
ESO telescope sees surface of dim Betelgeuse - dnetesn
https://phys.org/news/2020-02-eso-telescope-surface-dim-betelgeuse.html
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SiempreViernes
The original ESO press release is probably a better link, as the phys.org text
mostly just a small bit of context but doesn't include the "before" pictures
or links to any further details.

[https://www.eso.org/public/news/eso2003/](https://www.eso.org/public/news/eso2003/)

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Defenestresque
Thanks! I was very curious about the before/after comparison but didn't see a
working link in the original article.

Here is the direct YT link (from your article):
[https://youtu.be/o1ls7Gr9LTE](https://youtu.be/o1ls7Gr9LTE)

This truly seems like a completely massive change in the observable
characteristics of the star especially on such a short timeframe. 36% dimmer
in 12 months? I'll be really interested to see if we can find out for sure
what's happening.

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tigershark
No, 36% of its normal brightness, so it’s about 1/3 as bright as usual.

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retro64
Orion is one of my favorite constellations. Where I grew up, the winter sky
was often clear and I spent many hours as a youth gazing up, wondering about
it all.

Even now, when I saw a pic of Orion after following links from the article, I
again couldn’t help but think about how awesome the universe is, and how
whatever is going on out there just dwarfs our petty, shitty little Earthy
problems.

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brandmeyer
If you ever get the chance to look up at the night sky with night-vision
goggles, you should take another look. Its a whole new kind of stunning when
you can clearly see Barnard's loop as well.

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joquarky
Also if you can find a dark enough sky to see the Milky Way with your naked
eyes, it can be quite amazing to directly perceive our physical location in
the galaxy.

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BurningFrog
OK, that picture looks more like there is a gas cloud blocking the view than
that the star itself is fading. Since it's asymmetrical.

BTW, Betelgeuse is more known as Orion's left shoulder.

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jackfoxy
Betelgeuse is really huge, comparable to the size of the orbit of Jupiter. I'm
not an astrophysicist. It seems like that size would make surface asymmetries
more likely.

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shadowgovt
Size and perspective matter; a smaller object much closer to us could occlude
Betelgeuse.

Granted, that object would likely need to be both dark and travelling through
interstellar space, two things that would by themselves be noteworthy. Unless
it's something much, much closer and in the orbit of our own star... I wonder
if they're ruled out Kuiper Belt objects or comets yet?

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gmueckl
This dimming has been going on for a long time now. If an object within our
solar system were to occlude that star, that wiuld only last a few minutes max
before it exits the narrow line of sight again. Keppler's law ensures that. I
would also assume that a gas cloud in interstellar space would be too
homogeneous to occlude one part of a star much more than the rest.

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shadowgovt
I agree on the gas cloud estimate, which leaves us with exotic large
extrasolar bodies if the star isn't actually changing shape (which IIUC, it
also shouldn't be doing...)

Curiouser and curiouser.

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adrianN
Somebody is getting close to completing their Dyson sphere?

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lawlessone
This is probably the last star you would want your Dyson sphere on.

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speakeron
Could be a one-shot Dyson Sphere designed to capture the energy of a
supernova. Like an advanced civilization's version of a nuclear explosion-
pumped X-ray laser[1]

[1]
[https://en.wikipedia.org/wiki/X-ray_laser](https://en.wikipedia.org/wiki/X-ray_laser)

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adrianN
I think if you're at that level of technology you'd rather make sure that the
star doesn't explode and eject a bunch of valuable fuel into deep space.

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bloopernova
That would be an interesting thought exercise for brains better than mine: if
you are a civilization capable of building a physical barrier around an entire
stellar system, what is the best way to generate energy?

I wonder if it would be something to do with neutron stars or magnetars?

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adrianN
The best way I know is creating small artificial black holes, feeding them
matter at just the right rate and harvesting the Hawking radiation. That's
actually _a lot_ easier than building a Dyson sphere.

[https://arxiv.org/abs/0908.1803](https://arxiv.org/abs/0908.1803)

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SiempreViernes
Impressive that they managed to resolve the surface with just adaptive optics,
and that they didn't require a fulll optical interferometry measurement.

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bkloppenborg
Betelgeuse is ~47 milliarcseconds in diameter, making it one of the largest
stars (in angular diameter terms) observable from Earth. It was first resolved
using the Michelson Stellar Interferometer (which had a diameter of 20 meters)
in the 1880s.

I don't know the observational wavelength for the images in the article (VLT-
SPHERE has filters that go from ~1-2 microns), but if the image were in H-band
(1.6 micron wavelength) the resolution of the 8.2 meter telescope is ~49
milliarcsecond, putting this image just at the formal resolution limit. Still,
quite impressive stuff.

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SiempreViernes
Man, I don't know how to feel about this information: resolved imaging of
stellar disks is from the 1880??!

So from the list on wikipedia, I guess they could just do that one star, and
didn't learn very much beyond the radius?

What's the hottest results in the field of spatially resolved stellar
observations?

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jconnop
The measurement was apparently made in 1920, not 1880s. Still surprising.

[https://en.wikipedia.org/wiki/Michelson_stellar_interferomet...](https://en.wikipedia.org/wiki/Michelson_stellar_interferometer)

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yazr
> Over their lifetimes, red supergiants like Betelgeuse create and eject vast
> amounts of material

What % of material is then captured by other forming/formed stars? Doesnt it
just end up in interstellar space ?

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Aperocky
Stars are formed in compressed interstellar matter, so in that sense, given
enough time, a very significant portion will end up in next stars

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onetimemanytime
When it explodes, is it close enough to any damage to us?

Maybe, not destroy life or anything, but increase radiation or something else
harmful. In other words, should we start running ;) ?

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mellosouls
No.

[https://www.discovermagazine.com/the-sciences/what-will-a-
be...](https://www.discovermagazine.com/the-sciences/what-will-a-betelgeuse-
supernova-look-like-from-earth)

 _There’s no need to worry about the stellar explosion. A supernova has to
happen extremely close to Earth for the radiation to harm life — perhaps as
little as several dozen light-years, according to some estimates. Betelgeuse
is far outside that range, with recent studies suggesting it sits roughly 724
light-years away, well outside the danger zone.

But the supernova could still impact Earth in some surprising ways. For
example, Howell points out that many animals use the moon for navigation and
are confused by artificial lights. Adding a second object as bright as the
moon could be disruptive._

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jobseeker990
Which part of Orion is it? One of the shoulders? which?

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oliveshell
It’s Orion’s left shoulder.

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mohaine
It is the star on the left, not necessarily the left shoulder. It is only the
left shoulder if Orion is facing away from you, which I've always assumed he
isn't. Any idea if there is a convention for which direction Orion is facing?

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realreality
If he’s facing us, then his scabbard is on his right side, making him left
handed. Is Orion left handed?

