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NASA finds 'Mighty Mouse' pulsar brighter than 10 million suns

The discovery of a new unusually bright dead star leads astronomers to question assumptions about a type of cosmic radiation -- and pulsars themselves.

The pink spot in this shot of the Cigar Galaxy shows ultraluminous X-rays (ULXs) believed to come from the largest pulsar ever recorded. NASA/JPL-Caltech/SAO/NOAO

Using their space-based Nuclear Spectroscopic Telescope Array, or NuSTAR, NASA has just discovered a pulsar radiating with energy equivalent to about 10 million of our suns -- which makes it, they say, the brightest pulsar ever recorded. It was discovered in the galaxy Messier 82, which is also known as the "Cigar Galaxy" and is located about 12 million light years from Earth.

"You might think of this pulsar as the 'Mighty Mouse' of stellar remnants," said Fiona Harrison in a statement. "It has all the power of a black hole, but with much less mass." Harrison is the NuSTAR principal investigator at the California Institute of Technology in Pasadena, California.

When a super massive star is in its death throes, its core gets so dense that it explodes under the pressure, forming a brilliant supernova. Some of the old star's material blasts off into space while part of it condenses back around its core. The gravity in that core is so intense that it forces electrons and protons together to form neutrons, creating a type of dead star called (for obvious reasons) a neutron star.

Some neutron stars begin spinning very fast, sending out regular pulses of energy from their poles. These are called -- you guessed it -- pulsars.

Pulsars are similar to black holes in that they both possess tremendous gravitational fields -- although pulsars are weaker, contain much less mass and they emit light instead of gobbling it up. The newly discovered pulsar, however, is as strong as a black hole despite its smaller size. It is pulsing at the rate of 1.37 seconds.

This NASA video illustrates what a pulsar might look like:

The discovery is causing astronomers to rethink the source of something known as ultraluminous X-ray sources -- or super-bright x-rays. Prior to this discovery, they believed all ULXs came from black holes -- especially from medium-sized black holes, which were just observed for the first time in August in the same galaxy as the new pulsar, according to

But, while they were observing a supernova, the scientists accidentally discovered bright ULX pulses coming from Messier 82. Because black holes don't pulse, they've concluded that the ULXs must be coming from the pulsar.

"In the news recently, we have seen that another source of unusually bright X-rays in the M82 galaxy seems to be a medium-sized black hole," said astronomer Jeanette Gladstone of the University of Alberta, Canada. "Now, we find that the second source of bright X-rays in M82 isn't a black hole at all. This is going to challenge theorists and pave the way for a new understanding of the diversity of these fascinating objects." Gladstone wasn't related to the research, which has just been published in the October 9 edition of the journal Nature.

Astronomers are puzzled as to why what should be a small, dead star is throwing off such a tremendous amount of light and plan to use a trio of telescopes to investigate further including NASA's NuSTAR, Swift and Chandra spacecraft.

"Having a diverse array of telescopes in space means that they can help each other out," said Paul Hertz, director of NASA's astrophysics division in Washington. "When one telescope makes a discovery, others with complementary capabilities can be called in to investigate it at different wavelengths."