which
translates into a greater energy flux through a rupture of a given
size from interior gas of a given pressure. Larger blisters are
possible if shell ruptures are bigger than expected.
We expect the observed velocity structure of SNR shells to be
affected by the presence of blisters until the shell is no longer
susceptible to ruptures, since the initial expansion of blisters is
faster than the ongoing expansion of the shell.

Reference: MNRAS, in press
Status: Manuscript has been accepted


Comments: Manuscript has been accepted