What is a Black Hole?

Black hole is a cosmic body that has an extremely intense gravity from which nothing can escape from it.  The death of a massive star created the black holes.  During the death of a massive star, the stars get exhausted by the internal thermonuclear fuels in its core and then the core becomes unstable and gravitationally collapses inward. Meanwhile, the star’s outer layer was blown away. Inside the black hole, the dying star experiences the crushing weight and it reaches the point of zero volume and infinite density. This state is known as singularity. 

This article clearly explains what is a black hole, black hole types, how are black holes formed, where is black hole, facts about the black hole in detail. 

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The above image shows the appearance of M87* black hole from the earth in different periods.

About Black Hole Theory 

In 1915, Albert Einstein published the general theory of relativity, in which he described the structure of a black hole and created the black hole theory.  According to his black hole theory, the centre of a black hole is singular and it can hide the object’s surface in the event horizon.  As the escape velocity inside the event horizon is more the speed of light, even a ray of light cannot escape from the black hole into space.  Here, the velocity which is essential for a matter to jump from the gravitational field of a cosmic object is known as escape velocity.  

In 1916, the German astronomer Karl Schwarzschild named the radius of the event horizon as Schwarzschild radius by predicting the collapsed stellar bodies, which emit no radiation. The size of the  Schwarzschild radius is directly proportional to the mass of the collapsing star. According to the black hole theory, the mass of the black hole is ten times greater than the sun and its radius must be  30 km (18.6 miles).

Types of Black Holes

The black holes are of four types. They are stellar, supermassive, miniature and intermediate. In that, the stellar death is the most commonly known black hole. It was mainly formed when the stars reached the end of their lives, most of the stars will expand, lose their mass and get cool to form a white draft.  Here, the live stars are 10 to 20 times more massive than the sun. So, in the end, it becomes either super-dense neutron stars or so-called stellar-mass black holes.

How Are Black Holes Formed? 

The black holes are mainly formed when the massive stars, whose mass are more than three solar masses, attain the end of their lives.  The stars with less mass will result in less compressed bodies like white dwarfs or neutron stars. 

Black Hole Facts 

Usually, the black hole cannot be observed directly by considering its size or by its characteristics like it cannot emit light.  The black hole can be mainly observed by enormous gravitational fields on nearby matter.  For example, if a black hole is a member of a binary star system then the matter enters into it creates a companion and gets intense heat and radiates X-rays before entering into the event horizon of the black hole, further the object disappears forever.  In 1971, Cygnus X-1 is a black hole that belongs to the binary X-ray system was identified, whose mass is 14.8 times of the sun and also it can revolve about one another in the period of 5.6 days. 

Some of the black holes are of a non stellar origin. Many astronomers made research on the large volume of interstellar gases that are collected from the universe and collapsed it with the supermassive black hole. Here, the mass of gas falls rapidly into a black hole and provides 100 times more energy than the energy released during nuclear fusion. While millions or billions of solar masses of interstellar gas collapse under gravitational force,  it creates large black holes and produces enormous energy in certain galactic systems. 

The best example of such a supermassive black hole is Sagittarius A*. The Sagittarius A* is located at the centre of the Milky way galaxy.  Its mass is  4,000,000 times more than the sun. American astronomer Andrea Ghez and German astronomer Reinhard Genzel did research on this observation and received a Nobel prize for physics in 2020. Many astronomers even found supermassive black holes in the other galaxies. 

In 2017, The event horizon telescope captured the image of the supermassive black hole, which is located at the centre of the M87 galaxy, whose mass is six and half billion more than the sun. But it is only 38 billion km away from the sun.  The supermassive black hole image captured from the M87 galaxy was the first direct image of the black hole.  The universe has many other large black holes, whose mass is 10 billion times the sun. These black holes have extremely high velocities and energy effects on gas swirling at the centre of NGC 3842 and NGC 4889, which are the galaxies located near the Milky Way. 

British astrophysicist Stephen Hawking also researched the existence of a kind of non stellar black hole. According to the theory of Stephen Hawkings, the universe has numerous tiny black holes in space, whose mass is equal to or less than that of asteroids. These black holes were created during the big bang, which originated 13.8 billion years ago at an extremely high temperature and density.  These black holes are called mini black holes.  

How to Make a Black Hole? 

Since no human or human-made objects could reach near the black hole, which is situated even 1,300 light-years near the earth. Scientists have reacted to an artificial black hole inside the lab with high velocity and gravitational force. They mainly developed to study the properties of the black hole. Technion- Israel Institute of Technology also carried out many experiments and proved the observations made by Stephen Hawking on the black hole. 

This article explained what a black hole, black hole properties, facts, where is black hole in universe, the types of black holes and also described the mass of various black holes in the universe. 

FAQs on Black Hole

Q1. How are black holes created?

Stars collapse themselves and form some black hole.  The black hole was created when the massive star reached the end of its life and imploded or collapsed. Usually, black holes take zero space, but they have some mass, which includes the mass of the stars.

Q2. Who discovered a black hole?

The characteristics and first modern solution with general relativity of black hole was found by Karl Schwarzschild in 1916. In 1958, David Finkelstein published the first interpretation as a region of space.  

Q3. What is inside the black hole?

The boundary of the black hole is called the event horizon. Any object that passes through the horizon will get trapped within the black hole. The gas and dust get closer to the object and the gravity from the black hole makes them spin faster and create lots of radiation.  

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