B Betelgeuse unusual dimming - what's up?

[Astronuc]

UW, March 6, 2020 - Dimming Betelgeuse likely isn’t cold, just dusty, new study shows
https://www.washington.edu/news/2020/03/06/dimming-betelgeuse-dust/

In a paper accepted to Astrophysical Journal Letters and published on the preprint site arXiv, Emily Levesque, a UW associate professor of astronomy, and Philip Massey, an astronomer with Lowell Observatory, report that observations of Betelgeuse taken Feb. 14 at the Flagstaff, Arizona, observatory allowed them to calculate the average surface temperature of the star. They discovered that Betelgeuse is significantly warmer than expected if the recent dimming were caused by a cooling of the star’s surface.

The new calculations lend support to the theory that Betelgeuse — as many red supergiant stars are prone to do — has likely sloughed off some material from its outer layers.

Betelgeuse Just Isn't That Cool: Effective Temperature Alone Cannot Explain the Recent Dimming of Betelgeuse
https://arxiv.org/abs/2002.10463

 

[zoki85]

I hope it goes Nova in my lifetime. It would be sight to see. My grandmother used to tell me tales about Orion when I was kid.

 

[Vanadium 50]

I hope it goes Nova in my lifetime.

Unless you will live to be 2000, this is unlikely to happen.

 

[zoki85]

Unless you will live to be 2000, this is unlikely to happen.

We hope for the best

 

[Astronuc]

Nature, June 16, 2021 - Great Dimming of Betelgeuse explained
https://www.nature.com/articles/d41586-021-01526-6

Observations suggest that an unexpected dimming of the massive star Betelgeuse resulted from dust forming over a cold patch in the star’s southern hemisphere. This finding improves our understanding of such massive stars.

https://www.sciencenews.org/article/betelgeuse-dust-cold-spell-why-giant-star-dimmed

But it seems this is old news -
Hubble Finds That Betelgeuse's Mysterious Dimming Is Due to a Traumatic Outburst
https://www.nasa.gov/feature/goddar...erious-dimming-is-due-to-a-traumatic-outburst

Observations by NASA's Hubble Space Telescope are showing that the unexpected dimming of the supergiant star Betelgeuse was most likely caused by an immense amount of hot material ejected into space, forming a dust cloud that blocked starlight coming from Betelgeuse's surface.

 

[Orodruin]

Nature, June 16, 2021 - Great Dimming of Betelgeuse explained
https://www.nature.com/articles/d41586-021-01526-6

https://www.sciencenews.org/article/betelgeuse-dust-cold-spell-why-giant-star-dimmed

But it seems this is old news -
Hubble Finds That Betelgeuse's Mysterious Dimming Is Due to a Traumatic Outburst
https://www.nasa.gov/feature/goddar...erious-dimming-is-due-to-a-traumatic-outburst

Funny. I was just searching for this thread to post this.

 

[epenguin]

The Times last Thursday reported:

"The “great dimming” of Betelgeuse can be attributed to the sudden formation of an opaque veil of stardust...

images captured by the European Southern Observatory’s Very Large Telescope, which is in the Atacama Desert of northern Chile, together with earlier pictures to show how the surface of the star was changing, particularly its southern region. The surface of Betelgeuse, which is about 643 light years from Earth, alters as vast bubbles of gas move, shrink and swell within the star. The scientists have concluded that some time before the great dimming, the star ejected a large gas bubble. When a patch of its surface cooled shortly afterwards, the temperature decrease was enough for heavier elements, such as silicon, that were contained within the gas to condense into solid particles.

...Andrea Dupree... discovered signs of dense, heated material moving through the star’s atmosphere in the months leading up to the great dimming... With Hubble, we could see the material as it left the star’s surface and moved out through the atmosphere, before the dust formed that caused the star to appear to dim,” Dupree said.

Once the gas bubble was millions of miles from the hot star, it cooled and formed a dust cloud. Betelgeuse returned to its normal brightness by April last year."

https://www.thetimes.co.uk/article/stardust-solves-puzzle-red-giant-betelgeuse-explained-v6mdnd3d8

 

[Orodruin]

The Times last Thursday reported:

"The “great dimming” of Betelgeuse can be attributed to the sudden formation of an opaque veil of stardust...

images captured by the European Southern Observatory’s Very Large Telescope, which is in the Atacama Desert of northern Chile, together with earlier pictures to show how the surface of the star was changing, particularly its southern region. The surface of Betelgeuse, which is about 643 light years from Earth, alters as vast bubbles of gas move, shrink and swell within the star. The scientists have concluded that some time before the great dimming, the star ejected a large gas bubble. When a patch of its surface cooled shortly afterwards, the temperature decrease was enough for heavier elements, such as silicon, that were contained within the gas to condense into solid particles.

...Andrea Dupree... discovered signs of dense, heated material moving through the star’s atmosphere in the months leading up to the great dimming... With Hubble, we could see the material as it left the star’s surface and moved out through the atmosphere, before the dust formed that caused the star to appear to dim,” Dupree said.

Once the gas bubble was millions of miles from the hot star, it cooled and formed a dust cloud. Betelgeuse returned to its normal brightness by April last year."

https://www.thetimes.co.uk/article/stardust-solves-puzzle-red-giant-betelgeuse-explained-v6mdnd3d8

Isn’t this just a popularized account of what was already posted in #55?

 

[DaveC426913]

When a patch of its surface cooled shortly afterwards, the temperature decrease was enough for heavier elements, such as silicon, that were contained within the gas to condense into solid particles.

So we're sayin' ... it snowed.
Silicon.
On a star.

 

[sophiecentaur]

So we're sayin' ... it snowed.
Silicon.
On a star.

Well, why not? It's a funny old world out there and it seems that almost anything goes, if you look hard enough for it.

 

[Astronuc]

The scientists have concluded that some time before the great dimming, the star ejected a large gas bubble. When a patch of its surface cooled shortly afterwards, the temperature decrease was enough for heavier elements, such as silicon, that were contained within the gas to condense into solid particles.

This is an interesting piece that's not mentioned in other published summaries. I take the part about "before the great dimming, the star ejected a large gas bubble" to mean something like a CME, but it was still hot and transparent. Then "when a patch of its surface cooled shortly afterwards, the temperature decrease was enough for heavier elements, such as silicon, that were contained within the gas to condense into solid particles." But isn't it the ejected mass that cooled? Or did the outer surface cool?

In either event, cooling such that Si or perhaps SiO₂ precipitated and condensed into dust particles, and perhaps Al₂O₃, or alumina-silicates.

There is this paper "A dusty veil shading Betelgeuse during its Great Dimming"
https://www.nature.com/articles/s41586-021-03546-8