Sirius

Sirius, also called Alpha Canis Majoris or the Dog Star, brightest star in the night sky, with apparent visual magnitude −1.46. It is a binary star in the constellation Canis Major. The bright component of the binary is a blue-white star 25.4 times as luminous as the Sun. It has a radius 1.71 times that of the Sun and a surface temperature of 9,940 kelvins (K), which is more than 4,000 K higher than that of the Sun. Its distance from the solar system is 8.6 light-years, only twice the distance of the nearest known star system beyond the Sun, the Alpha Centauri system. Its name comes from a Greek word meaning “sparkling” or “scorching.”

Sirius has a small, faint companion star appropriately called the Pup. That name signifies youth, but in fact the companion to Sirius is a dead star called a white dwarf. Once a mighty star, the Pup today is an Earth-sized ember, too faint to be seen without a telescope.