Dead Star Has a Shockingly Strong X-Ray Pulse

Image: M82 X-2
A rare and mighty pulsar (shown in pink) can be seen at the center of the galaxy M82 in this new multi-wavelength portrait. NASA's NuSTAR mission discovered the "pulse" of the pulsar — a type of dead star — using is high-energy X-ray vision.NASA / JPL-Caltech

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A compact dead star known as a pulsar is the source for one of two superbright X-ray signals from a distant galaxy, a surprising find that could mean pulsars lie at the heart of other such known sources, scientists say.

The pulsar is the brightest of its kind ever seen, and is more than 10 million times brighter than the sun, researchers said. The discovery may even have implications for astronomers' understanding of how galaxies form, they added.

Scientists had long thought that black holes were the only ultraluminous X-ray sources, also known as ULXs. As black holes consume nearby material, they emit powerful X-rays thought to be responsible for the extremely bright ULX objects.

"Until now, nobody paid too much attention to neutron stars — pulsars — in ULXs," the lead author of the new study, Matteo Bachetti, of the Université de Toulouse in France, told by email. "From now on, people will be looking for more pulsations in these objects that might identify them as pulsars, and so neutron stars. I bet some other ULXs will be identified as pulsars in the following years." [See images of black holes around the universe]

Bachetti and his team used NASA's NuSTAR telescope to examine one of two ULXs located in the cigar-shaped galaxy M82, which lies about 12 million light-years from Earth. They found that the X-ray-emitting object, known as M82 X-2, was a dense neutron star that pulses every 1.37 seconds as it spins.

"If it were as close as the sun, we would be fried before even being born," Bachetti said.

The study appears in this week's issue of the journal Nature.

— Nola Taylor Redd,

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