The Crab Nebula - Messier 1 in the Constellation Cancer

 

The Crab Nebula - HSO narrow band palette- Open University, telescope.org COAST robotic telescope. Credit Pip Stakkert Jodrell Plank Observatory

"In 1014 a large star ran out of  hydrogen gas to fuse at its core. Up until this point the outward pressure created by the nuclear fusion balanced the inward gravitational force. A catastrophic collapse occurred with a resultant explosion in a Type 11 supernova! The mass of the star at collapse was too great to have formed a 'white dwarf' star but insufficient to have created a black hole. At the centre of the Crab Nebula there is a rotating 'neutron star' called a 'Pulsar'. The above image is composed from light captured by the robotic camera-telescope combination using three separate filters, which relate to the wavelength of ionised elements - Hydrogen Alpha (656nm), Sulphur II (672nm) and Oxygen III (501nm). The image is therefore of some scientific value in identifying where these excited atoms are located within the supernova debris. In the  HSO palette; excited hydrogen atoms are shown red coloured, Sulphur shown green and Oxygen shown blue.

Hubble Space Telescope image of the centre of the Crab Nebula. the rightmost of the two bright stars at the centre of the image is the pulsar. Credit:NASA and ESA; Acknowledgment: J. Hester (ASU) and M. Weisskopf (NASA/MSFC

The Nebula is 6500 light years distant and sits within the Perseus arm of the Milky Way. It is not possible to see it with the naked eye but it is said that it may be seen with binoculars from a dark location. I however, have never been able to see it other than through a telescope eyepiece. The Crab Nebula is approximately 11 light years across and is expanding at a rate of 1,500 km per second. By comparison the pulsar at its centre has a diameter of at most 30 km. Messier 1 is a very bright source of Gamma Rays, X rays and Radio waves and the pulsar at its centre was the first to be discovered by Dr Susan Jocelyn Bell" - Kurt Thrust current Director of the Jodrell Plank Observatory..