Using a new method for hunting nearby black holes astronomers spotted a huge stellar black hole in our galaxy. Bigger than ever thought possible.
A new black hole search method turns up a monster. Scientists say this method will reveal many more black holes in the near future.
Stellar black holes come from the death of stars and despite billions of stars that exist in the Milky Way we have only discovered a handful of these black holes.
The new-found stellar-mass black hole is 70 times the mass of the Sun. The monster black hole lies 15,000 light-years from Earth and researchers call it LB-1.
LB-1 stellar black hole was discovered by a team, headed by Prof. LIU Jifeng of the National Astronomical Observatory of China of the Chinese Academy of Sciences (NAOC).
The Milky Way galaxy may contain about 100 million stellar black holes. Until now, scientists had estimated the mass of an individual stellar black hole in our galaxy at no more than 20 times that of the sun. But the discovery of LB-1 changes everything.
“Black holes of such mass should not even exist in our galaxy, according to most of the current models of stellar evolution,” said astronomer Jifeng Liu of the National Astronomical Observatory of China.
“We thought that very massive stars with the chemical composition typical of our galaxy must shed most of their gas in powerful stellar winds, as they approach the end of their life. Therefore, they should not leave behind such a massive remnant. LB-1 is twice as massive as what we thought possible. Now theorists will have to take up the challenge of explaining its formation.”
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Until recently, stellar black holes could only be spotted when they were seen eating up gas from a nearby star. This process creates powerful X-ray emissions, detectable from Earth, that reveal the presence of the collapsed object.
But the problem is that most of the stellar black holes in our galaxy aren’t eating stars. Therefore, we can’t detect them this way.
But that’s when Prof. LIU and collaborators surveyed the sky with China’s Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), looking for stars that appeared to be getting pulled towards the gravity of an invisible object.
This observational technique was first suggested by the English scientist John Michell in the 18th century but has only recently become possible thanks to technological improvements.
After using that technique, follow-up observations using the powerful Gran Telescopio Canarias in Spain and the Keck Observatory in the US revealed a star eight times heavier than our own Sun orbiting the massive black hole every 79 days.
“This discovery forces us to re-examine our models of how stellar-mass black holes form,” said LIGO Director Prof. David Reitze from the University of Florida in the U.S.
The researchers have reported their findings in Nature.