Eta Carinae flares to become the second-brightest star

Background. Eta Carinae, formerly known as η Argus, is a binary stellar system located in the constellation Carina. It was previously a fourth-magnitude star until it brightened in 1837, marking the start of the Great Eruption. The system is heavily obscured by the Homunculus Nebula, which consists of material ejected from the primary star during this event.

Observation. In March 1843, observers noted the star's sudden increase in brightness. Mackay in Calcutta described it as fully as bright as Canopus. Observations at the Cape of Good Hope indicated it peaked in brightness, surpassing Canopus, between 11 and 14 March 1843. This made it the second-brightest star in the night sky.

Aftermath. Following the peak, the star began to fade, though it brightened again in late March 1843. By 1844, its brightness was midway between Alpha and Beta Centauri. The ejection of material during the Great Eruption drastically reduced the amount of ultraviolet light entering the Carina Nebula, altering its appearance.