That image looks almost like Betelgeuse is being eclipsed…by something around as big as the star itself.
What evidence do we have that the star is in the middle of a solar system full of debris like nebular gas and dust?
There are photographs of Halley’s in 1910, and man, it was something to behold. Even accounting for the use of long exposure, it was huge. (Artists’ renditions are often very, very similar, too, suggesting a degree of illustrative honesty.) You are certainly right in that it was a lot easier to appreciate its full glory back when there was like one-hundredth as much urban light, but if you could, it was spectacular. The 1910 approach was very close even by its standards; its looking awesome was predictable.
I think at this point we can probably rule out the starspot explanation. I don’t think it’s possible for starspots to cover that large a percentage of the surface, or at least, anything that does cover that large an area operates on sufficiently different principles from the starspots we know that it should be called by a different name.
That image certainly looks consistent with the dust cloud hypothesis.
The ESO picture seems to show a lot of dust in the region around Betelgeuse. I think occluding dust cloud is the most likely hypothesis right now.
You are indeed great sages @Chronos and @Sam_Stone :
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.
Hubble researchers suggest that the dust cloud formed when superhot plasma unleashed from an upwelling of a large convection cell on the star’s surface passed through the hot atmosphere to the colder outer layers, where it cooled and formed dust grains. The resulting dust cloud blocked light from about a quarter of the star’s surface, beginning in late 2019. By April 2020, the star returned to normal brightness.
A little more data here: Hubble finds that Betelgeuse's mysterious dimming is due to a traumatic outburst
That’s always been a possibility, but it’s looking a lot less likely now that it’s both been explained and returned to its normal brightness.
Which post are you replying to?
A post which got nuked, saying that it was probably a sign of imminent supernova. The post itself was innocuous enough, but apparently the same poster went on to spam somewhere else. Spammers will do that sometimes, making a few innocuous posts before delivering their payload, to try to avoid detection.
Bad Astronomy:
Don’t panic! But Betelgeuse may be 25% closer to Earth than we previously thought
530 vs. 640 light years. Still no threat if it explodes, and apparently new data shows that that won’t happen for over a million years anyway.
Yeah right.
I’m not believing anything that star says ever again.
Some further updates:
Our Sun routinely blows off parts of its tenuous outer atmosphere, the corona, in an event known as a Coronal Mass Ejection (CME). But the Betelgeuse SME blasted off 400 billion times as much mass as a typical CME!
The monster star is still slowly recovering from this catastrophic upheaval. “Betelgeuse continues doing some very unusual things right now; the interior is sort of bouncing,” said Andrea Dupree of the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts.
These new observations yield clues as to how red stars lose mass late in their lives as their nuclear fusion furnaces burn out, before exploding as supernovae. The amount of mass loss significantly affects their fate. However, Betelgeuse’s surprisingly petulant behavior is not evidence the star is about to blow up anytime soon. So the mass loss event is not necessarily the signal of an imminent explosion.
Dupree is now pulling together all the puzzle pieces of the star’s petulant behavior before, after, and during the eruption into a coherent story of a never-before-seen titanic convulsion in an aging star.
Which was a summary of this article:
I wonder if this CME, which in photographs appears to be about 1/4 the diameter of the star itself, might have blown enough mass off Betelgeuse to make a supernova unlikely?
Keep in mind that Betelgeuse is, IIRC, big enough that were it to replace our sun, it would swallow up all the planets to Jupiter.
Nah. CMEs are massive compared to the usual stellar wind, but compared to the mass of the entire star, they’re virtually nothing. Even a very large one is not going be a significant amount of mass.
Yes, but 99.99+% of that diameter is a gas so thin we’d consider it a decent vacuum on Earth.
And now I’m wondering when Webb will look at Betelgeuse. If I’m not mistaken, it should be orbiting into a position where it can see it pretty soon, now, and it seems like the perfect tool for the job.
It probably won’t tell us anything fundamental that we don’t already know or strongly suspect, but there’s a lot of good data in the fine details.
Who uses the term “petulant behavior” to describe a star … twice? It’s not like we’re going to send Betelgeuse to its room without its dinner.
The density of the gas at the surface of the local sun is only about 1/4000 the density of normal atmosphere on Earth, but that does not mean you would want to sit at the surface of the sun (or deeper!)
As for Betelgeuse, the temperature of the plasma at the distance of Jupiter (or even Uranus) is going to be pretty hot; anybody have a quick link to the latest data so we can figure out exactly what you would be exposed to?
The issue at hand in my post was whether a CME would change the evolution of the star towards a supernova. To do that, the amount of mass of the star is the important variable, not its temperature. So I was pointing out that there’s really very little mass in the atmosphere of a supergiant compared with the mass of the star as a whole.
That’s easy: It’s red hot. And therefore at the same temperature as anything else in the Universe that’s red hot. Well, OK, that’s a range of temperature, because there are different shades of red, but good enough for our purposes.
Wikipedia says Betelgeuse is about 3600 +/- 200 K. That’s roughly the temperature of the filament of a 60-watt incandescent light bulb. As I understand it, the recent loss of brightness is due to dust in between the star and us, so it’s still that temperature.