Astronomers have found a pulsating, dead star beaming with the energy of about 10 million suns.
The star, discovered with NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), is the brightest pulsar ever recorded, the space agency said in a statement.
Pulsars are a dense stellar remnant left over from a supernova explosion - they're classified as a type of neutron star.
"You might think of this pulsar as the 'Mighty Mouse' of stellar remnants," said Fiona Harrison, the NuSTAR principal investigator at the California Institute of Technology.
"It has all the power of a black hole, but with much less mass."
The discovery appears in a new report in the 9 October issue of the journal Nature.
The find is helping astronomers better understand mysterious sources of blinding X-rays, called ultraluminous X-ray sources (ULXs). Until now, all ULXs were thought to be black holes.
The new data from NuSTAR show at least one ULX, about 12 million light-years away in the galaxy Messier 82 (M82), is actually the pulsar in question.
"The pulsar appears to be eating the equivalent of a black hole diet," said Harrison.
"This result will help us understand how black holes gorge and grow so quickly, which is an important event in the formation of galaxies and structures in the universe."
ULXs are generally thought to be black holes feeding off companion stars - a process called accretion.
They also are suspected to be the long-sought after "medium-size" black holes - missing links between smaller, stellar-size black holes and the gargantuan ones that dominate the hearts of most galaxies.
But research into the true nature of ULXs continues toward more definitive answers.
The pulsar's energy output was measured to be the equivalent of 10 million suns, or 10 times more than that observed from other X-ray pulsars.
"This is a big punch for something about the mass of our sun and the size of Pasadena," NASA said.
Astronomers aren't sure why the pulsar is burning so brightly, but a likely reason is that it's feasting on surrounding matter at an extreme rate.
Astronomers are planning follow-up observations with NASA's NuSTAR, Swift and Chandra spacecraft to find an explanation for the pulsar's bizarre behaviour, the space agency added.