The system contains at least two stars, of which the primary is a luminous blue variable (LBV) that initially had around 150 solar masses, of which it has lost at least 30. A hot supergiant of about 30 solar masses is in orbit around the primary. An enormous thick red nebula surrounding Eta Carinae makes it impossible to see this companion optically, but the dumbell-shaped gas cloud is formed by two stars. 