The most famous ‘supernova impostor’ of all could have died back in the 1840s. Here’s what we think kept it alive.
In all of astronomy, no stellar event releases more energy than a supernova.
Humanity hasn’t witnessed a naked-eye supernova within our galaxy since 1604, but Eta Carinae came close.
In 1843, it brightened to become the second brightest star in the sky, gradually fading away by 1857.
Almost as much energy was released as in standard supernovae, but Eta Carinae remained intact.
Even today, in 2019, its heaviest star reaches over 100 solar masses.
The star’s surroundings reveal the remnants of this recent ejection, with 10–20 solar masses expelled at speeds from 400–3,200 km/s.
In 2005, observations revealed that Eta Carinae isn’t a single star, but a binary system in a ~5.5 year mutual orbit.
The Universe gave us a delayed replay, as some of the centuries-old emitted light rebounded off of nearby gas, creating light-echoes.
It’s possible that a specific cataclysm triggered this outburst: the devouring of a third star.
This type of mass exchange could explain:
- the outburst,
- the most massive star’s survival,
- and the absence of hydrogen in its 30 solar mass companion.
With Eta Carinae still shining, future light-echoes could hold the key to solving this mystery.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.Ethan Siegel is the author of Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.