U Geminorum (U Gem ) is an eruptive variable star in the constellation Gemini. He is the prototype of a subgroup of dwarf novae and was discovered by the British astronomer John Russell Hind in 1855.
The binary star system consists of a white dwarf and a red dwarf. These two components orbit in 4 hours and 11 minutes. The result is a light change from 14.0 to 15.1 like, which is mainly a consequence of Bedeckunsgveränderlichkeit.
In an outburst, which takes place on average every 100 days, the apparent brightness can be up to 9 may increase. The cycle is highly irregular, as was the shortest interval between two eruptions 62 days, in contrast, was the longest 257 days in coming.
Even if U Geminorum is the prototype of the U Geminorum - dwarf novae as it came in 1985 to a maximum with Super Superhumps that for another subgroup of dwarf novae, the SU UMa stars, is typical.