Crab Nebula

having seen the picture of the day today at
http://antwrp.gsfc.nasa.gov/apod/astropix.html
I wondered is there is any discernible expansion
showing between the oldest photos taken
and ones taken now?
|P

"Peter Bull" wrote:

having seen the picture of the day today at
http://antwrp.gsfc.nasa.gov/apod/astropix.html
I wondered is there is any discernible expansion
showing between the oldest photos taken
and ones taken now?
|P


Hi Peter

Have a look at the animation at the bottom of the following page:

http://www.la.unm.edu/~beach/astrophotos.html

Clear skies,

Adrian

In message , Peter Bull
writes
having seen the picture of the day today at
http://antwrp.gsfc.nasa.gov/apod/astropix.html
I wondered is there is any discernible expansion
showing between the oldest photos taken
and ones taken now?

There should be. The Crab is relatively young (950y) and was probably
more compact and brighter when Messier catalogued it. Optical images
should be available for the past century. You may also find more recent
radio observations at sufficiently high resolution and time baseline to
show secular motion of knots and changes within it.

Certainly such data exists for the expansion of the radio SNR Cassiopeia
A which is younger (~300y) and so expanding faster - easier to measure.

Regards,
--
Martin Brown

Peter Bull wrote:
is there is any discernible expansion

Yes.

Best,
Stephen

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"Stephen Tonkin" wrote in message
...
Peter Bull wrote:
is there is any discernible expansion

Yes.


"Expanding" slightly on this, Virginia Trimble's PhD thesis was on this
topic back in 1970-ish. I'm sure further work has been done since. A
search on ADS shoudl bring it forward, and you can read the original paper
if you want.

--
Mike Dworetsky

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Mike Dworetsky wrote:
"Expanding" slightly on this,

Expanding slightly more (from possibly fallible memory), a few years
back an amateur image (Dave Strange's?) of the Crab showed clear changes
with respect to an earlier image/photograph. This was either discussed
here or on one of the numerous astro mailing lists I have been part of
over the years.

Best,
Stephen

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+ Stephen Tonkin | ATM Resources; Astro-Tutorials; Astro Books +
+ (N51.162 E0.995) | http://astunit.com +
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Yes, not long ago there was a picture published (S&T?) that was a B&W image
from several decades ago, superimposed on a negative taken recently. If
there had not been expansion, the light and dark areas would have countered
each other (as they did with the background stars). But each of the
filaments etc showed outward movement.

Clear Skies

Chuck Taylor
Do you observe the moon?
Try the Lunar Observing Group
http://groups.yahoo.com/group/lunar-observing/

************************************
"Peter Bull" wrote in message
...
having seen the picture of the day today at
http://antwrp.gsfc.nasa.gov/apod/astropix.html
I wondered is there is any discernible expansion
showing between the oldest photos taken
and ones taken now?
|P