Much to everyone’s disappointment, the 2019 dimming of the red giant star Betelgeuse did not lead to this familiar star going supernova. While we missed out on a show we could all watch with our eyes, another team, using the Keck Observatory massive scopes, was able to watch a red giant star transition – as Betelguese will one day transition – from a blobby red giant to a spectacular type II supernova. This is the celestial version of a glow-up.

In a new paper in the Astrophysical Journal, researchers led by W.V. Jacob-Galan published their description of this event, which is designated SN 2020tlf.

In the summer of 2020, the Pan-STARR Survey noted a massive red giant emitting a huge amount of light and while monitoring it, caught the detonation in Fall 2020. They then hopped on the scene with the KeckObservatory’s Low-Resolution Imaging Spectrograph.

The detailed observations will provide new insights into the detailed evolution of a star in its final moments and offer a hint at how we can gather more of these observations. According to Jacobson-Galan: It’s like watching a ticking time bomb. We’ve never confirmed such violent activity in a dying red supergiant star where we see it produce such a luminous emission, then collapse and combust, until now.

Put another way, we need to watch for Betelguese to get brighter, not dimmer when it is about to explode.

Jacobson-Galan goes on to add: I am most excited by all of the new ‘unknowns’ that have been unlocked by this discovery. Detecting more events like SN 2020tlf will dramatically impact how we define the final months of stellar evolution, uniting observers and theorists in the quest to solve the mystery of how massive stars spend the final moments of their lives.

More Information

Keck Observatory press release

“Final Moments. I. Precursor Emission, Envelope Inflation, and Enhanced Mass Loss Preceding the Luminous Type II Supernova 2020tlf,” W. V. Jacobson-Galán et al., 2022 January 6, The Astrophysical Journal