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Eta Carinae is heating up

Eta Carinae is one of the biggest and brightest stars in our galaxy, with a mass over 100 times and a luminosity more than a million times that of our sun. Scientists have been observing it one way or another for almost 400 years, especially because it has large variations in brightness, and there was even a period in the 19th century called the Great Eruption when it was the second brightest star in the sky. The causes of that are still under discussion. Eta Carinae is furthermore a binary system (the secondary star is about 30 solar masses), and in 1998 it reached periastron, the point of closest approach for the two stars.

Eta Carinae has been observed with the South African Astronomical Observatory (SAAO) in the JHKL infrared bands for over forty years. From the start of observations in 1976 until periastron in 1998, astronomers saw a linear increase in the star’s brightness (although semi-periodic variations are also seen). But after 1998, the linear trend changed significantly, and the star began to brighten much faster in the J and H bands. 

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