BEIJING, Dec. 6 (Xinhua) — Scientists may have discovered a new type of black hole that is smaller than any known black hole in the past, according tomedia reports. Black holes often appear in so-called co-stars, evolving from two stars that once orbited each other. When a star of the co-star runs out of fuel, it may erupt in the form of a “supernova”, leaving behind an extremely high density of neutron stars.
If the mass is large enough, a black hole is so dense that even light cannot escape. However, there is a gap between the most known neutron star and the black hole with the smallest known mass, and scientists have yet to find a neutron star or black hole in between.
The researchers carefully analyzed data from about 100,000 co-stars and eventually found an unusually small black hole in a co-star system that was 3.3 times the mass of the sun. The discovery could help physicists understand the supernova processes that led to the formation of black holes, which are also key to the formation of certain elements and the evolution of the universe.
Astrophysicists analyzed data collected by the Apache Point Observatory Galaxy Evolution Experiment, or APOGEE. This includes light from about 100,000 stars in the Milky Way.
The discovery also complements the two “mega” black holes observed in 2017. The two black holes, which are 31 times the mass of the sun and 25 times the mass of the sun, are merging in a galaxy 1.8 million light-years from Earth.
Changes in the star’s spectrum can indicate that a star is orbiting another object that is likely to be invisible, such as a black hole. To find nearby stars with possible black holes, the team narrowed the range and analyzed 200 more promising stars.
The researchers collected thousands of images of these star systems. The images were taken by 20 robotic telescopes from the All-Sky Automated All Sky Survey for Supernovae project at Ohio State University.
In these image data, a stellar system stands out. The researchers named a red giant star “J05215658” that appeared to orbit a giant hidden object, about 3.3 times the mass of the sun, smaller than any black hole previously known to the scientific community.
Astrophysicists compare the current search for black holes to those who are more than 1.75 meters tall in censuses. This shows that scientists currently have very limited knowledge of the general situation of black holes. Scientists have long known that black holes are five to 15 times the mass of the sun. At the same time, neutron stars have a mass of only about 2.1 times that of the sun. If neutron stars mass at more than 2.5 times the mass of the sun, they themselves collapse to form black holes. As a result, there is a gap between the lower limit of the black hole’s possible mass and the neutron star, which is just filled by the discovery of J05215658.
This research opens up a new field of research. The discovery also complements the two “mega” black holes observed in 2017. The two black holes, which are 31 times the mass of the sun and 25 times the mass of the sun, are merging in a galaxy 1.8 million light-years from Earth.
The observation was made by the Laser Interferometry Gravitational Wave Observatory (LIGO), which consists of two telescopes in Hanford, Washington, and Livingston, Louisiana. The observations at that time, once confirmed, attracted worldwide attention. This is not only because it proves that LIGO is indeed feasible, but also because the quality involved is unprecedented to scientists.
What’s inside a black hole?
The researchers carefully analyzed data from about 100,000 co-stars and eventually found an unusually small black hole in a co-star system that was 3.3 times the mass of the sun. Above, a supermassive black hole at the center of The Galaxy A (M87) was photographed by the Event Horizon telescope in April this year
Black holes are one of the strangest objects in the universe, and their names are just apt: nothing escapes their gravity, not even light. If you get too close to the so-called event horizon, you will also be trapped or destroyed.
Under the influence of extremely large gravitational forces, the escape rate near the black hole is greater than the speed of light, making it impossible for any light to escape from the inside of the event horizon. For small black holes, you probably won’t survive at such close range. The tidal force close to the event’s horizon sits enough to stretch any substance, making it as slender as spaghetti until it becomes a string of atoms. Physicists call the process “spaghetti”. But for large black holes, such as supermassive black holes at the core of galaxies such as the Milky Way (which are tens of millions of times as mass, if not billions of times the mass of stars), passing through the horizon sparing events may not be serious.
In theory, it should be possible to enter the world of black holes from the world we know, so physicists and mathematicians have always wondered what that world looks like. They turned to Einstein’s general theory of relativity to predict the world within a black hole. The equations of general relativity are well applied until the observer reaches the center or oddspot of the black hole, where the curvature of space-time becomes infinite.