When they run out of fuel and come to the end of their lives, stars can die in a most dramatic fashion: Exploding in an epic supernova that throws out dust and gas at tremendous speeds. Astronomers often see the remnants of such supernovas, but recently the Hubble Space Telescope observed something much rarer when it captured a star in the process of going supernova.
Supernova SN 2020fqv is located in the two interacting Butterfly Galaxies, 60 million light-years away from Earth. It was first spotted in April 2020 by the Zwicky Transient Facility at the Palomar Observatory when the star was in the earliest stages of a supernova, and Hubble scientists quickly decided to turn their attention to it as well.
“We used to talk about supernova work like we were crime scene investigators, where we would show up after the fact and try to figure out what happened to that star,” explained team leader Ryan Foley of the University of California, Santa Cruz, in a statement. “This is a different situation, because we really know what’s going on and we actually see the death in real time.”
Hubble was able to catch a glimpse of the material around the star, called circumstellar material, just a few hours after the supernova had occurred. This is an incredibly rare opportunity to study what happened to the star in its final days, as this material is only visible to telescopes for a very short time.
Along with data from NASA’s exoplanet-hunting Transiting Exoplanet Survey Satellite (TESS), which was also observing the region, scientists were able to build up a picture of what happened to the star in its final years before exploding.
“Now we have this whole story about what’s happening to the star in the years before it died, through the time of death, and then the aftermath of that,” said Foley. “This is really the most detailed view of stars like this in their last moments and how they explode.”
Understanding this particular star could help us understand other stars which may be on the verge of going supernova, like our neighboring star Betelgeuse which some people thought could be about to go supernova in 2019 (though in that case, the star’s odd behavior turned out to be due to a cloud of dust rather than an imminent explosion).
“This could be a warning system,” said Foley. “So if you see a star start to shake around a bit, start acting up, then maybe we should pay more attention and really try to understand what’s going on there before it explodes. As we find more and more of these supernovas with this sort of excellent data set, we’ll be able to understand better what’s happening in the last few years of a star’s life.”