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Wednesday, 27 January 2016

Tabby's star: The mystery deepens

'Tabby's star' is an oddly unassuming name for a star that is so mysterious, and has attracted so much wild speculation, but it seems to have stuck. 
In case you've not been obsessively following the astronomy news in the way way I do, Tabby's star (real name KIC 8462852, but nicknamed for the lead author on the paper that first noted it's strangeness) flickers in an unusual way: Most stars that change in brightness are naturally variable, or are orbited by planets that block out some of the light as they rotate between the star and Earth. Both cases produce a recognisable kind of flicker, with a definite pattern to it. Tabby's star seems to flicker in a random way (I've mentioned it before in this post and this post), and to make it even odder as search through historical data shows it has been steadily dimming overall for over a century. Of course, one explanation put forwards for this strange behaviour is aliens - aliens get invoked fairly quickly when naural explanations don't pan out, because aliens could be up to almost anything.  

It's not Starkiller Base from Star Wars, ok? Unless the universe is even weirder than I think, in which case it is.

But this star's odd behaviour does sort of match what we'd expect to see if an alien race were building swarms of solar panel power stations around its star. Other, much more testable and likely explanations include huge swarms of comets orbiting the star, and a new kind of starspot (like our Sun's sunspots, but much bigger), but none has really fit the data.

Above: The ISS and many other spacecraft already use solar panel powerplants, although the scale of the energy collecting around Tabby's star would need to be massivey bigger to make it dim so much. Image courtesy of NASA
Right now the Sun is between Tabby's star and us, but in a few months it will become viewable again, and astronomers are making plans to settle the mystery for good.
“If we could catch it in the act of dimming again, that would really help,” Penn State University’s Jason Wright said. Although two independent surveys haven’t turned up any evidence of extraterrestrial technology, UC Berkeley’s SETI program is now working with the billionaire-backed alien hunting initiative Breakthrough Listen, and plans to conduct a very sensitive broadband sweep of the star’s neighbourhood.
Follow-up is proceeding on other fronts as well: Big optical telescopes are watching the star, waiting for another dimming event to take place. Once dimming begins, telescopes outfitted with spectrographs will begin monitoring the various wavelengths of emitted by Tabby's star, Wright told earlier this year.
"That'll tell us what that material is that the starlight is being filtered through," he said. "It'll tell us if maybe we're looking at ordinary astrophysical dust; it'll tell us if we're looking at gas."  The Kepler space telescope will also be make more observations of the star, in 2017.

Keep an eye on Jason Wrights's blog for more updates.

Elsewhere in the Universe:

Mars rover works through winter

China invites public to access its Moon exploration data

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