Eta Carinae

Eta Carinae is a system of at least two stars in Carina, about 7,500 light-years away, with a combined luminosity over five million times the Sun's. In its Great Eruption it brightened from 1837 and became the second-brightest star in the sky in March 1843, then faded.

The main stars orbit every 5.54 years. The primary is an unusual luminous blue variable expected to explode as a supernova.