Sirius B
Star
Facts
- Spectral class
- DA (white dwarf)
- Mass
- 1.02 times the Sun
- Surface temperature
- 25,193 K
- Surface gravity
- 400,000 times Earth's
- Discovery
- Alvan Clark, 1862
Sirius B is a white dwarf of spectral class DA, with a hydrogen atmosphere: the dead core of a star that, according to models, became a white dwarf about 126 million years ago. It packs about the mass of the Sun into a diameter 90% of Earth's, and its surface is still at about 25,000 °C.
Sirius A, beside it, is about 9000 times brighter, which is why Sirius B is hard to see. Alvan Clark discovered it in 1862 while testing one of the finest telescopes of his day.