Astronomers studying black holes of the Milky Way Galaxy, have discovered a new type of black hole. The blackhole might be smaller than the previously discovered ones.
The blackhole is around 3.3 times bigger than the Sun, and is located about 10,000 light years away in the outer edge of the Milky Way’s disk.
“It is always interesting in astronomy to look in a new way, and you find a new type of thing,” said Todd Thompson, the lead writer who is also the professor at the Ohio State University.
“It makes you wonder that all your ways of looking were biased.”
Most of the black holes that have been discovered were 15 times bigger than Sun. Black holes of this size are comparatively easier to spot. When they closely orbit stars in binary systems, holes pull material off their companions. This accretion process emits luminous X-ray radiation that can be observed through telescopes.
The ones which are only 2-3 times bigger than the Sun don’t emit the X-ray radiation, which make them invisible to scientists.
When a star explodes in supernova its afterlife can be known by its mass. Smaller transpire into neutron stars, while the larger ones become black hole. The neutron stars are super-dense spheres. Scientists are yet not aware about the intermediary process in which star becomes a neutron star and then transforms into black hole.
“We have wondered whether there is anything between the biggest neutron stars and the smallest ones.” “This suggests that there is a gap.”
In order to fill this gap, Thompson’ s team have recorded observations of 10,000 stars in the Milky Way through Apache Point Observatory Galactic Evolution Experiment (APOGEE).
The researchers looked out for signs of stars in the binary system in the similar manner as exoplanet researchers use to detect world around the stars.
The time narrowed down the stars to hundred by observing whether they appear to be gravitationally pulled by a nearby object or not.
Then they utilized the data received from All-Sky Automated Survey to for the further refinement for the right system. “By combining those two datasets, in one day, we discovered the star.” said Thompson.
A few other black holes have been with error margins that overlap the range of 2.5-5, so it would be premature to declare the object as the smallest black hole ever found.
“If it it gets confirmed that the black hole is 3.3 times as massive as the Sun, then it would be the smallest black hole,” said Thompson.
But as more teams have followed up on the study to employ the technique pioneered by Thompson and his colleagues, this mystery will be resolved.