Three months ago, news broke that a giant "alien megastructure" could exist around a bizarre-looking star 1,500 light-years away. While the prospect of aliens was first launched by Penn State
astronomer Jason Wright, almost everyone in the astronomy community
agreed that the chances that this was the case were "very low."
Now, the latest investigations into this strange star by Louisiana State University astronomer Bradley Schaefer have reignited the alien theory, New Scientist reported
.
What makes this star,
KIC8462852, so bizarre is the drastic changes in light we see from it
over time. Many stars experience temporary fluctuations in brightness,
increasing and decreasing in luminosity over time, but KIC8462852's
changes are severe by comparison.
Between 2009 and 2013,
astronomers using the Kepler space telescope discovered that it would
sometimes lose up to 20% of its brightness. What's more, the changes
didn't follow any obvious pattern.
That would suggest something
gigantic must be blocking the light at random times, meaning that it
couldn't be a planet or other regular orbiting object because that would
generate a distinct pattern of dimming light. It must be something that
changes shape over time, thereby blocking different levels of light at
random intervals.
Surprise: It's probably not comets
An alien megastructure, called a Dyson swarm,
was suggested as one explanation for what scientists have observed, but
the most likely reason astronomers came up with was comets — a giant
family of them.
But Shaefer says not so fast.
"The comet-family idea was reasonably put forth as the best of the proposals, even while acknowledging that they all were a poor lot," Schaefer told New Scientist. "But now we have a refutation of the idea, and indeed, of all published ideas."
To make his discovery, Schaefer had to dig deep down into the
astronomy archives at Harvard. It turns out, astronomers have data on
KIC8462852 dating back as far as 1890.
By analyzing over 1,200 measurements of this star's brightness taken
from 1890 through 1989, Schaefer found that the irregular dimming of
KIC8462852 has been going on for over 100 years. Schaefer published his
findings in the online preprint server arXiv.org.
What's more, he explains in his paper that this "century-long dimming
trend requires an estimated 648,000 giant comets (each with 200 km
diameter) all orchestrated to pass in front of the star within the last
century," which he said is "completely implausible."
So what is it?
By killing the comet theory, Schaefer has brought us one step closer to finding out what is really happening around KIC8462852.(NASA/JPL-Caltech) An artist's concept of gas-giant planets in a dusty solar system, similar to how HD 95068 could look.
At the same time, he's also reignited the possibility that the source could be an alien megastructure that an advanced alien civilization has been slowly building over time. One thing's certain for Schaefer: The bizarre dimmings are probably caused by a single, physical mechanism that's undergoing some type of ongoing change.
"The century-long dimming
and the day-long dips are both just extreme ends of a spectrum of
timescales for unique dimming events, so by Ockham's Razor, all this is
produced by one physical mechanism," Shaefer said in his paper. "This
one mechanism does not appear as any isolated catastrophic event in the
last century, but rather must be some ongoing process with continuous
effects."
Schaefer isn't the only one
interested in learning more about KIC8462852. Late last year, astronomer
Doug Vakoch and his team at the new organization called SETI (Search for Extraterrestrial Intelligence) International — not to be confused with the SETI Institute — went hunting for aliens around KIC8462852.
They searched for signals that
an alien civilization might be beaming toward Earth either in radio or
visible wavelengths, but ultimately they came up empty handed. So, if it
is aliens, then they're being awfully quiet.
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