Among many things that are found in the outer space, black holes are one of the most fascinating and strangest objects. They are extremely dense with gravitational forces so strong that it is even difficult for light to escape if it comes near enough the hole. The first scientist to predict its existence in 1916 was Albert Einstein. He mentioned them in his general theory of relativity. It was American Astronomer John Wheeler who coined the term ‘black hole’ several years later in 1967. The black hole was known as a theatrical object for several years until the first physical black hole was spotted in 1971.
Later, in 2019 the first image that was ever recorded of the black hole was released by the EHT or Event Horizon Telescope Collaboration. The black hole by EHT was discovered in the center of galaxy M87. The telescope was busy examining the event horizon or the area that was closely associated with the black hole. Sudden loss of particles of light or photons was mapped in the image. This also gives astronomers a new field of research in black holes since they now know what black hole looks like.
Types of black holes
Three types of black holes have been discovered by the astronomers till now: Stellar Black Holes, Supermassive Black Holes, and Intermediate Black Holes.
Stellar Black Holes
They are small but deadly. Whenever a star burns itself through the last of itself, the object can fall into itself or may collapse. For stars that are smaller up to about 3 times the mass of the sun, the new core then becomes a white dwarf or a neutron star. But when a larger star collapses, the compression continues and a stellar black hole is created.
The black holes that are formed due to the collapse of individual stars are relatively smaller but extremely dense. There is an incredibly strong gravitational force that pulls the objects that are around the black hole. The consumption of gas and dust from nearby surrounding galaxies helps stellar black holes to continue growing in size.
Supermassive Black Holes
Supermassive black holes are millions or billions of times as massive as the sun but their diameter is the same. Such kind of black holes is believed to be lying at the center of pretty much every galaxy. The existence of the Supermassive black hole might be thousands of black holes merging together. There is a possibility that they form when large gas cloud collapses together and rapidly accreting mass.
A third option is a group of stars falling together or the collapse of a stellar cluster. Fourth, they could arise from large clusters of dark matter. Once they are formed, they collect mass from the gas and dust surrounding them which helps them to grow more enormously.
Intermediate Black Holes
Earlier, it was thought that black holes were only in bigger sizes but recent researches have concluded that there is a possibility of the existence of intermediate black holes. They can be formed when a collision of stars in a cluster takes place in a chain reaction. Several of them if formed in the same region can eventually fall together in the center of a galaxy to create a supermassive black hole.
There are many curious facts about it such as:
- The first object that was considered as a black hole was Cygnus X-1. Cygnus X-1 was the subject of a kind of wager between Kip Thorne and Stephen Hawking in 1974. Hawking was betting on the hypothesis that the source was not a black hole. In 1990, Hawking accepted defeat.
- Black holes do not suck. When something is pulled into a vacuum, the result is suction and the massive black hole is definitely not one. Instead, objects fall into it in a similar way as an object is pulled towards Earth because of gravitation.
- The star can be torn apart if it passes too close to a black hole.
- There is a possibility that miniature black holes came into existence immediately after the Big Bang. Some regions might have been squeezed into dense, tiny ones that are less massive than the sun when space was expanding rapidly.
- An estimation has been made by the astronomers that anywhere from 10 million to 1 billion stellar black holes are present in the Milky Way, with roughly three times the mass as that of the sun.
- Black holes have been a part of various science fiction books and movies. One such movie is Interstellar which was heavily relying on Thorne (American Theoretical Physicist) to incorporate science. The work done by Thorne in the movie with special effects team has helped scientists to understand how distant the star might be when it is seen near a fast-spinning black hole.