Published: Wed, December 04, 2019
Sci-tech | By Patricia Wade

China Focus: Chinese astronomers discover unexpected huge stellar black hole

China Focus: Chinese astronomers discover unexpected huge stellar black hole

In October, researchers discovered what they believe to be a new type of black hole, smaller than the other kinds.

The team, headed by Liu Jifeng, of the National Astronomical Observatory of the Chinese Academy of Sciences (NAOC), spotted the black hole, which has a mass 70 times greater than the Sun.

Located some 15,000 light years from Earth, the so-called LB-1 black hole is more than three times as massive as expected.

The discovery was a big surprise. The size is much bigger than a black hole that can possibly exist in the Milky Way. Due to this process, they should not be capable of leaving behind a remnant that can collapse into a 70 solar mass black hole. He added: "LB-1 is twice as massive as we thought possible, and now theorists will have to face the challenge of explaining their training".

Stellar black holes are believed to be commonly scattered across the universe, but they are hard to detect because they do not normally emit X-rays - only doing so when they gobble up gas from a star that has ventured close enough.

The M87 supermassive black hole imaged earlier this year. Astronomers made a decision to set the upper limit of stellar black hole mass at approximately 30 to 40 solar masses.

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To circumvent this problem, Liu & Co. used China's Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) for a needle-in-a-haystack search for stars orbiting an invisible object pulled by its gravity.

This observational technique was first proposed by the visionary English scientist John Michell in 1783, but it has only become feasible with recent technological improvements in telescopes and detectors. Liu's staff, nonetheless, sought out stars that are orbiting inactive black holes, that are obvious exclusively by their gravitational pull.

Once an unusual star orbit was detected, the team used two of the biggest telescopes in the world - one located in Spain and the other in the U.S. - to assess the properties of the invisible object. These black holes truly live up to their name, as they can tip the scales at millions to tens of billions of times more massive than our Sun. This is a relatively uncommon activity, meaning most black holes have gone undetected. The object then explodes in a supernova, throwing off its outer layers, abandoning about a 4-5 solar mass core, which falls onto itself to create a black hole. Could LB-1 have taken shape from a similar black hole merger before the humanity discovered how to identify gravitational waves?

This discovery forces us to re-examine our models of how stellar-mass black holes form. This discovery along with the LIGO-Virgo detections of binary black holes has pointed towards a new beginning of the understanding of black hole astrophysics.

Scientists from China, the United States, Spain, Australia, Italy, Poland and the Netherlands participated in the research.

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