NASA STEREO Spacecraft’s Lone View of Betelgeuse Reveals More Strange Behavior – Is Supernova Imminent?

Betelgeuse STEREO Image

An image from the Heliospheric Imager aboard NASA’s STEREO spacecraft shows the star Betelgeuse, circled. For several weeks in 2020, STEREO was the only observatory making measurements of Betelgeuse because of the spacecraft’s unique position in space. Credit: NASA/STEREO/HI

For several weeks in summer 2020, NASA’s Solar and Terrestrial Relations Observatory, or STEREO, had the solar system’s best view of the star Betelgeuse, whose extreme dimming over the past several months has intrigued scientists. STEREO’s measurements revealed more unexpected dimming by the star, further adding to the questions around Betelgeuse’s recent behavior.

Starting in late spring 2020, Betelgeuse has appeared close to the Sun in the sky because of Earth’s position in space. However, the STEREO spacecraft is currently about 70 degrees away from Earth — meaning that in late June, STEREO was in approximately the same position that Earth was in around mid-April, and could therefore see the stars that appeared in Earth’s night sky during April.

Betelgeuse Brightness 2018 2020 Chart

This figure shows measurements of Betelgeuse’s brightness from different observatories from late 2018 to present. The blue and green points represent data from ground-based observatories. The gaps in these measurements happen when Betelgeuse appears in Earth’s day sky, making it impossible to take precise brightness measurements. During this observation gap in 2020, NASA’s STEREO spacecraft — with measurements shown in red — stepped in to observe Betelgeuse from its unique vantage point, revealing unexpected dimming by the star. The 2018 data point from STEREO was found in the mission’s archival data and was used to calibrate STEREO’s measurements against other telescopes. Credit: Dupree, et al

Scientists took advantage of this unique orbital position to keep tabs on Betelgeuse while the star was invisible to Earth-bound observatories. During this period between late June and early August, STEREO observed Betelgeuse on five separate days, rolling the spacecraft for about two hours each time to place Betelgeuse in the field of view of STEREO’s Heliospheric Imager, an instrument usually used to capture images of the Sun’s outflowing material, the solar wind, as it passes by the spacecraft and towards Earth. The team shortened the instrument’s exposure time to account for Betelgeuse’s relative brightness compared to the solar wind. The instrument’s wide field of view covers about 70 degrees of sky, which allowed scientists to calibrate their measurements using steady stars in the night sky across several weeks.

STEREO’s measurements revealed that Betelgeuse is dimming again — an unexpected development so soon after its last dim period. Betelgeuse typically goes through brightness cycles lasting about 420 days, with the previous minimum in February 2020, meaning this dimming is happening unexpectedly early. These observations were reported by the science team via The Astronomer’s Telegram on July 28, 2020. This is an intriguing phenomenon that scientists will study with additional Earth-orbiting and ground-based observatories when Betelgeuse returns to the night sky in late August.

Betelgeuse Southern Region Evolving

This four-panel graphic illustrates how the southern region of the rapidly evolving, bright, red supergiant star Betelgeuse may have suddenly become fainter for several months during late 2019 and early 2020. In the first two panels, as seen in ultraviolet light with the Hubble Space Telescope, a bright, hot blob of plasma is ejected from the emergence of a huge convection cell on the star’s surface. In panel three, the outflowing, expelled gas rapidly expands outward. It cools to form an enormous cloud of obscuring dust grains. The final panel reveals the huge dust cloud blocking the light (as seen from Earth) from a quarter of the star’s surface. Illustration credit: NASA, ESA, and E. Wheatley (STScI)

Is a Supernova Imminent?

The red supergiant is destined to end its life in a supernova blast. Some astronomers think the sudden dimming may be a pre-supernova event. The star is relatively nearby, about 725 light-years away, which means the dimming would have happened around the year 1300. But its light is just reaching Earth now.

“No one knows what a star does right before it goes supernova, because it’s never been observed,” Andrea Dupree, associate director of the Center for Astrophysics | Harvard & Smithsonian (CfA), Cambridge, Massachusetts, explained. “Astronomers have sampled stars maybe a year ahead of them going supernova, but not within days or weeks before it happened. But the chance of the star going supernova anytime soon is pretty small.”

Read Hubble Finds Cause for Betelgeuse’s Mysterious Dimming for more research on Betelgeuse’s recent dimming.

15 Comments on "NASA STEREO Spacecraft’s Lone View of Betelgeuse Reveals More Strange Behavior – Is Supernova Imminent?"

  1. “But the chance of the star going supernova anytime soon is pretty small.”
    What is that supposed to mean? It’s going to happen but not tomorrow?
    What about in 2 months, 2 years or 20 years? Will we get a deadly blast of radiation from it?

    • Torbjörn Larsson | August 15, 2020 at 9:52 am | Reply

      Presumably it’s supposed to tease you to read the article on the causes of the dimming episodes (from the link, say). Or, as Ars puts it, “Astronomers kill all the fun, blame dust for Betelgeuse’s dimming – Internal convection and a regular cycle combine to make a big blob of dust.” [ https://arstechnica.com/science/2020/08/astronomers-kill-all-the-fun-blame-dust-for-betelgeuses-dimming/ ] It’s all about the click bait in this case, since it isn’t an imminent or close supernova (~1 klyrs is 1 % of the Milky Way diameter – such supernova has happened many times before).

      The estimated remaining lifetime of Betelgeuze is, according to Wikipedia, 100 kyrs. Without further information on the models that go into the estimate, the best we can do is to say that there is a 10^-5 risk that it go supernova any given year. As a rough equality comparison, that is about half the death risk that a US pedestrian takes going outside.

      As for consequences on Earth, Betelgeuse is a core collapse supernova candidate, meaning it is classified as a type II supernova. Citing Wikipedia again: “Recent estimates predict that a Type II supernova would have to be closer than eight parsecs (26 light-years) to destroy half of the Earth’s ozone layer, and there are no such candidates closer than about 500 light years.[150]”

    • Étienne Brodeur | August 15, 2020 at 9:53 am | Reply

      James, the word supernova was the clickbait. They don’t have anymore information than the scientists. The fact is that we don’t have a clue.

      We all clicked to see if there was additional information on this site compared to say nasa.gov or space.com.

    • In astronomical terms, imminent usually means “sometime in the next 10,000 to 50,000 years”

  2. 700 plus light years away? I think we are good as far as radiation exposure goes. We’re doing fine with radiating our planet by ourselves

  3. Tired of tired | August 15, 2020 at 9:34 am | Reply

    I wouldn’t want the betelgeuse to disappear, so how could Orion go hunting without one arm?
    The whole sky wouldn’t make sense then.

    • Torbjörn Larsson | August 15, 2020 at 9:57 am | Reply

      There is a 1/10 risk that Betelgeuse goes supernova within 10 kyrs, which is roughly the time the current star patterns makes sense (c.f. how astrology of half that time is already not mapping well to the current sky patterns).

  4. >”…the dimming would have happened around the year 1300.”

    The most awesome statement in the article, IMHO. We are approximately 7.5 centuries behind the times in recent news from Betelgeuse. We are so small and constrained by human perception.

    Whatever comes “next” will have happened a long, long time ago. Around the time of the founding of the Ottoman empire, around the time of the bubonic plague, prior to the Renaissance.

    • These are my thoughts exactly! And 700 years from now, when people look toward Betelgeuse, they will be looking back to what’s actually happening NOW.

  5. Quick answer: Not in our lifetime, folks.

  6. Solar and Terrestrial Relations Observatory,
    DOES NOT SPELL STEREO!

  7. David Cameron | August 16, 2020 at 4:37 am | Reply

    I watched someone on the discovery channel say Betelgeuse is running out of fuel and could go supernova at anytime , She said when she looks at Betelgeuse she always hopes it will happen in her life time , I think I remember this correctly.

  8. This behavior by Betelgeuse is not new. It was first documented a century ago, in the year 1920, by astronomers. This is not news, it is simply astronomy. If you enjoy astronomy, get used to headlines being written about the latest observations. When I saw the headlines and photographs in the newspaper, when Voyager took the first close up pictures of the rings of Saturn, I showed it to a fellow university student. She said, “oh, I only have a certain amount of time for things in my life, and I do not have time for Saturn.”

  9. Define imminent.

  10. sure looks like a starfart to me!

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