A seriously strange star

Comets can't explain weird 'alien megastructure' star after all | New Scientist

I think I have resisted, until now,  posting about the star that might have alien megastructures around it, as I always thought a mundane explanation would be established soon enough.

But with this news, of the star dimming 20% over a century, it is time to me to admit that this is a seriously strange star with something very odd about it:

To confirm the fade was real, Schaefer went to Harvard to look at the
original photographic plates and inspected them by eye for changes, a
skill few astronomers possess these days. “Since no one uses
photographic plates any more, it’s basically a lost art,” says Wright.
“Schaefer is an expert at this stuff.”

Schaefer saw the same century-long dimming in his manual readings,
and calculated that it would require 648,000 comets, each 200 kilometres
wide, to have passed by the star – completely implausible, he says.
“The comet-family idea was reasonably put forth as the best of the
proposals, even while acknowledging that they all were a poor lot,” he
says. “But now we have a refutation of the idea, and indeed, of all
published ideas.”

“This presents some trouble for the comet hypothesis,” says Boyajian.
“We need more data through continuous monitoring to figure out what is
going on.”

What about those alien megastructures? Schafer is unconvinced. “The
alien-megastructure idea runs wrong with my new observations,” he says,
as he thinks even advanced aliens wouldn’t be able to build something
capable of covering a fifth of a star in just a century. What’s more,
such an object should radiate light absorbed from the star as heat, but
the infrared signal from Tabby’s star appears normal, he says.

“I don’t know how the dimming affects the megastructure hypothesis,
except that it would seem to exclude a lot of natural explanations,
including comets,” says Wright. “It could be that there were just more
dimming events in the past, or that astronomers were less lucky in the
past and caught more dimming events in the 1980s than in the 1900s. But
that seems unlikely.”

There’s no doubt KIC 8462852 is behaving strangely, so something must
be responsible, says Schaefer. “Either one of our refutations has some
hidden loophole, or some theorist needs to come up with some other
proposal.”