Astronomers Watch a Star Die and Then Explode as a Supernova – For the Very First Time

Red Supergiant Star Goes Supernova

An artist’s rendition of a red supergiant star transitioning into a Type II supernova, emitting a violent eruption of radiation and gas on its dying breath before collapsing and exploding. Credit: W. M. Keck Observatory/Adam Makarenko

It’s another first for astronomy.

For the first time, a team of astronomers has imaged in real-time as a red supergiant star reached the end of its life. They watched as the star convulsed in its death throes before finally exploding as a supernova.

And their observations contradict previous thinking about how red supergiants behave before they blow up.

Red Supergiant

An artist’s impression of a red supergiant star in the final year of its life emitting a tumultuous cloud of gas. This suggests at least some of these stars undergo significant internal changes before going supernova. Credit: W.M. Keck Observatory/Adam Makarenko

A team of astronomers watched the drama unfold through the eyes of two observatories in Hawaii: Pan-STARRS on Haleakala, Maui, and the W. M. Keck Observatory on Maunakea, Hawaii Island. Their observations were part of the Young Supernova Experiment (YSE) transient survey. They watched the supernova explosion, named SN 2020tlf, during the final 130 days leading up to its detonation.

“For the first time, we watched a red supergiant star explode!”
Wynn Jacobson-Galán, UC Berkeley

The title of the paper presenting the discovery is “Final Moments. I. Precursor Emission, Envelope Inflation, and Enhanced Mass Loss Preceding the Luminous Type II Supernova 2020tlf.” The paper is published in The Astrophysical Journal and the lead author is Wynn Jacobson-Galán, an NSF Graduate Research Fellow at UC Berkeley.

“This is a breakthrough in our understanding of what massive stars do moments before they die,” said Jacobson-Galán, in a press release. “Direct detection of pre-supernova activity in a red supergiant star has never been observed before in an ordinary Type II supernova. For the first time, we watched a red supergiant star explode!”

“It’s like watching a ticking time-bomb.”
Raffaella Margutti, UC Berkeley

The discovery dates back to the Summer of 2020. At that time, the progenitor star experienced a dramatic rise in luminosity. Pan-STARRS detected that brightening, and when Fall came around the star exploded as SN 2020tlf. The supernova is a Type II supernova, where a massive star experiences a rapid collapse and then explodes.

This video is an artist’s rendition of the red supergiant star transitioning into a Type II supernova, emitting a violent eruption of radiation and gas on its dying breath before collapsing and exploding. Credit: W. M. Keck Observatory/Adam Makarenko

The team used the Keck Observatory’s Low-Resolution Imaging Spectrometer (LRIS) to capture the supernova’s first spectrum. The LRIS data showed circumstellar material around the star when it exploded. That material is likely what Pan-STARRS saw the star ejecting in the summer before it exploded.

“Keck was instrumental in providing direct evidence of a massive star transitioning into a supernova explosion,” said senior author Raffaella Margutti, an associate professor of astronomy at UC Berkeley. “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.”

Supernova Pre and Post Explosion

This figure from the study shows the supernova pre- and post-explosion. The top panel shows the total of all electromagnetic radiation emitted by the event across all wavelengths, in green. The middle panel shows black-body temperatures in red, and the bottom panel shows the radii in blue. Credit: Jacobson-Galán et al, 2022

After the explosion, the team turned to other Keck instruments to continue their observations. Data from the DEep Imaging and Multi-Object Spectrograph (DEIMOS) and Near Infrared Echellette Spectrograph (NIRES) showed that the progenitor star was 10 times more massive than the Sun. The star is in the NGC 5731 galaxy about 120 million light-years away.

The team’s observations led to some new insight into Type II supernovae and their progenitor stars. Prior to these observations, nobody had seen a red supergiant display such a spike in luminosity and undergo such powerful eruptions before exploding. They were much more placid in their final days as if they accepted their fates.

Red supergiant stars eject material prior to core collapse. But that material ejection takes place on much longer timescales than SN 2020tlf. This supernova emitted circumstellar material (CSM) for 130 days prior to collapse, and that makes it a bit of a puzzle. The bright flash prior to the star’s explosion is somehow related to the ejected CSM, but the team of researchers isn’t certain how they all interacted.

Supernovae Artist's Impression

Artist’s impression of a Type II supernova explosion which involves the destruction of a massive supergiant star. Credit: ESO

The significant variability in the star leading up to collapse is puzzling. The powerful burst of light coming from the star prior to exploding suggests that something unknown happens in its internal structure. Whatever those changes are, they result in a mammoth ejection of gas before the star collapsed and exploded.

In their paper, the authors discuss what may have caused the ejection of gas. One possibility is wave-driven mass loss, which occurs in the late stages of stellar evolution. It occurs when the “… excitation of gravitational waves by oxygen or neon burning in the final years before SN can allow for the injection of energy into the outer stellar layers, resulting in an inflated envelope and/or eruptive mass-loss episodes,” they write. But current wave-driven models don’t match the progenitor star’s ejection of gas. They’re consistent with the progenitor star’s radius in its last 130 days, but not consistent with the burst of luminosity.

In the conclusion of their paper, the authors sum things up succinctly. “Given the progenitor mass range derived from nebular spectra, it is likely that the enhanced mass loss and precursor emission are the results of instabilities deeply rooted in the stellar interior, most likely associated with the final nuclear burning stages. Energy deposition from either gravitational waves generated in neon/oxygen burning stages or a silicon flash in the progenitor’s final 130 days could have ejected stellar material that was then detected in both pre-explosion flux and the early-time SN spectrum.”

If there’s one supernova that behaves like this, there must be more. The team’s findings mean that surveys like the Young Supernova Experiment transient survey now have a way to find more of them in the future. If the survey finds more stars ejecting material like this one, then they know to keep an eye on it to see if it collapses and explodes.

“I am most excited by all of the new ‘unknowns’ that have been unlocked by this discovery,” said Jacobson-Galán. “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.”

Adapted from an article originally published on Universe Today.

For more on this research:

41 Comments on "Astronomers Watch a Star Die and Then Explode as a Supernova – For the Very First Time"

  1. I myself think that near its core there is a sudden release of gas that illuminates the sun so bright and then it explodes.

  2. I myself think that near its core there is a sudden release of all gas that was trapped which illuminates the sun so bright making the sun then explode more viciously. But what do I know.

  3. Were could I get a day job like….. watching supernova. Fantastic work, patience patience n then bang🌝🌟⚪🔵🟣🟢🟠🟡🔴amazing. A lifelong millions or billions gone bang,🌞 🌤

    • Stars that go supernova are millions of years old, not billions, because they go through their nuclear material much more quickly than the stars of the size of our Sun.

  4. What should be the effect on its temperature. That as far as I think the process of wave-driven mass loss the body temperature falls down rapidly almost at absolute temperature?
    Why the temperature of star goes up rapidly by losing gases through driven wave mass loss ???

  5. What a dream…I’d love to watch the death of a super giant!

  6. I’m pretty sure they mean gravity waves, not gravitational waves

  7. Sure are a lot of artists renditions. How about actually showing it?

  8. Lysander Salamander | February 8, 2022 at 8:54 am | Reply

    There’s alot of erroneous information in this article! The astronomers did NOT observe the star itself go supernova! They recorded an event via radio spectrometry that APPEARS to have been a red giant going supernova. There is NO video of the event…. only speculation.

  9. I am getting sick of these articles claiming astronomers “watched” something but we get an “artist’s representation. What they watched was spectrographic data on a screen, not sci-fi movie explosions. If you’re going to report on science, stay real.

    • LilyCaliber@gab | February 8, 2022 at 10:29 am | Reply

      @edward bear You took the words and thoughts right outta my head! Thank you. I despair whenever I see these ” made for TV & marketing” VERY unscientific ( and often embarrassing misstatements ( intentional?) With these click bait titles. The corruption of science and transforming every aspect of it into a political statement renders these astounding and PROFOUNDLY interesting observations into meaningless and terribly oversimplified advertising for the bureaucracy of hoarding and suppressing the knowledge of new discovery.

  10. DANIEL S GRAVES | February 8, 2022 at 10:22 am | Reply

    Completely agree…”observation” of data depicting a supernova 60 million years before the last TREX walked the earth!

  11. This is pretty scary. The earth will have the same ending according to the Bible. Read all about it. Not to be selfish but I hope it doesn’t happen in my time here on earth. I hope all my relatives are closer to God by that time.

    • And you have judged your relatives as immoral. I say get off your high horse and find some humility. I find it strange that you people who profess faith in Jesus know so little about what he taught.

      • Aww how quick you are to judge a persons words. Based on the fact this person stated that they hope it never happens in their lifetime, and hopes that their relatives are closer to God, says to me that TODAY people have all but removed God from their lives, but hope that in the FUTURE mankind has once again developed a much deeper relationship with God.

        • Kenneth R Conner | February 10, 2022 at 10:20 am | Reply

          Unfortunately religion perverts the very nature of God into a device of power, control and straight up brain washing so that one man may dominate another. Religion has been the death of God. Can you imagine not taking a wife and having children? The very embodyment of God’s gift to us, to completely reject it and claim that you are the spiritual leader of “Gods” faith and deliverer of his “message”? It’s so f*cking backward. You could not create a bigger insult to God, to just throw his gift in his face and then molest the hearts of man through fear, torture and inquisition to push a book that’s a scaffolding for 7 words. Just 7. “From God, to the Pope, to man.” Rome never lost her power, her empire is stretched across the globe. Why is this s*** so hard to see? God is love. Give Love. That’s all a Bible, quoran (sp), or “scripture” needs to say. 2 words. Apply it every situation, like this one which has to be tough love, to break that hardend armor of ignorance. It’s supposed to be the basis of Christ’s own teaching and it gets turned into so much hate. The rapists of little boys raging about the evil of homosexuality? People who reject life from even before conception condemning a girl to the flaming pits of hell for aborting her baby. God is NOT judging any of us, why must we judge each other? We need God. But let’s lose the f***ing religion.

  12. What is sad of course, is that for us this is just an interesting event, but for thousands or millions of planets, no doubt with life on some of them, we’re evaporated, or sterilised killing perhaps billions of creatures.

    • Interesting thought. I believe it was Ray Bradbury ( May have been A.C. Clarke) who wrote a short story titled” The Star “ about the discovery of a dead planet which had been the home of an advanced beneficent civilization destroyed by a supernova & it was calculated that star had been “the star” in the east…yada… yada… yada Good story Interesting concept. In the words of Stony Stevenson “ Everything was beautiful & nothing hurt”

  13. Seen by astronomers but we only get artist rendition:/ still cool

  14. So typical of us humans these days to just film sonething dying and do ABSOLUTELY NOTHING to help. You make me sick.

    • Umm……what exactly would you have liked ANY human to do about a star exploding? Lmfao. Alittle over dramatic don’t you think? Lol

      • Where’s your sense of humor? His joke belongs to the kind invented by Mark Twain, who said, “Everybody’s talking about the weather, but nobody’s doing anything about it.”

    • Tony Iallonardo | February 8, 2022 at 7:01 pm | Reply

      And what would you do to “help” the situation?

  15. Otterton,
    I got it… Nerds can be so clueless.

  16. Artist’s rendering? Click bait.

  17. Babu G. Ranganathan | February 9, 2022 at 7:40 am | Reply

    Babu G. Ranganathan*
    (B.A. Bible/Biology)


    Big Bang scientists extrapolate a hypothetical scenario from a few facts. Yes, some galaxies are expanding, moving further away (Red shift), but this is not the case with the entire universe. There are galaxies in the universe running perpendicular to the rest of the galaxies, and there are galaxies even running towards us (Blue shift). All this is contrary to Big Bang. Also, if Big Bang really occurred, there should be a uniform distribution of gasses.

    The uniform distribution of gasses throughout the universe would have made sure that the gasses didn’t have enough gravitational attraction to form into planets and stars. The hypothesis of dark matter providing enough gravitational force has been increasingly discredited.

    Big Bang scientists have never proved the existence of dark matter. They only assume that it exists. The latest technologies to detect dark matter have come up empty. Big Bang scientists must hope that dark matter exists so that it would provide enough gravitational force for planets, stars, and galaxies to form.

    Big Bang scientists believe that dark matter can be the only gravitational explanation for how galaxies behave. However, other scientists have successfully shown an alternative explanation to dark matter known as MOND, which stands for Modified Newtonian Dynamics. In other words, it is not necessary to believe that 80% of the universe must be made up of dark matter in order to explain certain behavior and movement of galaxies.

    “The (galactic) structures discovered during the past few years, however, are so massive that even if CDM (Cold Dark Matter) did exist, it could not account for their formation” (Dr. Duane T. Gish, “The Big Bang Theory Collapses.” Furthermore, an explosion cannot explain the precise orbits and courses of thousands of billions of stars in billions of galaxies. Gravity may explain how that order is maintained, but mere gravity alone cannot explain the origin of that order!

    The disorder in the universe can be explained because of chance and random processes, but the order can be explained only because of intelligence and design.

    Some evolutionary astronomers believe that trillions of stars crashed into each other leaving surviving stars to find precise orderly orbits in space. Not only is this irrational, but if there was such a mass collision of stars then there would be a super mass residue of gas clouds in space to support this hypothesis. The present level of residue of gas clouds in space doesn’t support the magnitude of star deaths required for such a hypothesis. And, as already stated, the origin of stars cannot be explained by the Big Bang because of the reasons mentioned above. It’s one thing to say that stars may decay and die into random gas clouds, but it is totally different to say that gas clouds form into stars.

    Read the Internet article, ‘SMOKING GUN’ PROOF OF BIG BANG ALREADY IN DOUBT by creationist and scientist Dr. Jake Hebert. Most people don’t realize how much disagreement there is among evolutionary scientists concerning their own theories. The media doesn’t report those details, at least not to any substantial extent.

    Visit my newest Internet site: THE SCIENCE SUPPORTING CREATION


    *I have given successful lectures (with question and answer period afterwards) defending creation before evolutionist science faculty and students at various colleges and universities. I’ve been privileged to be recognized in the 24th edition of Marquis “Who’s Who in The East” for my writings on religion and science.

  18. SciFilientist
    has you’ll believing anything.
    When you wish upon a star…

  19. There’s one thing I find hard to understand. There are so many science deniers in the comments to this and many other articles, but one wonders: Why do they flock like moths to science zines to begin with? Do they really think that they’re gonna convert the majority of Americans or mankind to their ignorant and retrograde worldview? Are they really under the delusion that pointing out artists’ depictions of events in the universe will make millions exclaim: “Oh, my God, this guy is so right. How did I not see it before?”

  20. This article is clickbait. I was expecting to see the supernova exploding, instead I see an “artist’s rendition.” The first real supernova to be observed since the telescope was invented was SN 1987A

  21. I’m surprised that nowhere in the article is it clarified that the supernova bring observed happened 120 million years ago!!

  22. Now only about stars/nebulas/galaxies/planets/astriods/meteors/satelite planets/dust/gas/rays/waves/winds etc

  23. Then what about souls transition/transformation/identity before death/after death/before entering womb/before born in womb/after entering in womb/before born/before death/after death final moments

  24. What a tease, my friends! The comment section was quite entertaining, and reminds me that I still love my fellow man, in spite of recent events that proved to me many of them are not very bright, but weak and cowardly. The only bravery I did witness from doctors and real scientists unfortunately was berrated, mocked and cancelled. Folks these Globalists have very dark plans for us ALL. The enemies are already inside the Gates. It is that moment, Stand Up, Wake Up. Bless you All!

  25. If this thing was 120 million light years away, then what they saw happened 120 million years ago! What’s amazing is they happened to catch it now. Couldn’t ask for better timing.

  26. You report the truth. That is what is expected of you. Faith arguments are as old as humanity and these comments should never deter you from telling what you saw.

  27. Artist rendition, artist impression

  28. When I was young, a dying star was called Nova. When two stars wer at death’s door, they also turned into jiants same as any dying star but they were close enough to attract eachother. When they came together and exploded, It was called a Super Nova. Why and when did that change?

  29. Sorry about the double click. A scientist only needs to be told once.

  30. Debbie liebe | July 2, 2023 at 9:47 am | Reply

    IV googled this so many times, looking for confirmation….
    I’m in Victoria Aust it was 2-3 in the morning and star gazing and saw this event happen…. Two big gas like explosions about a sec apart… Lasting no more than 3sec, there was no other changes in the sky…, I had a friend with me but he wasn’t looking up I totally gasped out load asking if he saw it.. not sure what I actually saw but expecting some sort of aftermath. Yeah disappointed that theres no footage of the event. Been looking if any one else saw it too

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