Astronomers have tracked a star’s dying agony until it exploded into a supernova

In the famous series once upon a time in space » by Albert Barillé, Humanity of the XXXI^and century has the chance to witness the transformations of a star unstable just before it explodes into supernova for the first time in its history, an event which, moreover, does not statistically occur in the Milky Way only about once a century.

Reality has just partly caught up with fiction already in the 21st century.^and century, as shown in an article published in The Astrophysical Journal, in free access deposited on arXiv, and coming from a team ofastronomers conducted by researchers from Northwestern University and the University of California at Berkeley (UC Berkeley).

It all started in the summer of 2020 with the detection of a particularly bright star using Pan Starrs (acronym of Panoramic Survey Telescope And Rapid Response System, “Panoramic Survey Telescope and Rapid Response System”), an astronomical survey program whose objective is to perform astrometry and photometry for transient events of a large portion of the sky, almost continuously with a telescope located at the top of Haleakalā, Hawaii.

A red supergiant of 10 solar masses

The study of the star showed that it contained 10 masses solar panels and that it was located in the galaxy NGC 5731 at around 120 millionlight years of the Milky Way. In the process of supergiant red, so she was monitored for 130 days as part of the Young Supernova Experiment (YSE) conducted with Pan-Starrs. The star eventually became a type supernova NS II at the end of this period and it was then also observed with the instruments of the WM Keck Observatory on the Maunakea, also in Hawaii.

The importance of the discovery can be read through the declarations of Wynn Jacobson-Galan, an NSF graduate researcher at UC Berkeley and senior author of the article in The Astrophysical Journal : “ This is a breakthrough in our understanding of what massive stars do moments before they die. Direct detection of pre-supernova activity in a red supergiant star has never before been seen in an ordinary Type II supernova. For the first time, we saw a red supergiant star explode ! »

According to the press release from WM Keck Observatory About the supernova that was dubbed SN 2020tlf, the measurements made challenge our previous ideas about how red supergiant stars evolve just before exploding. All previous observations did not show any warning signs, that is, significant changes in the activity of the SN II progenitor stars that could lead to the belief that the thermonuclear explosion was imminent. The stars were quiet, with no analogues of strong solar flares.

But the case of SN 2020tlf, unless we had the chance to observe its star really in the last moments before the explosion, suggests that at least some massive stars must have their convective equilibrium seriously altered little time before the stellar catastrophe. Indeed, the Pan-Starrs data already showed strong plasma ejections from the parent star and shortly after the explosion the Keck also showed the presence of a dense circumstellar environment around the ongoing explosion, confirming the massive ejection of matter previously.

” Detecting more events like SN 2020tlf will have a huge impact on how we define the last months of stellar evolution, uniting observers and theorists in the quest to solve the mystery of how massive stars spend the last moments of their life concludes Jacobson-Galán.

The study of SN 2020tlf joins that of another supernova studied with Hubble.