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Fri Feb 14, 2020, 11:24 PM

Dimming of supergiant star Betelgeuse more likely due to dust than imminent explosion, ESO says



Images of the red supergiant Betelgeuse taken with the ESO's Very Large Telescope in January 2019 and in December, when it had lost much of its brightness. | AFP-JIJI

AFP-JIJI
FEB 15, 2020

PARIS – Astronomers have managed to take pictures of Betelgeuse showing that the star, one of the brightest in the Milky Way, has been losing luminosity over recent months, the European Southern Observatory said on Friday.

The mysterious dimming of one of the most visible stars in the constellation Orion has astronomers scratching their heads, with some saying Betelgeuse could be about to explode, while others point to passing conditions.

“The stunning new images of the star’s surface show not only the fading red supergiant but also how its apparent shape is changing,” the ESO said after astronomers used the observatory’s Very Large Telescope to find out more.

A team led by Miguel Montarges, astronomer at KU Leuven university in Belgium, has been observing the star with ESO’s VLT since December, aiming to understand why it is becoming fainter.

More:
https://www.japantimes.co.jp/news/2020/02/15/world/science-health-world/dimming-supergiant-star-betelgeuse-likely-due-dust-imminent-explosion-eso-says/#.Xkdxz2hKjDc

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Reply Dimming of supergiant star Betelgeuse more likely due to dust than imminent explosion, ESO says (Original post)
Judi Lynn Friday OP
RockRaven Friday #1
Warpy Saturday #2
localroger Saturday #3
Igel Sunday #5
SCantiGOP Saturday #4

Response to Judi Lynn (Original post)

Fri Feb 14, 2020, 11:31 PM

1. In some ways that's a bummer. It would be a hell of a thing to have the dumb luck to be alive

when an already-well-known star has a cataclysmic event, never mind in a time such as ours with so many incredible instruments which could be brought to bear.

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Response to Judi Lynn (Original post)

Sat Feb 15, 2020, 02:41 AM

2. That was my guess, but if that thing is belching out its outer layers

in clouds of gas and dust and causing the dimming, that could also signal an explosion sooner rather than later.

All we really know is that we don't really know. Most of these things happen so far away that we haven't been able to watch them beforehand to see what they're doing even on a month to month basis before they blow.

Betelgeuse could have a hundred thousand more year of puffing up, blowing off dust, and contracting before it goes.

Theory says that as soon as a giant star starts to produce iron in its core, it's all over. Betelgeuse is putting that theory to the test, which is why astronomers keep hoping it blows soon.

Meaning, of course, tomorrow 330-650 years ago.

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Response to Warpy (Reply #2)

Sat Feb 15, 2020, 08:32 AM

3. Where's the neutrino observatories on this?

Fun fact: It normally takes thousands of years for electromagnetic radiation to make it from the core of a star to its photosphere so we can see it, so you can't tell from its spectrum that it's burning something other than hydrogen to hold itself up. But you CAN tell from the neutrinos, which fly right out. We have neutrino observatories which use photodetectors in huge tanks of water to look for the rare interactions when a neutrino does bother to interact with a nucleus, and this is a regular part of solar astronomy nowadays. I recall reading that we actually detected a few neutrinos from other supernovae at much greater distances than Betelgeuse, so I would think that if the big guy was burning heavy elements those neutrino tanks would give us our first clue.

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Response to localroger (Reply #3)

Sun Feb 16, 2020, 11:41 AM

5. True, but big stars burn through the layers

with some heavy elements so fast.

One prediction is that the last layer to go, when only silicon is left to burn, will take perhaps a day for the entire star. Less heavy elements will take months, even lighter will take years or thousands of years.

Then there's only really iron left and the internal volume's reduced (after all, 1 Si nucleus doesn't take up the same room as a couple dozen He++ , radiation pressure doesn't hold back weight, what's left, and you get a core-collapse supernova.

Predictions are that we should get warning that the silicon's burning, about a 24 hour notice. We might get sufficient word that the precursors are "on the barbie". Problem is, the signal's going to be robust statistically (in hindsight) but might be missed in real time.

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Response to Judi Lynn (Original post)

Sat Feb 15, 2020, 06:37 PM

4. You just ruined my day

I was looking forward to seeing an object in the sky brighter than Venus.

And, since most repubs don't believe in science, they might all evacuate to their Jim Bakker-stocked underground shelters because of the demonic signs in the heavens

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