Crab Nebula animation - pulsar shock blasting out at almost speed of light!

This week, Olivia Gomez, a student at St David's Catholic 6th Form College, Cardiff, has been working on Faulkes data of one of the most enigmatic objects in the sky, the Crab nebula.

The Crab Nebula is the remains of a supernova (the spectacular explosion of a massive star) which was seen from earth in 1054 A.D. The Crab is about 6,300 light-years away from the earth yet the explosion was so bright that it shone during daylight hours for 23 days and could be seen in the night sky for almost 2 years. At the centre of this nebula is a neutron star which is as massive as our sun but only the size of New York! The neutron star is called a pulsar because the star is spinning thirty times a second, throwing out energy to power the nebula.


Olivia searched through the Faulkes image archive for images of the Crab and obtained a number of good quality images that had been taken through the red filter with FTN. After aligning all of the images, she created an animation showing the changes of the nebula over time. The animation spans over 2 and a half years and clearly shows at least three distinct shock-waves moving outwards (see the red arrow in the image below) in the inner region, these are known as the `toroidal wisps'. These wisps are thought to be caused by the pulsar throwing out energy which then interacts with the nebula.



Using the position of the shock waves in each image (labeled in red), Olivia estimated the velocity of the closest shock wave, finding an outwards velocity of about 24,000 km/s which is 8% of the speed of light! Although this seems unbelievably fast, Olivia's calculation agrees with similar studies looking at the velocity of these wisps at X-ray and radio wavelengths.


To see an animation of this, click here


Olivia provided all of the images for this article. Story by Olivia Gomez and Haley Gomez.