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Oh, Betelgeuse, everyone’s favorite M2Iab supergiant star. Why did it dim so catastrophically earlier this year?
Hubble may have clinched the answer: It erupted, blowing out a HUGE dust cloud that blocked its light. https://www.syfy.com/syfywire/smoking-gun-at-betelgeuse-hubble-shows-it-was-belching-dust-that-dimmed-the-red-supergiant
Hubble may have clinched the answer: It erupted, blowing out a HUGE dust cloud that blocked its light. https://www.syfy.com/syfywire/smoking-gun-at-betelgeuse-hubble-shows-it-was-belching-dust-that-dimmed-the-red-supergiant
Always looking for a hook by anthropomorphization, which Betelgeusian dust-cloud-exuding bodily expulsion metaphor works best for you?
3/ It wasn't clear why Betelgeuse got so faint that you could just go outside and look at it to see how dim it had gotten. It dropped in brightness by 70%! One idea was starspots, like sunspots but on other stars, and the other was it blasting out a dust cloud.
4/ So what's new here? Hubble observations in the ultraviolet showed that the supergiant star got *brighter* in the UV just before The Great Dimming. That can happen when a big pulse, like a wave, moves up from deep inside the star, compressing the upper layers and heating them.
5/ Once it got near the surface the material cooled, forming dust (teeny rocky or sooty grains), which then blasted away in a cloud. That stuff is opaque, so it blocked the light from Betelgeuse, dimming it. That explains why it got brighter first, then dimmer.
6/ But there's more! Pix taken in early and late 2019 by the Very Large Telescope showed that just the southern half of Betelgeuse dimmed. So whatever happened was local. It didn't happen over the whole star. [Note: This is AN ACTUAL IMAGE of Betelgeuse!]
https://www.syfy.com/syfywire/betelgeuses-shenanigans-just-got-weirder-only-part-of-it-is-dimming
![6/ But there's more! Pix taken in early and late 2019 by the Very Large Telescope showed that just the southern half of Betelgeuse dimmed. So whatever happened was local. It didn't happen over the whole star. [Note: This is AN ACTUAL IMAGE of Betelgeuse!] https://www.syfy.com/syfywire/betelgeuses-shenanigans-just-got-weirder-only-part-of-it-is-dimming](https://pbs.twimg.com/media/EfY_iBzWkAAcMw2.jpg "6/ But there's more! Pix taken in early and late 2019 by the Very Large Telescope showed that just the southern half of Betelgeuse dimmed. So whatever happened was local. It didn't happen over the whole star. [Note: This is AN ACTUAL IMAGE of Betelgeuse!] https://www.syfy.com/syfywire/betelgeuses-shenanigans-just-got-weirder-only-part-of-it-is-dimming")
https://www.syfy.com/syfywire/betelgeuses-shenanigans-just-got-weirder-only-part-of-it-is-dimming
7/ Hubble's eyesight is so keen, and Betelgeuse so bloated, that the 'scope could look at JUST the southern hemisphere. It found the UV burst came from just there, further supporting the idea of a giant pulse creating the flash and subsequent dust cloud.
8/ IMO this clinches the deal. It's not clear why there was such a big pulse. Betelgeuse does undergo regular pulsations; they're just not usually anywhere near this scale. Maybe a few different things happened inside the star at the same time to amplify the pulse.
9/ And it may do this sort of thing more often than we think; if it happened on the other side of the star we wouldn't see it. As I note in my article, it may be dimming again ahead of schedule (it has been brightening since February). https://www.syfy.com/syfywire/no-supernova-for-you-betelgeuse-is-brightening-again-right-on-schedule
10/ And I have to note, because it tickles me so: The Hubble observations were made with STIS, the Space Telescope Imaging Spectrograph, a camera I worked on for many years before going scicomm full time. https://www.nasa.gov/content/hubble-space-telescope-space-telescope-imaging-spectrograph
11/11 Keep watching the skies! Betelgeuse now rises ahead of the Sun, and astronomers will soon be able to point their 'scopes at this brain-stompingly huge star once again. What will we see when we do? https://www.syfy.com/syfywire/smoking-gun-at-betelgeuse-hubble-shows-it-was-belching-dust-that-dimmed-the-red-supergiant
