Q&A: Supernova Remnants and Neutron Stars
I was looking at the NASA site that has an AVI of the time lapse
shots taken of the Crab Nebula. I have a crazy question to ask. Those shots
are 8 shots taken over a 6 month period, 1/2 light year. The caption states
the inner ring is one light year across. That would make the next ring about
2 light years across. I note that there are at least 3 "waves" that pass
the distance between the 2 rings in 6 months time. Wouldn't that mean that
the waves would be traveling at least 2 C if not faster?
It is often difficult to sort out what is moving in such images.
In the paper by J. Hester et al. in The Astrophysical Journal, Volume 577,
Issue 1, pp. L49-L52 (September 20 issue) the authors report that the wisps
move about 11-15 arcsec/year, which converts to about 0.4 light years/yr,
implying a speed of about 40% of the speed of light. This looks consistent
with the image at http://chandra.harvard.edu/photo/2002/0052/index.html