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betelgeuse is down 100 kelvin since september

Hagbard Celine

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Hagbard Celine

Hagbard Celine 10849

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it may mean fuckall.  the halflife on expiration is 1 million years.  it's had several magnitude darkenings since astronomy.

but if you have been looking at it every winter night for 40 years, you can see the change.

 

it's not red anymore.

and it no longer rivals sirius.

 

go outside right now.   it could be the last time you ever seen Orion as we've always known it.

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Hagbard Celine

Hagbard Celine 10849

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During the 25-years of V-band / Wing Near-IR photometry, Betelgeuse is currently the coolest and least luminous yet observed. Since September 2019, the star's temperature has decreased by ~100 K while its luminosity (inferred from the C-band/m-bol observations) has diminished by nearly 25%. At face value using R'/R = [(T'/T)^4 / L'/L]^0.5 (where R', T' and L' are the current values of stellar Radius, Temperature & Luminosity), this implies an increase of the star's radius of ~9%. However, as pointed out by others, the current fainting episode could also arise from expelled, cooling gas/dust partially obscuring the star. The recent changes defined by our V-band/Wing photometry seem best explained from changes in the envelop-outer convection atmosphere of this pulsating, unstable supergiant. If these recent light changes are due to an extra-large amplitude light pulse on the ~420-day period, then the next mid-light minimum is expected during late January/early February, 2020. If Betelgeuse continues to dim after that time then other possibilities will have to be considered. The unusual behavior of Betelgeuse should be closely watched.

http://www.astronomerstelegram.org/?read=13410

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Hagbard Celine

Hagbard Celine 10849

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Betelgeuse is Continuing to Dim! It’s Down to 1.506 Magnitude

Betelgeuse keeps getting dimmer and everyone is wondering what exactly that means. The star will go supernova at the end of its life, but that’s not projected to happen for tens of thousands of years or so. So what’s causing the dimming?

Villanova University astronomers Edward Guinan and Richard Wasatonic were the first to report Betelgeuse’s recent dimming. In a new post on The Astronomer’s Telegram, the pair of astronomers report a further dimming of Betelgeuse. They also point out that although the star is still dimming, its rate of dimming is slowing.

Betelgeuse is a red supergiant star in the constellation Orion. It left the main sequence about one million years ago and has been a red supergiant for about 40,000 years. It’s a core-collapse SN II progenitor, which means that eventually, Betelgeuse will burn enough of its hydrogen that its core will collapse, and it will explode as a supernova.

It’s known as a semi-regular variable star, which means its brightness is variable. One of its cycles is about 420 days long, and another is about five or six years. A third cycle is shorter; about 100 to 180 days. Though most of its fluctuations are predictable and follow these cycles, some of them are not, like the current dimming.

Astronomers have been monitoring Betelgeuse for a long time. Visual estimates of the star go back about 180 years, and since the 1920s, the American Association of Variable Star Observers (AAVSO) have taken more systematic measurements. About 40 years ago astronomers at Villanova University began taking systematic photometric measurements of Betelgeuse’s brightness. The photometry data from the last 25 years is the most thorough, and according to that data the star is as dim as it’s ever been.

According to Guinan and Wasatonic’s post on Astronomer’s Telegram, Betelgeuse’s temperature has dropped by 100 Kelvin since September 2019, and its luminosity has dropped by nearly 25% in the same time frame. According to all of those measurements, the star’s radius has grown by about 9%. This swelling is expected as Betelgeuse ages.

In a way, we’re lucky to have Betelgeuse so close by, in astronomical terms at least. It’s only about 650 light years away, and that makes it a great teacher. It’s the only star other than our Sun on which we can see surface details. That helps astrophysicists understand what’s happening there, and on other similar stars.

Like all stars, Betelgeuse generates heat in its core through fusion. The heat is transferred to its surface via convection. The currents that carry the heat are called convection cells, which can be seen on the surface as dark patches. As the star rotates, these cells rotate in and out of view, which contributes to Betelgeuse’s observed variability. Convection cells can be massive, even more so on the surface of a huge star like Betelgeuse. In 2013 scientists reported evidence of convection cells on the Sun that lasted for months. It wasn’t conclusive, but could something like that be happening on Betelgeuse, contributing to the dimming?

This dimming episode may not be the star itself, but rather a cloud of gas and dust obscuring the light. As time goes on, and Betelgeuse burns more of its fuel, it loses mass. As it loses mass, its gravitational hold on its outer edges is weakened, and clouds of gas escape the star into the surrounding regions. This could cause the current dimming episode.

Or could it be something else? We know a lot about stars, but we don’t know everything. We’ve also never been able to observe any other red super-giants the way we can with Betelgeuse.

Astronomers Know What’ll Happen, They Just Don’t Know When.

Whatever the cause, we know what the eventual end for Betelgeuse looks like: a supernova explosion. Whether this dimming is directly related to the approaching cataclysmic death of this unstable star is unknown at this point. As Guinan and Wasatonic say on Astronomer’s Telegram, “The unusual behavior of Betelgeuse should be closely watched.”

When Betelgeuse does eventually go supernova, it will be the most fascinating act of nature witnessed by any human ever. Other supernovae like SN 185 and SN 1604 were much further away than Betelgeuse. When Betelgeuse goes supernova, it will the third brightest object in the sky, after the Sun and the full Moon. But some estimates say it’ll be even brighter than the Moon.

That brightness will last months, and it’ll cast shadows on Earth even at night. Then in about three years or so, it will dim down to its current brightness.

Betelgeuse will light up the sky like no other supernovae, and will last for months, visible in daytime, and casting shadows at night. Then in about three years, it will fade to its current brightness. Then in about six years after it goes supernova, Betelgeuse won’t even be visible in the night sky. Orion the Hunter will be no more.

When exactly all this will happen, nobody knows. And though this recent dimming likely isn’t directly connected to Betelgeuse’s eventual supernova explosion, astronomers don’t know that for sure either.

 

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Hagbard Celine

Hagbard Celine 10849

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Is Betelgeuse going to blow? Scientists reveal the truth about a "dying" star.

Over the past few weeks, one star in our cosmic neighborhood has enjoyed unparalleled celebrity. That's because Betelgeuse, a star in the constellation Orion, may soon die and explode in a supernova. Despite the hype, scientists don't yet know for sure if, or when, it will. To get to the bottom of this stellar saga, Inverse went to the experts, and the news is good:

We will have answers — and soon.

The news of Betelgeuse's possible death broke earlier this month — and the world collectively lost its sh*t, scientists included. Edward Guinan, an astrophysics professor at Villanova University, was watching the news on CNN when the anchor announced that a burst of gravitational waves had been detected from around the constellation Orion on January 14, 2020.

“I immediately jumped out of bed,” Guinan tells Inverse.

Guinan is all too aware of the star's meteoric rise in the public consciousness — after all, it was his initial observations that sparked the hype around the star's seemingly impending demise.

For new Betelgeuse-watchers out there, Guinan has an important update to the saga: Within the next couple of weeks, he will be able to predict whether or not the star will actually explode, he tells Inverse.

“It’s like a lottery ticket, very low probability but life changing.”

Guinan began observing Betelgeuse in 1981 — long before it was cool. It was a practical decision, he says: It is a bright, nearby star in the prominent constellation of Orion. But despite his long admiration of the star, Guinan admits that he had been getting ready to give up on Betelgeuse.

“It’s been 25 years, we were getting tired of it,” Guinan says. “Let’s give it one more year before we stop observing it.”

As if on cue, things started to get interesting. In November 2019, the star began to dim. At first, Guinan didn’t think it was unusual — the star often varies in brightness. But this time, it was different — rather than continue varying in luminosity, the star's brightness kept decreasing.

“It didn’t stop, it just kept going,” Guinan says. “Whenever we thought it’s near the end, it can’t go anymore, it would go more.”

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Guinan and his colleagues reported the dip in Betelgeuse’s brightness on The Astronomer’s Telegram on December 8, 2019 — to find out what was going on, they also put out a call for other astronomers to start observing the star as well.

Astronomers worldwide answered, and so began the growing consensus that Betelgeuse wasn't just acting strange — it was on the verge of exploding.

Front row seats to a supernova...

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As a star nears the end of its life, it runs out of fuel and essentially collapses under its own gravity. The death of a giant star results in a massive explosion witnessed across galaxies, a supernova.

Astronomers have only been able to observe supernovae faint stars in distant galaxies. Because of the distance, these supernovae are only detected long after the star has exploded. But Betelgeuse is right here in our neck of cosmic woods — being this close to the star means that scientists could observe the entire process from start to finish in unprecedented detail.

“We’ll have a front-row seat observation to what happens when a star becomes a supernova,” Guinan says.

The problem is knowing when that might happen. Astronomers aren’t exactly sure what happens before a star goes supernova, so it’s hard to predict whether Betelgeuse will explode tomorrow -- or 100,000 years from now. When Betelgeuse explodes remain a cosmic mystery.

“No one has ever really seen a star before it became supernova, or measured it for weeks or months before it happened,” Guinan says. “There’s no precedence, there are no clues.”

Right now, the star is 20 percent dimmer than usual, but scientists still aren't sure whether this is part of the star’s irregular behavior or if Betelgeuse is about to give us the show of a lifetime.

"It’s not something you get to see very often, seeing a prominent star change its brightness."

“There’s a very, very, very low chance that it would blow up, but if it does -- then it would completely change my life,” Andy Howell, staff scientist at Las Cumbres Observatory Global Telescope Network, tells Inverse. “It’s like a lottery ticket ... very low probability but life-changing.”

If Betelgeuse were to explode, it should brighten again. The exploding star would reach peak brightness after a week or so, becoming as bright as the full Moon in the night sky and casting a shadow on Earth. The detonation would also be visible during the daytime, similar to how Venus looks in twilight. Its light would last for a few months, before it plateauing and eventually completely fading from our vision over the course of a year or two.

Aside from the awe-inspiring sight of a star visible during the day, it would be an incredible learning opportunity for scientists around the world. An astronomical event of this size would make everyone hyper-aware of astronomy and the intricate science behind our stars, Howell says.

Observing a supernova in real time would also provide insight into some of the still-unexplored physics behind the stellar explosions, he says.

“People have been trying to simulate supernova for decades,” Howell says. “But in the simulators, they haven’t been blowing up.”

Because our knowledge of these events is incomplete, astronomers think they are likely still missing a piece of the puzzle behind what causes a star to explode.

What's the back-story on Betelgeuse?

Betelgeuse was already pretty popular even before all this talk of its imminent death. A quick look at its vital statistics demonstrates why.

Betelgeuse, pronounced "beetle-juice," is a red supergiant star located around 640 lightyears away in the constellation Orion. It is a variant star, meaning that it varies in brightness in a range between +0.0 and +1.3, but it is consistently one of the brightest stars in our sky.

Due to its brightness, Betelgeuse can be observed using small telescopes and is a favorite among amateur astronomers.

Betelgeuse is so big that if it were in our Solar System, it would engulf Mercury, Venus, Earth, Mars, and Jupiter.

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Irene Pease, president of the Amateur Astronomers Association of New York, has been observing Betelgeuse for over a decade. She was able to notice the star dimming by just looking up at it at night.

“Just looking up in the sky, I can tell,” Pease tells Inverse. “It definitely looks different.”

When news of the star’s dimming broke out, celebrity astrophysicist Neil deGrasse Tyson called on amateur astronomers everywhere to keep their telescopes on Betelgeuse and monitor its brightness, the New York Times reported.

Since there are more amateur astronomers than professionals in the world, there’s a better chance that they would see it first, Pease says. Even if the star doesn’t go supernova, Pease still encourages people to go out and observe it for themselves.

“It’s definitely a novelty because we don’t really know what’s gonna happen so it’s kind of exciting,” Pease says. “It’s not something you get to see very often, seeing a prominent star change its brightness.”

The conversation around Betelgeuse going supernova has made astronomy accessible to more people, experts say. The star even has its own fake Twitter account, which tweets out updates such as, “I install one dimmer switch in my dining room and the entire galaxy loses its shit.”

“You call it hype, but it’s my life,” Howell says. “I think about Betelgeuse all the time.”

He is not alone — Guinan, so close to giving up on Betelgeuse, has renewed passion for the star. “It’s a star I’ve grown quite fond of,” Guinan says. “I’ve been observing it for close to 30 years and I always know what it’s gonna do, until now.”

Guinan has started drafting a paper on the dimming of Betelgeuse. But he’s still not quite sure what the conclusion of the paper will be.

He should know that within the next three to four weeks, he says. If the star starts regaining its brightness, then the dimming was part of its variant nature. “This is a small sample of its life, it may have done this in the past and no one noticed it,” he says.

But should it continue to decrease in brightness, then it may be a sign that it really is getting ready to go supernova. And if it does, both amateur stargazers and astronomers will be thrilled.

“When you look up at the sky, you always take a couple of seconds to wish upon a star,” Howell says. “I’m always wishing for Betelgeuse to blow up.”

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Braff Zacklin

Braff Zacklin 13552

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Night sky watchers who lived around the turn of the 11th century had it good.

Not only were they witness to SN 1006, which astronomers estimate to be the brighest stellar event in recorded history, they also observed SN 1054, which led to the formation of the Crab Nebula, if they lived long enough.

Both were reportedly bright enough to be seen during the day.

Betelgeuse probably won't go anytime soon (or form a black hole), but the imagery would be dazzling given today's optics.

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Hagbard Celine

Hagbard Celine 10849

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from a week ago yesterday on the 1st.....

astromath geeks click here: http://www.astronomerstelegram.org/?read=13439

tl/dr:

But as a caveat, this estimate is bolometric-based and assumes the changes originate from a spherically symmetric star. The light changes also could arise from changes in circumstellar dust and/or variations in localized bright or dark regions on the star. Adopting a more refined determination of the dominant (probable pulsation) period of P = 430 days, the minimum brightness is expected on 21 (+/-7d) February, 2020. The most recent photometric observations indicate that Betelgeuse is currently the least luminous and coolest yet measured from our 25-years of photometry. Observations made over the last few weeks indicate that current dimming could be slowing. Observations (of all kinds) over the next few months will be important. We are preparing a paper on these results for publication.

+++

So the new date for "new news" is the end of the month.  Dimming could be slowing.

The new paradigm is this: we may have lived in the era of solar system discovery, and witnessed the red giant shoulder of Orion dim, which is the biggest change in the visible sky since 1054.

And this may be all we get.

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Hagbard Celine

Hagbard Celine 10849

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dimming has stopped.  could brighten again back to 'normal', or this could be the 'new normal'....

+++

http://www.astronomerstelegram.org/?read=13512

Based on these and additional observations, Betelgeuse has definitely stopped dimming and has started to slowly brighten. Thus this "fainting" episode is over but additional photometry is needed to define the brightening phase. An ESO VLT/SPHERE IR image of Betelgeuse was secured during late 2019 December by M. Montarges et al. (2020: paper in preparation). The stunning VLT/SPHERE image shows that most of lower half of star has significantly dimmed, thus providing a spatially resolved image of the star informing about the observed dimming. (https://www.eso.org/public/news/eso2003/). At the time of the VLT/SPHERE observations, Betelgeuse's brightness was V ~ +1.3 mag. As mentioned above, the star subsequently dimmed to ~1.6 mag during mid-February 2020. Observations of all kinds continue to be needed to understand the nature of this unprecedented dimming episode and what this surprising star will do next.

https://www.eso.org/public/news/eso2003/

eso2003c.jpg

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