Tracking the eruptions of a star that’s shed 15 times the mass of the Sun

Enlarge / The two stars of η Carinae are embedded in the nebula they've created. (credit: NASA, ESA, and the Hubble SM4 ERO Team)

"Even among Luminous Blue Variable [stars], η Car is unusual and its parameters are extreme."

That bit of science-speak roughly translates to "Even among the largest, most energetic stars, Eta Carinae has done things we can't explain, but find incredibly impressive." The top item in η Carinae's (η is the Greek letter eta) list of extreme behaviors involves producing a decades-long outburst that caused it to become the second-brightest star in the sky. This outburst released as much energy as a supernova and ejected many times the mass of the Sun. Yet somehow η Carinae remained intact.

Now, researchers have used a series of Hubble images to produce a timeline of the debris left behind by this enigmatic outburst. The new data reveals that this was just the latest in a series of eruptions, and we still can't explain why they happen.