Artist’s impression of a yellow supergiant in a close binary with a blue, primary series buddy star, comparable to the homes obtained for the 2019yvr progenitor system in Kilpatrick et al. (2021). If the progenitor system to 2019yvr remained in such a binary, it should have had a really close interaction that removed a big quantity of hydrogen from the yellow supergiant in the last 100 years prior to it took off as a supernova. Credit: Kavli IPMU / Aya Tsuboi
An oddly yellow pre-supernova star has actually triggered astrophysicists to re-evaluate what’s possible at the deaths of our Universe’s most huge stars. The group explains the strange star and its resulting supernova in a brand-new research study released just recently in Monthly Notices of the Royal Astronomical Society.
At completion of their lives, cool, yellow stars are generally shrouded in hydrogen, which hides the star’s hot, blue interior. But this yellow star, situated 35 million light years from Earth in the Virgo galaxy cluster, was inexplicably lacking this important hydrogen layer at the time of its surge.
“We haven’t seen this scenario before,” stated Charles Kilpatrick, postdoctoral fellow at Northwestern University’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), who led the research study. “If a star explodes without hydrogen, it should be extremely blue — really, really hot. It’s almost impossible for a star to be this cool without having hydrogen in its outer layer. We looked at every single stellar model that could explain a star like this, and every single model requires that the star had hydrogen, which, from its supernova, we know it did not. It stretches what’s physically possible.”
Kilpatrick is likewise a member of the Young Supernova Experiment, which utilizes the Pan-STARRS telescope at Haleakalā, Hawaii to capture supernovae right after they take off. After the Young Supernova Experiment identified supernova 2019yvr in the fairly close-by spiral nebula NGC 4666, the group utilized deep area images caught by NASA’s Hubble Space Telescope, which luckily currently observed this area of the sky 2 and a half years prior to the star took off.
“What massive stars do right before they explode is a big unsolved mystery,” Kilpatrick stated. “It’s rare to see this kind of star right before it explodes into a supernova.”
The Hubble images reveal the source of the supernova, an enormous star imaged simply a number of years prior to the surge. Several months after the surge nevertheless, Kilpatrick and his group found that the product ejected in the star’s last surge appeared to hit a big mass of hydrogen. This led the group to assume that the progenitor star may have expelled the hydrogen within a couple of years prior to its death.
“Astronomers have suspected that stars undergo violent eruptions or death throes in the years before we see supernovae,” Kilpatrick stated. “This star’s discovery provides some of the most direct evidence ever found that stars experience catastrophic eruptions, which cause them to lose mass before an explosion. If the star was having these eruptions, then it likely expelled its hydrogen several decades before it exploded.”
In the brand-new research study, Kilpatrick’s group likewise provides another possibility: a less huge buddy star may have removed away hydrogen from the supernova’s progenitor star. However, the group will not have the ability to look for the buddy star till after the supernova’s brightness fades, which might use up to a years.
“Unlike its normal behaviour right after it exploded, the hydrogen interaction revealed it’s kind of this oddball supernova,” Kilpatrick stated. “But it’s exceptional that we were able to find its progenitor star in Hubble data. In four or five years, I think we will be able to learn more about what happened.”
Reference: “A cool and inflated progenitor candidate for the Type Ib supernova 2019yvr at 2.6 yr before explosion” by Charles D Kilpatrick, Maria R Drout, Katie Auchettl, Georgios Dimitriadis, Ryan J Foley, David O Jones, Lindsay DeMarchi, K Decker French, Christa Gall, Jens Hjorth, Wynn V Jacobson-Galán, Raffaella Margutti, Anthony L Piro, Enrico Ramirez-Ruiz, Armin Rest and César Rojas-Bravo, 30 March 2021, Monthly Notices of the Royal Astronomical Society.
DOI: 10.1093/mnras/stab838
