Citizen Science for Epsilon Aurigae

January 8, 2009 10:49 PM

Once every 27 years or so, the mysterious binary star system of Epsilon Aurigae undergoes an eclipse, lasting nearly two years. This gives this system the distinction of having both the longest eclipse and the longest period of any known binary system. However, it is not clear why the eclipses last so long, or even what the structure of the system actually looks like--the main star is a supergiant, with a radius as big as the distance from the earth to the sun, and yet its light is dimmed for two years by something yet bigger. The next eclipse is due to begin in August of 2009, and as part of the International Year of Astronomy in 2009, amateur astronomers are being called on to make their own observations of the changing brightness of Epsilon Aurigae. If you want to try it yourself, you can read the training guide to find out how to do your own observations and report them. In addition, the two scientists who organized observations of the previous eclipse both have webpages [1, 2] which are coordinating the organization for the upcoming observation. If you want to learn more about the science behind ε Aurigae, a good rundown with links to papers is available here.
posted by Upton O'Good (32 comments total)

Odder yet, it is the big class F supergiant that gets eclipsed, by something that is vastly larger than it! And no one knows quite what. The prevailing model is that Almaaz is in mutual orbit with a star that is surrounded by a thick ring of obscuring dust set nearly edge on. Almaaz proper (the supergiant we see) and the mystery star are perhaps 30 Astronomical Units apart, the dust ring about the secondary star some 20 AU in diameter. The ring has some sort of doughnut hole in the middle, as Almaaz brightens a bit at mid-eclipse. We have little idea what lies in the dusty ring. One theoretical model says something of 4 solar masses, another of 15. It could be one star that has generated a disk through a fierce outflowing wind or (as more commonly believed) a pair of class B stars that are themselves in tight orbit.

This is some fucking cool shit.
posted by Artw at 10:59 PM on January 8, 2009 [2 favorites]

It's either a precessing ringworld, or a partially-finished Dyson sphere.
posted by nicwolff at 12:01 AM on January 9, 2009 [1 favorite]

Yeah, I vote for half-finished Dyson sphere. I think it's in the wrong direction to be OnOff.
posted by hattifattener at 12:09 AM on January 9, 2009

Could this be a sign the universe doesn't revolve around me?

Naahhh.
posted by notreally at 3:16 AM on January 9, 2009

That's no moon!
posted by Faint of Butt at 3:32 AM on January 9, 2009 [2 favorites]

OMFGSPACEDONUT!
posted by Jofus at 3:41 AM on January 9, 2009

the main star is a supergiant, with a radius as big as the distance from the earth to the sun, and yet its light is dimmed for two years by something yet bigger.

Guess: a weapon of unimaginable destructive power

Actually, for me the cool part of this story isn't the space donut. Well, that's one of the cool things. The coolest thing is the citizen science part. There's a lot of brains and eyes out there, people. Let's use them.
posted by DU at 4:59 AM on January 9, 2009

And then the flying raptors shoot out of their underground dens, hooting, with forks and knives and napkins tucked into their collars, and eat us all in the pitch dark.
posted by steef at 5:17 AM on January 9, 2009

Damn. I thought a Dyson Sphere was the vacuum cleaner of choice for the style conscious.
posted by rhymer at 5:36 AM on January 9, 2009

This is pretty interesting too.
posted by popcassady at 5:51 AM on January 9, 2009

This is pretty interesting too.
posted by popcassady at 5:51 AM on January 9

What, this?

"I remember reading a reference to a report to the effect that it might be possible that a high mass specific yield themonuclear device detonated deep under the Earth’s ocean might have a chance at starting a propagating fusion chain reaction within the Earth’s oceans that would race around the globe on the order of one second thus effectively turning the Earth’s oceans into a thermonuclear device with a mass of about 10 EXP 18 tons and a yield of about 10 EXP 26 tons of TNT or the equivalent mass in TNT of a M class star."

I'm no astrophysicist, but I believe the proper response to this is: "That’s not right. It’s not even wrong."
posted by Optimus Chyme at 7:16 AM on January 9, 2009 [2 favorites]

Optimus: The concept sounds downright wacky, but natural processes of pressure and bizarre circumstances leading to natural-born nuclear reactions are not unheard of. Whether or not deep sea conditions would be similarly feasible to recreate the scenario is a bit hazier... heh. All I know is that they better not wreck my house trying it out.
posted by FatherDagon at 7:37 AM on January 9, 2009

Fascinating. Thanks.
posted by Durn Bronzefist at 7:48 AM on January 9, 2009

Here is a nice article on searching for evidence of alien astroengineering.
posted by euphorb at 7:56 AM on January 9, 2009

One of the predominant nuclear physicists who worked on the development of the Hydrogen bomb has reportedly once calculated that a 100 kilometer or so wide thermonuclear device made with utmost precision, a sort of homogenous thermonuclear crystal, if detonated in an appropriately spherically symmetric and judicious radial pattern, could actually produce tiny but macroscopic massed blackholes near or at the center of the exploding device.

Cite please!
posted by Artw at 9:02 AM on January 9, 2009 [1 favorite]

Awesome post. Since Dyson Spheres have been mentioned here, I'd like to share this BBC article about space elevators.
posted by Curry at 9:09 AM on January 9, 2009

I will freely admit that I don't know shit from shineola, but I think a good part of astronomy is pure BS. To me it appears to be a castle built on a foundation of a chain of assumptions. But what do I know? Ninety per cent of my smarts is dark intelligence not visible to the naked eye.
posted by digsrus at 9:30 AM on January 9, 2009

Yeah, it’s like they’re just trying to build some kind of model of what the universe is like through observations and then disprove it with more observations, and then the model they come up with to deal with that is really weird and has lots of grey areas that may be updated at a later date!
posted by Artw at 10:03 AM on January 9, 2009 [5 favorites]

To me it appears to be a castle built on a foundation of a chain of assumptions.

Yes, that's why the error bars are so big.
posted by pointless_incessant_barking at 10:26 AM on January 9, 2009

Mystery radio signal could be from universe's first stars
posted by Artw at 10:37 AM on January 9, 2009

euphorb, Artw

Oops. No, I meant to link to the main article not the comment.
posted by popcassady at 10:58 AM on January 9, 2009

Space elevators, meh; space fountains!
posted by nicwolff at 12:38 PM on January 9, 2009

Can someone explain why the other object has to be bigger, and not just closer?
posted by swift at 1:45 PM on January 9, 2009

I think the object in nicwolffs link is all about being bigger.
posted by Artw at 1:59 PM on January 9, 2009

swift: Because it occludes the visible star every 27-odd years, it's pretty likely that it's actually orbiting that star. It could be something closer to us, but then you'd have to figure out why it's remained so precisely lined up between us and Aurigae.
posted by hattifattener at 2:04 PM on January 9, 2009

So that's where the Lord Tedesco parked the Golden Ship.

/obscure enough to cause said eclipse all by myself
posted by Iosephus at 4:15 PM on January 9, 2009 [2 favorites]

Dude, you;ve clearly never scoped out how fast the obscure Sci-Fi questions get answered in AskMe if you think you can throw us with a Cordwainer Smith reference.
posted by Artw at 4:22 PM on January 9, 2009 [3 favorites]

Can someone explain why the other object has to be bigger, and not just closer?
If its orbiting, and the same size, it would eclipse for a short time, not two years.
posted by uni verse at 5:43 PM on January 9, 2009

Why couldn't it be a very massive black hole that εA is orbiting? If εA has an orbital period of, say, 29 years, it seems reasonable that for two of those years its light is completely occluded by the gravity well of the black hole.
posted by sonic meat machine at 8:57 PM on January 9, 2009

Because black holes aren't large, and they generate a huge amount of radiation when they're orbiting a star.
posted by empath at 9:15 PM on January 9, 2009

Oh hey! Cordwainer Smith reference!

HI FIVE!

Mental note to self: Read more Cordwainer Smith this year
posted by Kattullus at 9:32 PM on January 9, 2009

empath, black holes only generate large amounts of visible radiation when they have an accretion disk. A star orbiting a black hole at a great enough distance might not be losing material into it - per Kepler's 3rd law (which holds for an outside observer) the longest radius of a 27-year orbit would be 9 AUs if you can disregard the mass of the orbiter, I guess it would be longer in a two-body system? Hello, physicists?

And the star's light would be eclipsed to an observer on Earth not only while it transited behind the black hole but for the whole time that the black hole was warping its light, which I guess could be 2/27 of its orbit.
posted by nicwolff at 3:21 PM on January 10, 2009