Tags: Star.
U Geminorum (U Gem) in the constellation Gemini is an archetypal example of a dwarf nova. The binary star system consists of a white dwarf closely orbiting a red dwarf. Roughly every 100 days it undergoes an outburst that greatly increases its brightness. It was discovered by J.R. Hind in 1855 who initially thought it was a nova; it quickly faded below his telescope’s limiting magnitude. Its true nature was revealed three months later when it was reobserved in outburst by Pogson.
