Courtesy of CalTech Image of ultra-luminous x-ray source near center of M82. A nearby galaxy contains the remnant of a dying star that shines with the intensity of 10 million suns, which is brighter than anyone could have ever imagined.

The discovery, announced on Oct. 8 and published in the journal Nature, raises many questions and defies understanding of the physics that drives some extreme phenomena in our universe, like the ultra-luminous sources depicted above.

This new mystery stellar corpse falls into a category of rare, extremely bright sources throughout the universe called ultra-luminous x-rays. Although it's not the brightest of these sources ever observed, this particular system shines 10 times brighter than any other stellar remnant of its kind that we've found.

Ultra-luminous x-ray sources

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NASA Goddard Spaceflight Center Illustration of black hole eating star alive. The cannibalistic scene above is an artist's conception of a type of two-body, or binary, system between a black hole and a star like our sun. The black hole's immense gravitational pull attracts gas from the star and, like unraveling a ball of yarn, slowly eats the star alive. As the star's gas falls into the black hole, it forms a bright, ultra-luminous disk that astronomers observe from Earth.

This ultra-luminous disc is extremely hot, tens of millions of degrees Fahrenheit, so most of its light is in the form of high-energy x-rays. Watch the celestial murder play out in the animation below. Note how the gas located closest to the center of the black hole is the brightest. This is because the gas is moving at incredibly high speeds, which makes it extremely hot and bright.

Since the 1970s, astronomers have been detecting these bright signatures, which they call ultra-luminous x-ray (ULX) sources. Although, the origin of ULXs is still unknown, scientists suspect they could come from this type of binary system between a star and black hole.

Until now, it was also thought that sources this bright could only come from black holes because of their immense gravitational pull, but an international team of scientists have blown this theory out of the water with their latest findings, which they published in the Oct. 9 addition of the journal Nature.

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NASA, ESA, and The Hubble Heritage Team (STScI/AURA) M82 taken by Hubble Space Telescope. What's so special about this one?

About 12 million light years from Earth is the nearby galaxy M82, shown above. Toward M82's center is a binary system between a star and what experts call a rotating neutron star, or pulsar. And when the international team observed this pulsar with NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), they found that it was emitting pulses of x-rays that were brighter than any other pulsar in the known universe.

Like black holes, neutron stars form as a star that is more massive than our sun collapses in on itself at the end of it's life. However, neutron stars don't have as strong of a gravitational pull as black holes and, therefore, do not trap light. They emit pulses of light, which is what the international team observed and what makes them confident that this system is a pulsar and not something else, like a black hole.

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