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  • Betelguese is truly a star.

  • This extremely bright supergiant is famous for its variable fading and brightening

  • and distinctive presence as a red star amongst a sky of twinkling gold.

  • It has secured a name for itself in numerous myths, stories, and recorded observations the world over.

  • But lately, Betelguese has been catching our attention for another reason.

  • Long considered one of the brightest stars in the night sky, it has begun to dramatically fade then brighten again

  • for reasons we can't quite pin down.

  • And it's caused some people to wonder if it's about to explode.

  • Despite being roughly 643 light years away,

  • Betelguese is nearly impossible to miss.

  • For starters, it's MASSIVE; so big that if it were at the center of our Solar System, it would engulf all the planets up to Jupiter.

  • Its diameter is roughly 1,000 times that of our Sun!

  • To find it, just look at the Orion constellation.

  • If Orion isThe Hunterwith his iconic three-star belt, then Betelguese is the hunter's left shoulder.

  • If you're in the Northern Hemisphere during the first few days of January, you can see Betelguese rising in the east just after sunset.

  • All other times, this star is easy to spot no matter where you're located in the world!

  • Especially September through March.

  • Some of the earliest known records of Betelguese come from China in the 1st century BCE.

  • These records describe Betelgeuse as being yellowwhich is strange, because just a few years later, in 150 CE,

  • the Egyptian astronomer Ptolemy described Betelguese as red.

  • This indicates that Betelguse rapidly underwent a stellar phase change sometime between the time these two records were made,

  • evolving to become the red giant that it is today.

  • Betelguese's propensity for fading and brightening over a multi-year cycle also seems to have caught people's attention.

  • In western Aboriginal Australian oral tradition, Betelguese represents the 'fire magic' used by a love-struck hunter to reach the object of his affection.

  • Unfortunately, the fire magic's tendency to flicker out ultimately causes him to fail.

  • While Sir John Herschel continues to be recognized as the first to notice Betelguese's variable brightness,

  • it's clear that people living before the 19th century also recognized what was going on.

  • But recently, Betelguese has us all confused.

  • Typically, its apparent magnitude averages 0.5.

  • That's just how we measure a star's brightness as seen from Earth.

  • That apparent magnitude drops and rises according to short cycles that last a few hundred days,

  • as well as a longer cyclic variation that lasts every 5 years or so.

  • But starting in late 2019, Betelguese began dimming and brightening in a way that was inconsistent with its normal cycles.

  • By mid-February 2020, it had lost more than 2/3rds of its brilliance,

  • becoming the faintest it's been in at least a century!

  • And just a few months later, Betelguese had returned to its normal self.

  • Betelguese is a red supergiant, meaning that it's nearing the end of its life.

  • We know that it's only a matter of time before it explodes as a supernovabut when?

  • That's the mystery.

  • Well, I'm super excited to be talking about this star with you guysbecause it just so happens that I've devoted six years to solving this very question.

  • My research focus is supernovae, so figuring out when Betelguese will explode has been a burning question of mine for quite some time now.

  • I started studying Betelgeuse by running stellar evolution simulations to model how massive stars live and die.

  • By running hundreds of models and comparing them to observations made in the field,

  • my team and I determined that it'll likely be another 100,000 years or so before Betelgeuse explodes as a supernova.

  • So, if it's not going to explode soonwhy is it acting so erratic?

  • Well, there are a few compelling theories.

  • It could be there was a cloud of gas and dust obscuring its light.

  • Massive stars like Betelgeuse undergo violent eruptions as they get older,

  • to the point where they eject matter from their surface.

  • To us, that literally looks like Betelgeuse is burping up shells of matter,

  • which obscure the star from our point of view.

  • Another contributing factor to these violent eruptions are unstable regions within the star.

  • Here, temperature and density wildly fluctuate.

  • All of these characteristics point to the fact that Betelguese is probably still burning helium and is nowhere near the end of its life.

  • Because the fact is, if Betelgeuse were preparing to explode, we'd expect it to be getting brighter instead of dimmer.

  • But there is something that my team and I noticed during our research that totally caught us off guard:

  • Betelguese is rotating REALLY fast.

  • Like, 150 times faster than we'd expect for a star of its size!

  • So, what gives?

  • Well, to explain it's observed rotational velocity, we think it may have actually gobbled up another star.

  • The idea is that when Betelguese ballooned to a red supergiant, it took a nearby star with it,

  • absorbing that star's rotational velocity angular momentum and started spinning faster as a result.

  • While we continue to monitor Betelgeuse's behavior and watch for any indication of what its future holds,

  • we can be certain that its striking presence in the night sky will continue to hold our interest.

  • For the time being, anyway.

  • And whenever Betelguese does explode as a supernova, we can look forward to an amazing light show.

  • It'll shine as bright as the moon for weeks on end; so bright that it will be visible during the day!

  • I'm Sarafina Nance and this is Seeker Constellations.

  • Thanks so much for watching this season of Constellations, I had such a blast!

  • If there's another astronomy topic that you'd like to see us cover, let us know in the comments.

  • Thanks for watching!

Betelguese is truly a star.

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Betelgeuse Is Destined to Explode as a Supernova…But When?

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    Summer posted on 2021/04/09
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