Small stars. Artwork of two small stars, Sirius B and Proxima Centauri, compared to the Earth and the Sun. Sirius B is a white dwarf star, an extremely hot, dense star formed from the collapsed core of a large star. It lies around 8.6 light years from Earth, and is the companion star to Sirius, the brightest star in the sky. Although it is hot it is faint due to its size, and is invisible with the naked eye. Proxima Centauri is a cool red dwarf star that is part of the Alpha Centauri system. This system is around 4.3 light years from Earth, and Proxima itself, at around 4.1 light years distant, is the closest star to the Sun. It too is invisible to the naked eye.