The star Alpha Canis Majoris, magnitude −1.44, the brightest star in the sky. It is popularly known as the Dog Star because it lies in the constellation Canis Major, the Greater Dog. It is an A1 dwarf and lies 8.6 l.y. away, making it the fifth-closest star to the Sun. Sirius has a white-dwarf companion, Sirius B, sometimes known as the Pup, which orbits it in a period of 50 years. Sirius B is of spectral type DA2, absolute magnitude 11.3, visual magnitude 8.4, and can be seen only with large telescopes when at its maximum separation from Sirius, as between the years 2020–2025.
Subjects: Astronomy and Astrophysics.