Category Archives: circumstellar disks

Alien Merry-Go-Round Discovered?

Nope. But, there IS a Star with Something REALLY Cool!

An artist's concept of a Ring World around a star, a concept written about by SF writer Larry Niven. Image Courtesy Hill, CC By-SA 3.0.
An artist’s concept of a Ring World around a star, a concept written about by SF writer Larry Niven. Image Courtesy Hill, CC By-SA 3.0.

Alien hunters in the mainstream media were delighted to hear that the Kepler mission to search out distant exoplanets found what they thought was unmistakeable evidence of life elsewhere in the universe — preferably little green beings with medical instruments and the keys to one spaceship for everybody on the planet.

As the old Etta James song goes, “At last….”

Time to break out the 72-point Chiller typeface and pictures of alien greys with giant eyes, right?

Not so fast, kids. The evidence for the breathless hype about aliens this week comes from an actual science result that got misinterpreted. There’s a paper published by a group of explanet researchers, coupled with observers involved in a planet-search strategy called  the Planet Hunters Project (a citizen science project through Zooniverse). It talks about the variability of light coming from a star and gives some ideas about what’s causing it. Their combined work actually points to something far more fascinating and much more likely than aliens: the break-up of comets that are orbiting around the distant star called KIC 8462852. It’s an interesting story with some really cool twists. But, the paper doesn’t mention aliens.  At all.

Of course, that fact hasn’t been enough to stop an amazing roar of speculation by the usual gang of suspects in the pulp press online and in meatspace, who have already jumped on the ALIENS!!!!! OHMYGAWD!!!! bandwagon and declared in breathless headlines that astronomers have ACTUALLY found little green men, Dyson spheres, alien solar panels, and supermegagigastructures made of gold-pressed latinum surrounding the star, or whatever else gets dreamed up in the moist, sweaty fever swamps inhabited by alien discovery fans.

Just the Facts, Ma’am

Let’s science the you-know-what out of this story, shall we? The paper based on the actual science is online at ArXIV, an online publication service for astronomers. If you’re interested in the science story behind the online fever dreams, take a few moments to read the paper (the abstract and conclusions should give you the executive summary). You’ll find out that the observation team spent several years counting “dips” in the brightness of the starlight coming from this star. Those dips indicate something is blocking the light, creating not-so-periodic “dips” that occur from anywhere to 5 to 80 days apart. What could the “something” be?

An artist's conception of a circumstellar disk around a star, complete with colliding objects that might explain dips in a star's brightness as the fragments orbit the star. Scientists do not think there is a planet around the target star in this story, however. Image courtesy JAXA.
An artist’s conception of a circumstellar disk around a star, complete with colliding objects that might explain dips in a star’s brightness as the fragments orbit the star. Scientists do not think there is a planet around the target star in this story, however. Image courtesy JAXA.

Differential Diagnosis: Speculation vs. Observational Data

According to the mainstream media research team, joined by their colleagues in the tin-foil media, the only plausible explanation for the dips are due to strange alien constructs surrounding the star. This is apparently the only solution they could come up with on the spur of the moment.

Contrast that with the research team and the Planet Hunter team, which — with four years of observational data — looked into several naturally occurring possibilities among the processes that are actually work around the star. They include searching for evidence of the kinds of things that would logically be expected: possible variability in the brightness of the star itself,  some kind of variability caused by a nearby dwarf star, light-blocking by orbiting dust clumps near the star, and instrument error.

The scientists ruled out these possibilities before settling on a fairly intriguing but quite plausible idea: the passage of a family of exocomet fragments as they orbit the star. Collision debris orbiting the star could explain the four years of observational evidence, although more observations will help them determine if it’s the right explanation. Among other things, astronomers would expect a large amount of dust to be orbiting the star, too, distributed as a result of the collisions. However, there should also be some kind of evidence when they look at it in infrared light, since dust has a very distinctive “fingerprint” in infrared. However, that hasn’t been detected, so there’s still some work to be done to figure out what is going on around the star.

Where DID the Aliens Come From in this Discussion?

So, you might be wondering how a simple story about dips in stellar brightness came to be festooned with alien implications. It turns out, the team did talk to astronomer Jason Wright, who HAS been modeling what evidence for extraterrestrial civilizations and their technology MIGHT look like if it showed up in the Kepler data. This was in an effort to see if any of the observations might fit into that realm of actual research. Jason talks about the topic here — it’s worth a read.

If such a civilization had built a Dyson sphere (a star-girdling artifact first written about by science fiction master Olaf Stapledon), it might be detectable in some wavelength ranges of light (particularly if there were any communications arrays, for example). And, of course, a star-girdling sphere or ringworld might block starlight in a peculiar pattern. And, if that’s what’s happening at this star, it’s still a good idea to make sure we know what the naturally occurring causes of variability are before making assumptions about the alien technological possibilities.

Of course, that’s an entirely different story than what’s been playing out in the press over this whole story. In good analysis, scientists will look at “off the bell curve” ideas in order to understand what they’re seeing. It doesn’t make those theories correct. It just means the team is being thorough. I do think that the idea of searching for ET civilizations is inherent in the search for other planets, and someday astronomers WILL come across some data that can’t be explained by any other means. But, before you get to aliens, you DO have to rule out the other possibilities first.

OMG

Now, I know that suggesting alien technology is WAY more interesting than some mundane thing like actually spending time actually like, you know, studying the star and making precise measurements of the light dips. And, why mess with dust clumps (which are known and proven to exist around young stars that are forming planets) when the idea of ALIEN MERRY-GO-ROUNDS!!! OMG!!! is so much more enticing.

Trust me. The idea of comets smashing into each other while orbiting a distant star is actually way more cool than you think. The fact that they may well exist there tells us a LOT about that star and the clouds of gas and dust that orbit it. There’s action going on there, but it’s not harboring aliens. No flux of radio emissions from them has been detected, and until there’s something more substantial than somebody surmising that there’s a Dyson sphere out there, it’s really a good idea to stick to Occam’s Razor here: among competing hypotheses, the one with the fewest assumptions should be selected.

In other words, the explanation that is likely the most true is the one that requires the least fantastical assumptions to be made.

In the meantime — keep an eye out over the next two years — the same groups of observers who found the dips in the first place are going to keep looking at this star. More data is always good to have, and should give everybody a much better idea of the spacing of the clumps of dust and cometary debris they think are causing the dips in stellar brightness.

If you don’t believe me, check out what my friend Phil Plait has to say on the same story. He’ll give you the straight story, too. Like me, he thinks that searching for alien civilizations is a cool idea, and searches like this one could turn up some kind of artifact some day. But, probably not this one. Still, it’s a cool finding — comets and all!