Betelgeuse! Betelgeuse! BETELGEUSE!

[Spookie Monster]

You know Betelgeuse: It's a star, a red supergiant, in the constellation Orion (specifically, it's Orion's left shoulder).  Well...

Popular Giant Star Shrinks Mysteriously

A massive red star in the constellation Orion has shrunk in the past 15 years and astronomers don't know why.

Read more here and here.

I find this extremely interesting.  If the measurements are accurate, then I want to know what's going on.  If the measurements are inaccurate, then I want to know what's going on.

Enjoy!

Spel

How you moved is all it takes...

[Indigo]

Ah...that's a significant thing....basically, it's reducing in size by roughly 1% per year since '93....without losing it's brilliance.  The forces must be incredible!

The first documented case maybe, of a red giants death, into nova or massive collapse? Very interesting, quite right.

[Oniya]

Of course, it doesn't say whether the shrinkage has been linear or geometric.  It would be interesting to see if the rate of change is increasing, decreasing or constant.

[Vekseid]

There's a lot of speculation about the exact life cycle of large stars. Red dwarfs are pretty simple in terms of mechanics, as are smaller stars like our own. Stars destined for supernova - more than about eight solar masses - are rather more mysterious.

One suggestion is that red supergiants like Betelgeuse eventually throw off their red outer envelope, which is really less star and more ionized hydrogen gas cloud. Think about it, the density of the top of our Sun's photosphere is about 1.3x10^17 particles per cubic centimeter - compare to ~6.022*10^20 for Earth's atmosphere. Now you pack twenty times the Sun's mass in a billion times the volume. ~3x10^9 particles per cc is only a few orders of magnitude away from dense molecular clouds.

Obviously, Betelgeuse's core is far, far denser, it's just important to remember that while the part we see is obviously the most conspicuous, it really doesn't make up much, mass wise.

[The Overlord]

Though the red supergiant stage is the beginning of the end of a main-sequence star like our sun, and only after the better part of ten billion years have elapsed, the burns stage as a giant is still an awesomely long span of time from a human perspective.

But a 15% diameter change in less than two decades...that's quick as hell even for a massive star. By at least one estimate, Betelgeuse could go supernova at any point between tonight and ten million years from now.

Then again, quoting the sources cited on Wiki-

It is possible that Betelgeuse will become a supernova, which will be the brightest ever recorded, outshining the Moon in the night sky. Considering its size and age of 8.5 million years, old for its size class, it may explode within the next thousand years. Since its rotational axis is not toward the Earth, Betelgeuse's supernova would not cause a gamma ray burst in the direction of Earth large enough to damage its ecosystem, and also because of its 640 light year distance.


As has been often repeated, no supernova have gone off relatively close to us since the invention of the telescope, but obviously those numbers are going to catch up with us sooner or later. If Betelgeuse goes up, it's going to be a sight for the ages, in both the night and daytime sky.

[Spookie Monster]

You know Betelgeuse: It's a star, a red supergiant, in the constellation Orion (specifically, it's Orion's left shoulder).

BLEH!  Betelgeuse is NOT Orion's left shoulder.  TO REPEAT: Betelgeuse is NOT Orion's left shoulder.  Bellatrix is Orion's left shoulder.  Betelgeuse is Orion's right shoulder; it's only on the left as we view it.  Please believe me: I can speak the English, I'm familiar with astromony, and I know my right hand from my right hand!  Many apologies if my foolish error caused you to answer the $64000 question incorrectly.

For further clarity, here's a picture of Orion with a cow in place of Betelgeuse:



This picture should answer several questions, such as Where exactly is Betelgeuse? and Is Spel just odd or is he in fact certifiably insane?.

With regard to the "shrinkage" itself... who can say?  Hopefully, if we keep watching, we can figure it out.  Maybe it just took a dip in a cold pool?

Spel

Did the world just explode?

[The Overlord]

For further clarity, here's a picture of Orion with a cow in place of Betelgeuse:



This picture should answer several questions, such as Where exactly is Betelgeuse? and Is Spel just odd or is he in fact certifiably insane?.



Spel

Did the world just explode?

Spel, representatives from Chick-fil-A will be contacting you soon. I think you've just given them another good one to fuel their advertising campaign.



Cosmic Cow tells mortals to...EAT MOR CHIKIN!!

[Spookie Monster]

Spel

She soars into town just like a sacred cow...

[Mnemaxa]

I find it somewhat amusing that this is being spoken of in the present tense in a lot of cases.  Whatever is 'going on' with Betelgeuse has already happened several generations ago - we're just now able to obverse it.  Light has a speed limit....

It's no less interesting, for all that, mind you, but it is an interesting point to note that this outcome is predestined in the most absolute way possible....

[Sho]

I also find it somewhat amusing that every time I see this topic, I read it as "Beetlejuice" instead of "Betelgeuse".

[The Overlord]

I find it somewhat amusing that this is being spoken of in the present tense in a lot of cases.  Whatever is 'going on' with Betelgeuse has already happened several generations ago - we're just now able to obverse it.  Light has a speed limit....

It's no less interesting, for all that, mind you, but it is an interesting point to note that this outcome is predestined in the most absolute way possible....

It’s likely to be the most comfortable way to speak on astronomical topic. Everyone learned on the topic knows what we’re seeing is in the past, and can be measured in light years, but when a star goes supernova, etc. the event occurs for us ‘now’.

Observers on a planet many light years from Earth will see the star explode at a different time than we; it’s about establishing a reference point for us, and it’s not very useful to use a distantly past or future point for that purpose.


Also, pre-destiny has nothing to do it. The event has already happened, and without any manner or fate or prophecy…we’re just getting the news late. No more, no less.

[Will]

It’s likely to be the most comfortable way to speak on astronomical topic. Everyone learned on the topic knows what we’re seeing is in the past, and can be measured in light years, but when a star goes supernova, etc. the event occurs for us ‘now’.

Observers on a planet many light years from Earth will see the star explode at a different time than we; it’s about establishing a reference point for us, and it’s not very useful to use a distantly past or future point for that purpose.


Also, pre-destiny has nothing to do it. The event has already happened, and without any manner or fate or prophecy…we’re just getting the news late. No more, no less.

It's just an interesting way of looking at it.

[Arazel Eternal]

Whats even more intresting is the fact that the star may not even exist anymore and we are still seeing its light.  If the star is, lets say, 250 light years away from us, it is taking the light from that star 250 years to get to us.  So, for all we know, that star may not exist anymore but we are still seeing its light because it has taken so long for it to get to us, and the end of it just hasnt arrived yet. 

As Betelgeuse is 570 light years away from us, and we can never accurately know how old it is, it may have already died and we are just seeing what is now getting to us.  Those are my thoughts anyway, I could be full of it.  Have been before.   ;)

[Will]

Well, a star isn't going to vanish completely, even over billions of years.  It will leave a white dwarf, neutron star, or a black hole, depending on the case.  I'm not actually sure what Betelgeuse will end up as, but the article seemed to imply it was massive enough to form a black hole upon its collapse.  Of course, that also depends on whether it's losing mass as it shrinks, or just volume.

[Vekseid]

Betelguese has 20 solar masses, so it would form a high-mass neutron star.

It is possible for a supernova to undergo complete disintegration, however - pair instability supernovas do not leave a black hole, for example, and Type Ia supernovas are also complete disintegration events.

[The Overlord]

Whats even more intresting is the fact that the star may not even exist anymore and we are still seeing its light.  If the star is, lets say, 250 light years away from us, it is taking the light from that star 250 years to get to us.  So, for all we know, that star may not exist anymore but we are still seeing its light because it has taken so long for it to get to us, and the end of it just hasnt arrived yet. 

As Betelgeuse is 570 light years away from us, and we can never accurately know how old it is, it may have already died and we are just seeing what is now getting to us.  Those are my thoughts anyway, I could be full of it.  Have been before.   ;)

Based on the current knowledge of Betelgeuse, it could blow in a thousand years and it might blow next week. And yeah, that’s the really funny part about relativity and the vastness of space; if it goes up next Sunday that means while it existed for the ancients in their time, it’s technically been gone since about the time of Columbus.

Weird, even if we understand why.

[Will]

Betelguese has 20 solar masses, so it would form a high-mass neutron star.

It is possible for a supernova to undergo complete disintegration, however - pair instability supernovas do not leave a black hole, for example, and Type Ia supernovas are also complete disintegration events.

I stand corrected!  >.<

[Spookie Monster]

As Betelgeuse is 570 light years away from us...

Out of curiosity, do we actually know how far away Betelgeuse is?  I was under the impression that we didn't; indeed, this page, which Wikipedia itself relies upon for the facts regarding Betelgeuse's distance, states:

The star's distance is a problem and a puzzle (true for all the other parameters as well).  Direct parallax measures from space, using the most modern results, give 495 light years, whereas the parallax using the star's natural radio emission gives 640 light years.

I find it fascinating that astronomers and astrophysicists are coming up with all of these measurements, all of these theories, all of these predictions about Betelgeuse's changes... and yet can't tell us how far away the darn star is in the first place.

Spel

Take your time...

[The Overlord]

Yet the stat distance on the original Wiki page is sitting at 430ly I guess they had to put something. Look at one of the cited sources (#4).

However, the star is surrounded by a huge complex pattern of nested dust and gas shells, the result of aeons of mass loss, that extends nearly 20,000 AU away (Betelgeuse so far having lost over a solar mass). That, an extended atmosphere, and the pulsations make it difficult to locate an actual "surface" to tell just how large the star actually is. Moreover, because of changes in gaseous transparency, the "size" of the star depends on the color of observation. Long-wave infrared measures give a vastly larger radius of up to 5 AU and greater, as big as the orbit of Jupiter, while shorter-wave infrared light gives as small as 3 AU. Moreover still, infrared measures reveal Betelgeuse to be shrinking (by some 15 percent over about 20 years), and other measures show that the star is not even round, but somewhat oval. Hubble observation also shows hot spots. It's no wonder that we find the various disagreements. It's more surprising that all agree as well as they DO. Whatever the actual numbers, Betelgeuse is clearly a highly evolved star, one whose central hydrogen fuel supply has run out. As a result, the core has contracted into a hot dense state, and the outer portions swelled outward. We do not really know the star's condition at the moment, but the odds are that it is now in the process of fusing helium into carbon and oxygen in its core. From theory, its initial mass should have fallen somewhere around 18 or 19 times that of the Sun. Starting life as hot, blue, class O star only around 10 million years ago, Betelgeuse will fuse elements through neon, magnesium, sodium, and silicon all the way to iron. The core will then collapse, causing the star to blow up as a supernova, most likely leaving a compact neutron star about the size of a small town behind. If it were to explode today, it would become as bright as a gibbous Moon, would cast strong shadows on the ground, and would be seen easily in full daylight.

It seems a fair amount of it is based on theory still. If they’re not positive on even the mass or shape and size of the star, luminosity might be throwing the entire thing off. Now the page says measurements are based on a parallax but there's a practical distance limit using that, and I'm wondering if distance and other factors are skewing the results.