Radio evidence of recent mass ejection from η Carinae

The luminous blue variable eta Carinae is almost certainly a double star: a hot secondary in an eccentric orbit around a massive primary. Radio observations with the Australia Telescope Compact Array at a wavelength of 3 cm, covering the period from 1992 to 2002, suggest that at the time of last periastron, 1998.0, material was tidally lifted from the primary star into its equatorial disc.