Monday, June 20, 2011

Quick facts about white dwarfs

A white dwarf is the term in astronomy used to describe the last stage in the life cycle of a (massive) star like our Sun. This last stage in the life of star occurs when star sheds its outer atmosphere, leaving the glowing, gradually cooling, core as a white dwarf. For our Sun this process will begin about 5 billion years in the future.

In the last stage of their life, these massive stars have enormous density, for instance one teaspoon of white dwarf material is estimated to weigh more than a ton.

Many astronomers have specialized in studying white dwarfs mostly because they believe this research could eventually give us more exact info about the destiny and the end of our solar system as our Sun will also eventually end its life as white dwarf.

Most white dwarfs are mainly composed of the two simplest elements in universe, hydrogen and helium. However, white dwarfs can also contain elements such oxygen, nitrogen, silicon and even iron originating from the remains of planets. The scientists have even discovered a white dwarf star system where each star appears to have been stripped down to just its helium.

White dwarfs are among the oldest objects in known universe since they are the end point of life of the life cycles of most stars.

There are some scientists who believe that the best place to look for planets that can support life is around white dwarfs. What they believe is that these new planets could possibly form from a ring of debris left behind by the white dwarf.

The nearest white dwarf to Earth is so called Sirius B at a distance of about 8.5 light years.

When two white dwarfs merge, their combined mass can exceed beyond a tipping point, leading to a supernova-like explosion.