Betelgeuse, the closest red giant star to Earth, is exhibiting unusual behavior. Normally, the star cycles between bright and dim states every 400 days. However, between late 2019 and early 2020, it went through a "great dimming" due to a dust cloud that obscured our view of the star. Currently, Betelgeuse is glowing at 150% of its normal brightness and is cycling between bright and dim states every 200 days, which is twice as fast as usual, making it the seventh brightest star in the night sky.
The great dimming was caused by a surface mass ejection of gas and dust, a phenomenon resulting from an anomalously hot convective plume. This ejection, which was several times the mass of Earth's moon, has caused changes in the star's forces and stability.
“If we were to throw one of our arms away from us, it changes the way our forces move in our body. And a similar thing happened with poor Betelguese,” says Webb.
Betelgeuse is anticipated to explode as a supernova in the next 10,000 to 100,000 years.
> Betelgeuse is anticipated to explode as a supernova in the next 10,000 to 100,000 years.
I would like Theguardian to expose a standard deviation for this kind of data (because I have read from other sources that nobody has the data, it easily may be tomorrow).
I don't think any natural law would be broken if it goes off 10-100,000 years before "schedule".
It's 10M years old after all, nobody would mind if it happens sooner :)
When it explodes, Betelgeuse is expected to be brighter than the full moon. Gamma ray bursts appear to follow the axis of rotation of the star, and since that axis does not point directly at Earth (it is off by about 20 degrees), that's not a threat. So it will be exciting, scary and safe - like a rollercoaster that everyone on Earth gets to ride at the same time.
If it does I hope people will look to the stars more and reflect on their beautiful place in the universe. I can hardly envision a more navel gazing species than humans, and we need more people with telescopes and wide views.
> If you ever find yourself in die company of a fundamentalist, much pleasant argumentation can result if you ask him or her a simple question: Did Adam and Eve have bellybuttons?
> For those who believe the Bible to be historically accurate, this is not a trivial question. If Adam and Eve did not have navels, then they were not perfect human beings. On die other hand, if they had navels, then the navels would imply a birth they never experienced.
> But our first parents, Adam and Eve, didn't develop that way. I believe that God would not have planted on them a false indication that they had developed in a mother's womb.
Ah. About that "gamma bursts appear to follow the spin axis" rule - do Earth's astronomers have good data, with a comfortable n, to justify confidence that their little planet can't possibly get toasted by this rather large and unstable stellar neighbor?
How did that turn out? Were they acquitted? I've noticed in other cases that Italian prosecutors seem have an unusual amount of latitude, or is that normal?
Wait a minute. If you emit material wouldn't you spin slower. Take the arm waving example from the article.
Stand in the middle of the room and spin with you arms at your side. Now suddenly spread you arms. You will notice a marked reduction in rotation speed, not an increase.
Imagine instead that you’re sitting on a swivel chair and you fire a gun with your right hand. This is more akin to how ejection of materials work. When you put your hands out on the swivel chair, the hands are still attached and are forced into orbit around your torso, when you eject material this isn’t the case, and it leaves the system.
In that example, your arms are still rotating about an axis. The moment of inertia of the rotating body increases, so the angular velocity decreases. Imagine instead that the ejected material is no longer rotating about an axis (say, you detached your arms and flung them away in a straight line); the moment of inertia of the remaining rotating body _decreases_, so the angular velocity increases.
This doesn't (necessarily) have anything to do with rotation speed, and the article doesn't say it does. The fact that Betelgeuse is pulsating more quickly does not imply that it is rotating more quickly.
Making an entire star suddenly spin twice as fast on its axis would require a staggeringly, absurdly huge transfer of energy and angular momentum. The mass ejected from Betelgeuse was much, much smaller than the star's total mass, and would not have been capable of causing such an effect.
I don't think the pulsations are due to rotation. It grows and shrinks periodically, causing changes in absolute magnitude; and there seems to be more than one period. The various periods seem to be related harmonically.
"Evidence for a large cool spot: What could lead to a temperature drop by 170 K? It should be noted that the lowest temperature obtained on 31-01-2020, Teff = 3476 K, would be one of the coolest effective temperatures measured for a Galactic RSG... According to the stellar evolution theory, the Hayashi limit (the lower limit of Teff for stars in hydrostatic equilibrium) for a star like Betelgeuse is ∼3500 K (see, e.g., Figure 6.5 in 16). Nevertheless, the significance of the Hayashi limit for RSGs is still open to debate. It has been suggested that the stars moved to the forbidden region of the Hertzsprung-Russell (H-R) diagram are not able to maintain their hydrostatic equilibrium and this may actually drive episodes of enhanced mass loss."
It seems could have broken the Hayashi limit that describes a star's lowest possible surface temperature at a given mass or radius for Red Super Giants.
In those cases it seems either:
- Would go Supernova
- Would have mass loss that would cause the star to shrink back within the Hayashi limit. So no Supernova for you...
>There are records from ancient Egypt of what appears to be a star exploding as a supernova. The Egyptians described the appearance of a “second sun” in the sky, says Webb.
That statement interests me, I did a search and the closest thing I found was SN 1006:
But that did not come close to the brightness of the Sun and it happened a bit over 1000 years ago. To me, ancient Egypt refers to well over 2000 years ago.
Are you looking back far enough? Ancient Egypt really fucking ancient. Like it was about as ancient to classical antiquity as classical antiquity is to us now.
Cleopatra was part of the Macedonian/Greek dynasty in Egypt, which comes basically at the tail end of what one might consider "ancient Egypt". The time span we lump together as "ancient Egypt" (specifically, dynastic ancient Egypt—"pre-dynastic" stretches back many centuries before that) is so long that stuff from the first third or so of it is farther, time-wise, from Cleopatra than the moon landings were.
Wikipedia:
> All [the three big pyramids at Giza] were built during the Fourth Dynasty of the Old Kingdom of ancient Egypt, between 2600 and 2500 BC.
Cleopatra is tied up with Julius Caesar and Antony (as in Shakespeare's Antony and Cleopatra) and all that happens just before the BC/AD transition, and these numbers are large and fuzzy enough we can just call her time 0. ~2500 years after the pyramids, ~1970 before the moon landings. Plus or minus a few years, but it doesn't make much difference.
I remember visiting Lincoln Cathedral and realising that when it was built in 1311 it was the first new tallest building for 3900 years... (160m as opposed to the 147m of the great pyramid) though the spire collapsed 238 years later.
Just to get things back into proportion, Betelgeuse is one of several hundred pulsating red supergiants visible with the unaided eye, binoculars or a small telescope (here are some around the Double Cluster in Perseus: https://www.dritter.net/astronomy/clusters/ngc869-884_03.asp...). Many of these are significantly more luminous than Betelgeuse, and it is far more probable (just from the numbers) that one or more of these will turn supernova before Betelgeuse does. The recent fade and subsequent brightening of Betelgeuse are fairly typical behaviour for pulsating red supergiants, and are probably not relevant to whether it is about to turn supernova or not.
80 comments
[ 3.3 ms ] story [ 161 ms ] threadBetelgeuse, the closest red giant star to Earth, is exhibiting unusual behavior. Normally, the star cycles between bright and dim states every 400 days. However, between late 2019 and early 2020, it went through a "great dimming" due to a dust cloud that obscured our view of the star. Currently, Betelgeuse is glowing at 150% of its normal brightness and is cycling between bright and dim states every 200 days, which is twice as fast as usual, making it the seventh brightest star in the night sky.
The great dimming was caused by a surface mass ejection of gas and dust, a phenomenon resulting from an anomalously hot convective plume. This ejection, which was several times the mass of Earth's moon, has caused changes in the star's forces and stability.
“If we were to throw one of our arms away from us, it changes the way our forces move in our body. And a similar thing happened with poor Betelguese,” says Webb.
Betelgeuse is anticipated to explode as a supernova in the next 10,000 to 100,000 years.
I would like Theguardian to expose a standard deviation for this kind of data (because I have read from other sources that nobody has the data, it easily may be tomorrow).
Tomorrow is in the next 10,000 to 100,000 years.
Too long. Speed it up.
Space is big.
http://www.wolframalpha.com/input/?i=size%20Betelgeuse%2Fsiz...
It strains intuition that this would even be observable, it's such a tiny fraction of the total mass of the star.
As in "just before it pops, the undulations are {such-and-such} for 1 month"
[1] https://sites.uni.edu/morgans/astro/course/TheStar.pdf
https://en.wikipedia.org/wiki/Comet_Shoemaker%E2%80%93Levy_9
> If you ever find yourself in die company of a fundamentalist, much pleasant argumentation can result if you ask him or her a simple question: Did Adam and Eve have bellybuttons?
> For those who believe the Bible to be historically accurate, this is not a trivial question. If Adam and Eve did not have navels, then they were not perfect human beings. On die other hand, if they had navels, then the navels would imply a birth they never experienced.
https://cdn.centerforinquiry.org/wp-content/uploads/sites/29...
> But our first parents, Adam and Eve, didn't develop that way. I believe that God would not have planted on them a false indication that they had developed in a mother's womb.
https://AnswersInGenesis.org/adam-and-eve/did-adam-have-a-be...
Asking for a friend.
"Italian scientists convicted for not warning about deadly 2009 quake"
https://www.cbsnews.com/news/italian-scientists-convicted-fo...
I have a new saying!
Stand in the middle of the room and spin with you arms at your side. Now suddenly spread you arms. You will notice a marked reduction in rotation speed, not an increase.
Who can explain this for me?
Making an entire star suddenly spin twice as fast on its axis would require a staggeringly, absurdly huge transfer of energy and angular momentum. The mass ejected from Betelgeuse was much, much smaller than the star's total mass, and would not have been capable of causing such an effect.
Sort of like that.
"Evidence for a large cool spot: What could lead to a temperature drop by 170 K? It should be noted that the lowest temperature obtained on 31-01-2020, Teff = 3476 K, would be one of the coolest effective temperatures measured for a Galactic RSG... According to the stellar evolution theory, the Hayashi limit (the lower limit of Teff for stars in hydrostatic equilibrium) for a star like Betelgeuse is ∼3500 K (see, e.g., Figure 6.5 in 16). Nevertheless, the significance of the Hayashi limit for RSGs is still open to debate. It has been suggested that the stars moved to the forbidden region of the Hertzsprung-Russell (H-R) diagram are not able to maintain their hydrostatic equilibrium and this may actually drive episodes of enhanced mass loss."
It seems could have broken the Hayashi limit that describes a star's lowest possible surface temperature at a given mass or radius for Red Super Giants.
In those cases it seems either:
- Would go Supernova
- Would have mass loss that would cause the star to shrink back within the Hayashi limit. So no Supernova for you...
See "25.1 Main characteristics of massive star evolution" on this one: "Understanding Stellar Evolution" - https://www.hennylamers.nl/wp/wp-content/uploads/2014/10/Lam...
"Hayashi limit" - https://en.wikipedia.org/wiki/Hayashi_limit
That statement interests me, I did a search and the closest thing I found was SN 1006:
https://en.wikipedia.org/wiki/SN_1006
But that did not come close to the brightness of the Sun and it happened a bit over 1000 years ago. To me, ancient Egypt refers to well over 2000 years ago.
So wondering if that statement is really true.
Cleopatra was part of the Macedonian/Greek dynasty in Egypt, which comes basically at the tail end of what one might consider "ancient Egypt". The time span we lump together as "ancient Egypt" (specifically, dynastic ancient Egypt—"pre-dynastic" stretches back many centuries before that) is so long that stuff from the first third or so of it is farther, time-wise, from Cleopatra than the moon landings were.
Wikipedia:
> All [the three big pyramids at Giza] were built during the Fourth Dynasty of the Old Kingdom of ancient Egypt, between 2600 and 2500 BC.
Cleopatra is tied up with Julius Caesar and Antony (as in Shakespeare's Antony and Cleopatra) and all that happens just before the BC/AD transition, and these numbers are large and fuzzy enough we can just call her time 0. ~2500 years after the pyramids, ~1970 before the moon landings. Plus or minus a few years, but it doesn't make much difference.
1.https://en.wikipedia.org/wiki/Wrangel_Island#First_human_set...
"The known history of supernova observation goes back to 1006 CE. All earlier proposals for supernova observations are speculations with many alternatives. " -- https://en.wikipedia.org/wiki/History_of_supernova_observati...
There's a rock drawing in Kashmir, India of what might be a supernova (HB9) dating to -4600BCE ...
https://www.theguardian.com/world/2018/jan/10/two-suns-no-it...