The Crab Nebula: A Supernova Remnant in Taurus

" the first year of the period Chih-Ho, the fifth moon, the day of chi-ch'ou, a guest star appeared approximately several inches  south-east of Tien-Kuan......after more than a year it gradually became invisible......"

This  record of a "guest" star  appeared in the Annals of the Sung Dynasty. It was due to the sudden appearance of a supernova witnessed by Chinese astronomers that occurred on July 4th  1054 AD . The star which reached mag -5 at its brightest could be seen in broad daylight. This was equivalent to the light of 400 million suns! The image below shows the remnant of that cataclysmic explosion some nine hundred years later. The rate of expansion of the gas cloud amounts to 50 million miles/day.

This 4x40 sec exposure with 50cm f/4  imaged on 2000 January 24th shows the intricate network of  filaments resulting from this stellar explosion . The fainter of the central pair of stars is the supernova remnant that gave rise to this nebula. This star is not only  an incredibly dense neutron star, (1 cu. inch weighing 6 billion tons!) but is also rotating at a rate of 30 times per second as evidenced by its radio emmission. It was  one of the primary candidates  for the pulsars or pulsating group of  stars, which were discovered by Jocelyn Bell in 1967.

Check out the recent VLT  crab images  from the newly commissioned 8 metre "Melipal" ESO telescope from Chile, which were taken a few days after the image that appears above. Also have a look here  where I have resampled and color coded the above image to the same scale as the ESO image which shows some of the shock waves surrounding the pulsar.