Varieties of White Dwarf
Sirius B, which is at a distance of 8.6 light years away from our galaxy, is the nearest white dwarf. White dwarfs are characterized by high density and low luminosity, so they are invisible with the naked eye. The Sun is supposed to become a white dwarf during its final stage.
There are six types of white dwarfs. White dwarfs are classified as DA, DB, DC, DO, DQ and DZ on the basis of the spectral lines present. This classification was first put forward by Edward M. Sion.
- DA has abundance of Hydrogen
- DB has neutral Helium.
- DC has a continuous spectrum.
- DO has single ionized Helium.
- DQ has Carbon.
- DZ has metal, like ionized Calcium.
Usually, a white dwarf is represented by the letter D followed by any of the letters A,B,C,O,Q, and Z which denotes the characteristic material present in it and finally its effective temperature. Scientists are studying white dwarfs to learn clues about the birth of the Universe. They are a rich source of information, which have not been explored fully. (The image below is Sirius B in binary system.)