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Q&A: Supernova Remnants and Neutron Stars
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Q:
I viewed the "Time-Lapse Movie Of Crab Pulsar Wind" that I found
posted at http://chandra.harvard.edu/photo/2002/0052/movies.html
In particular, I downloaded the MPEG image (
http://chandra.harvard.edu/photo/2002/0052/combinedmovie.mpg)
that can be accessed from that page and viewed it using
Microsofts Windows Media Player 6.4.07.1112.
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What I noticed is that there is a series of at least 5
repetitions of the expanding motion and it is as though
the sequence were started each time from the same point in
time. : Is the sequence a series of replayed shorter image
sequences (similar to what one often sees with satellite
images of cloud cover) or is each frame displaying an
image taken at a later time?
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I also noticed that the sequence is sometimes time
distorted... a kind of speeding up in some instances.
A:
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We have 7 sets of coordinated HST and Chandra
observations, and so to produce a movie of reasonable
length the sequence was looped several times. This also
has the advantage of allowing the same sequence of images
to be seen with varying degrees of magnification. Your
analogy to looped weather satellite images is a good one.
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This problem is almost certainly with the mpeg player on
your computer. The format for the full-sized mpeg movie is
large enough that some combinations of computers and mpeg
software produce a somewhat jerky playback. The true
interval between each of the steps in the combined movie
is about 22 days, give or take a day.
These answers were provided by the scientist who produced the
movie, Professor Jeff Hester of the Department of Physics &
Astronomy at Arizona State University.
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