What are brown dwarfs?
Brown dwarfs are celestial objects that are too large to be called planets and too small to be called stars. They have a mass less than 0.075 that of the sun, which is around 75 times the mass of Jupiter. Like stars, brown dwarfs are believed to form from a collapsing cloud of gas and dust. But as the cloud collapses, it does not form an object dense enough at its core to trigger a nuclear fusion.
In the case of a star, hydrogen is converted into helium by nuclear fusion. This is what fuels a star and causes it to shine.
Brown dwarfs, on the other hand, are not massive enough to ignite fusion. Hence, they are also called 'failed stars'.
Dimmer and cooler than stars, brown dwarfs are elusive and hard to find. Infra red sky surveys and other techniques have however, helped scientists detect hundreds of them. They are believed to be as common as stars in the universe. Some of them are companions to stars and many are isolated objects.
First discovered in 1995, brown dwarfs were hypothesised in 1663 by American astronomer Shiv Kumar.
Despite their name, brown dwarfs are not brown. They appear from deep red to magenta, depending on their temperature.
