What is Chandrasekhar's Limit?

Answer 1

The Chandrasekhar Limit, also called the Chandrasekhar mass, is the point beyond which the "electron degeneracy pressure" within a white dwarf star no longer balances the star's own gravity.

It places an upper limit on the possible mass of a white dwarf.

If a white dwarf's gravity pulls material away from a neighboring star, adding it to the white dwarf and increasing its mass, the Chandrasekhar mass (roughly 1.4 times the mass of our Sun) can eventually be reached and surpassed.

When the balance between electron degeneracy pressure and gravity ends, the force of gravity rapidly collapses the white dwarf, and the resulting pressure and density result in a violent outward explosion that destroys the white dwarf. In Astronomy, this is known as a type Ia supernova.

There have been a small number of type Ia supernovae (supernova "2007if" was the second known) which were believed to occur at masses significantly above the Chandrasekhar limit. The prevailing theory is that in these cases, two white dwarves collided, resulting in the limit being abruptly exceeded.

Answer 2

It is named after the astrophysicist Subrahmanyan Chandrasekhar.

In Simple terms: If the remnant core of a dying star has a mass lower than the Chandrasekhar Limit, then it will become a white dwarf star. Above this limit, it will explode, as a Type II supernova.

More detailed: Stars produce energy through nuclear fusion. The heat generated from these reactions prevents the gravitational collapse of the star.

Over time, the star builds up a central core of elements for which the temperature at the center of the star is not sufficient to fuse. For stars with a mass less than 8 Suns, the mass of the core will remain below the Chandrasekhar limit, and they will eventually lose mass, as planetary nebulae, until only the core remains - as a white dwarf star.

Stars with a higher mass will eventually develop a core of iron. Iron cannot be used as fuel in fusion reactions and the star collapses onto the core. The mass of the core will soon exceed the Chandrasekhar mass.

At this point the star will explode in a "core collapse" Type II supernova, leaving either a neutron star or, if the core is massive enough, a black hole.

Very Detailed: [See Link]

A Different Viewpoint: The answer above is a bit misleading.

The "Chandrasekhar Limit" is normally associated with the supernovae

called Type Ia supernovae.

The "Chandrasekhar limit" was originally worked out, by Chandrasekhar, as the limiting mass for a white dwarf star.

It's about 1.4 times the mass of our Sun.

If a white dwarf star becomes more massive than that limit, it

should explode as a supernova (called a Type 1a supernova).

This happens when a white dwarf is in a binary star system.

The white dwarf pulls material from its larger, less dense companion. When this material is enough to take the white dwarf's mass beyond the Chandrasekhar limit, the supernova explosion occurs.

There is also the "Chandrasekhar mass", which is more or less the same thing.

The Chandrasekhar mass is important in the theory of Type II supernovae.

The answer above is about only the Type II supernovae.

See the Link below: "Supernovae and the Chandrasekhar limit". There may be a bit too much detail. Just take from it what you need.

Also, see the Link below: "Type Ia Supernovae".

Answer 3

Chandrasekhar's limit is the maximum mass that a white dwarf star can have before collapsing under its own gravity and starting nuclear fusion. This limit is about 1.4 times the mass of the Sun. If a white dwarf exceeds this limit, it can collapse into a neutron star or a black hole.

Answer 4

It was proposed by Subrahmanyan Chandrasekhar, an astrophysicist and is named after him.

It is the maximum mass a white dwarf can attain before triggering a supernova.