- #36
mfb
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Betelgeuse is probably too bright for Gaia anyway, but with the right brightness it can measure ~1 km/s. Some stars are variable with a timescale of just hours.
The minimum was 424+-4 days after the previous minimum, perfectly matching the 420-430 day cycles observed before.Based on these and additional observations, Betelgeuse has definitely stopped dimming and has started to slowly brighten.
The article mentions "the red supergiant Betelgeuse has been undergoing an unprecedented decrease in its visual (V) brightness since October 2019." I take that to mean that it is unprecedented since the development of accurate measurements and the recording thereof.mfb said:The Fall and Rise in Brightness of Betelgeuse
The minimum was 424+-4 days after the previous minimum, perfectly matching the 420-430 day cycles observed before.
That makes no sense at all. I don't know what you read (and you didn't tell us) but it was nonsense or you completely misunderstood it.bahamagreen said:The "pop" version suggests ice cores indicating solar variation mapped to the past very distant supernovae show a brief cooling of the Sun followed by a longer warming of the Sun before setting back to normal, these blips effecting the Earth about 100 years later, each instance taking that long to reach the Solar surface from the core... the hook being that the flux and effect from Betelgeuse would be comparatively extremely high... maybe two orders of magnitude.
mfb said:That makes no sense at all. I don't know what you read (and you didn't tell us) but it was nonsense or you completely misunderstood it.
About ~1037 neutrinos would go through the Sun, give or take two orders of magnitude. Less than one in a million of them would interact with anything in the Sun, reactions that change anything (instead of just giving a particle a small kick) would be again orders of magnitude less common.
As comparison: The Sun produces about the same number of neutrinos, 1037, every second. It won't have any impact on the Sun at all.
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.
zoki85 said:I hope it goes Nova in my lifetime.
We hope for the bestVanadium 50 said:Unless you will live to be 2000, this is unlikely to happen.
https://www.sciencenews.org/article/betelgeuse-dust-cold-spell-why-giant-star-dimmedObservations 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.
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.
Funny. I was just searching for this thread to post this.Astronuc said: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
Isn’t this just a popularized account of what was already posted in #55?epenguin said: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
So we're sayin' ... it snowed.epenguin said: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.
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.DaveC426913 said:So we're sayin' ... it snowed.
Silicon.
On a star.
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?epenguin said: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.