Category Science

What is a Black Hole?

A Black Hole is the extremely massive remnant of a dying star. A Black Hole is so massive that its gravity prevents anything from escaping. Not even light can escape from a Black Hole. In other words, the escape velocity of a Black Hole is greater than that of light.

How did the Black Hole get its name?

A Black Hole is actually no light to radiate and appears dark. Also anything falling into it cannot get out ever.

What is the alternative name for a Black Hole?

A Black Hole is actually a star which has collapsed beyond the neutron star stage. It is therefore also called a collapsed star or “Collapsar” for brevity. If the entire Earth collapses to form a neutron star it would have a diameter of 200 meters. If it further collapses to from a Black hole, it would be just the size of a golf ball.

What is the boundary of Black Hole?

Using Einstein’s General Theory of Relatively, it is possible to calculate, for a known amount of matter in the Black Hole, the distance at which the escape velocity is equal to the speed of light. This radius is the boundary of the Black Hole. Any object going closer to it than the Schwarzchild radius must fall into the Black Hole. Hence the boundary of a Black Hole is not actually the boundary of a solid body but the boundary of the region of space from which nothing can escape. The larger the mass of the Black Hole, the greater will be its Schwarzchild radius.

Can a Black Hole expand?

The Schwarzchild radius of a Black Hole depends on the total mass in the Black Hole. It matter in the vicinity of a Black Hole falls into it, the mass of the Black Hole will increase and it will expand.

Can a Black Hole shrink?

A Black Hole maintains its enormous gravity at the expense of its internal energy. Hence a Black Hole standing by itself in space will slowly start shrinking and eventually disappear out of existence when its mass is consumed entirely.

What is a neutron star?

After a supernova explosion, the collapsed core of the star is called a neutron star. The matter in a neutron star is so severely compressed that the entire star would have a diameter of about 10 km. the density of a neutron star is incredibly large and consists of only neutrons since protons and electrons also fuse to form neutrons.

What is the ultimate fate of a neutron star?

A neutron star radiates away its internal energy as no fusion takes place. As the internal energy of the neutron star depletes, it cools and ends up as a black neutron star similar to a black dwarf, but more dense.

What is the maximum limit for the mass of a neutron star?

The maximum possible mass of neutron star is 3.2 times the mass of the Sun.

How does a star evolve whose final mass exceeds the maximum limit of mass for a neutron star?

When the final mass of a star exceeds the limit of mass for a neutron star, it becomes a Black Hole instead of a neutron star.

What causes the sudden collapse of a when it becomes a supernova?

When the star starts to collapse, its temperature starts increasing and it starts radiating more energy. However, beyond a critical temperature mostly of the radiation is in the form of neutrino particles have no measurable mass or electric charge and hence offer no outward resistance to the inward gravitational force which can thereafter unchecked.

After a supernova fades, is there any evidence of its existence other than a neutron star?

The turbulent expanding cloud of matter thrown out by a supernova can sometimes be detected from Earth after the supernova has faded.

How cataclysmic is a supernova explosion?

When a star becomes a supernova, its luminosity may increase by one hundred million times. A supernova can even become bright enough to be seen in daylight. The explosion is very sudden and occurs in a matter of days and gradually loses its brightness within a few months.

How frequency do supernovae occur?

The average frequency of a supernova in a galaxy like the Milky Way is about three super-novae per centaury. Three spectacular supernovas, recorded in our galaxy, occurred in 1054, 1573 and 1604.

What are the second generation stars?

First generation stars were the originally formed ones after the Big Bang. Stars formed from matter remaining after the disintegration of first generation stars are classifies as second generation stars.

What are the characteristics of second generation stars?

A first generation star will only contain the elements up to iron. When the star disintegrates after becoming a supernova, the debris will contain the heavier elements. The debris may again coalesce to form another star which would be called a second generation star.

Is the Sun a second generation star?

The matter in the Sun and planets contains elements heavier than iron and hence the sun can be said to be a second generation star. The matter in the Solar System (including the matter in our bodies) was once part of a supernova.