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.
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.
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.
It's definitely one of the most identifiable constellations and has several bright stars in the sky: Betelgeuse, Rigel (one of the brightest from Earth) and Bellatrix. The Orion nebula is resolvable with binoculars and easily captured in a DSLR (although it'll be blurry if you don't have tracking).
A newer favorite of mine is Scorpius (visible now at my latitude ~fivein the morning when I walk my dogs); mostly because of Antares, one of the visibly reddest stars in the sky. (And for similar reason, I'm a fan of Aldebaran/Taurus.)
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.
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.
It has always been my guiding constellation along with Karlsvogna (Big Dipper), as it's very often visible in the night sky where I live. Karlsvogna is particularly useful for finding the North Star or Polaris as it's also called and Orion for the meditation over the visible red star on Orions left shoulder (Betelgeuse).
When I emerge myself into space I feel at peace and I can sit by a lake not too far from here for hours watching it and the rest of the stars :)
Orion is one of my favourite constellations too! I had a pretty similar childhood experience. I got photocopies of two star charts (for both hemispheres) off a book I found in my school library and began using the star chart for the northern hemisphere to study the night sky. The winter sky was the best. I was and I still am very fond of the winter sky. I never had to refer to the star chart to locate Orion. It was easily the most recognizable constellation in the winter sky.
Rigel and Betelgeuse, the two brightest stars in Orion are also easily recognizable. They are situated diagonally opposite to each other in the constellation. While Rigel shines bright white, Betelgeuse is distinctly reddish. When I later learnt about red giant stars, the reddish hue of Betelgeuse made even more sense. And then if we imagine a straight line that roughly passes through the three stars in Orion's belt and extend it eastwards, the imaginary line ends up in the vicinity of Sirius, the brightest star of the night sky.
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.
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?
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.
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...)
The asymmetry you are seeing could be a convection zone (the bright spot being the convection zone). There are also theories that the dimming is from expelled matter, and I believe there are telescopes taking measurements to confirm or deny this idea.
An area where hotter matter from the star's interior is convected to the surface, like the granules on the surface of our own sun, but vastly larger. Giant stars, especially near the end of their lives, are weird and unstable and asymmetric and are thought to only have a few huge convection cells covering their whole surface (if you can even talk about a surface given how nebulous giant stars are—almost all of their volume is basically vacuum).
"Jupiter has powerful storms, often accompanied by lightning strikes. The storms are a result of moist convection in the atmosphere connected to the evaporation and condensation of water. They are sites of strong upward motion of the air, which leads to the formation of bright and dense clouds."
...which I read as it is also a convection phenomenon, but due to very different underlying forces, of course. Not that I knew that :)
Yes, and as the WP page says, convection is also what causes thunderstorms on Earth, and, well, pretty much all weather. Convection of solid (but malleable) rock in the mantle is responsible for plate tectonics.
Betelgeuse can not sustain life and it _will_ blow up very soon in cosmic timescales. There is nothing we do to stop it blowing up so yes, I hope to see this event in my lifetime :)
I mean, you're probably correct, but given we have precisely one datapoint for life, it's a bit much to extrapolate further - there might be aeons-old silicon-skinned space whales congregating around Betelgeuse for their thrice giga-millennial spawning season, or something... . Probably not.
- ed
'thrice kilo or mega millennial' seems a bit less unlikely!
Giant stars are quite short-lived, with Betelgeuse estimated to have at most a 15 million (not billion!) year life before becoming a red supergiant . If simple life did evolve in time, it was wiped out about 100,000 years ago as Betelgeuse became a supergiant.
One last fun fact: Betelgeuse is about 125,000 times brighter than the Sun in absolute luminosity.
Well, disregarding radiation resistant space whales (which would be able to migrated to another star anyway), I think it's pretty clear the radiation and onslaught of solar winds from Betelgeuse will sterilise everything in the vicinity.
If we're talking hypotheticals, a tidally locked planet would lose its volatiles pretty quickly, but one could in theory bunker up on the far side of the planet and survive.
But you'd be stuck there forever, right? Diffraction means that the shadow only goes out so far before you're being cooked again by one form of particle or another.
I've started finding this sort of comment very irritating since I've converted to the idea that everything on the surface of a light cone is simultaneous.
The meaning of the so called "relativity of simultaneity" appears to me to be that you just shouldn't talk about simultaneous events with spacelike separation.
If you agree that you can say Betelgeuse is far away without someone objecting with "only in a reference frame that isn't close to it!" then you should also agree that there is an implied set of reference frames that are reasonable to use in the interpretation of comments written on Earth. In the same way that "Betelgeuse is far away" means "Betelgeuse is far away from me," the claim that "an event on Betelgeuse that we are observing today happened in the Middle Ages" means that "an event on Betelgeuse that we are observing today happened in the Middle Ages from a reference frame comoving with anyone on Earth."
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]
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?
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.
If you were next door and you had magic infinitely strong materials, you might want to Dyson-sphere it before it explodes (this dubious concept is found in a number of pieces of science fiction).
Theoretically, you could place a relatively small, dense object fairly close to Betelgeuse and protect your entire stellar neighborhood. I haven't done the math, but I suspect it would have to be so small and dense that it would be a black hole.
You'd probably be better off just trying to shield your planet from whatever lesser energies eventually arrive.
Which makes it the perfect star to cover with a Dyson sphere. What better way to flex on your interstellar neighbors than by harnessing one of the most powerful, violent things in nature?
I think the point being made is the size of it. To make it into a Dyson sphere would require encasing a star that, if centered on Sol, would consume at least the inner 4 planets if not Jupiter as well. It's 950 times the size of our own star and one of the largest in the known universe. There would surely be easier supernova-capturing flexes
"Four intergalactical-capable factions are trying to decide who holds the most power. In an average galaxy in a pretty anonymous corner of the universe one faction detects a unprecedented large star-about-to-go-nova and races to capture the imminent energy surge of a sort the universe hasn't experienced yet. Or will the galaxy implode before they have aligned it all."
A back cover blurb I wouldn't mind picking up! If something like this is already written I want to know.
If I wanted to build Dyson sphere I would choose a star with longer estimated lifetime for bigger bang for the buck. Maybe dwarf star to save on building materials?
Impressive that they managed to resolve the surface with just adaptive optics, and that they didn't require a fulll optical interferometry measurement.
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.
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.
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?
https://www.eso.org/public/news/eso2003/