Tuesday, January 19, 2016

The "alien megastructure" star is back, and even more mysterious than before

After months of analysis, including looking through "glass plate" records dating back more than a century, scientists have ruled out comets accounting for the extreme light fluctuations. But what they discovered is even more puzzling.

Artist's rendering of a hypothetical Dyson Sphere.

by S. Alex Martin

Remember the "alien megastructure" star? The weird one whose light dipped by 20% at irregular intervals and the scientific consensus came to be clouds of orbiting comets?

After months of examinations, the cloud of comets has been ruled out as “completely implausible” given the size and density required for the swarm of comets to be in order to cause this phenomenon. According to Bradley Schaefer, of Louisiana State University, it would have to be “648,000 comets, each 200 kilometers [120 miles] wide.”

Schaefer and other researchers went back through records dating through the past century, located the star, and, after thorough analysis, made a startling discovery: KIC 8462852 has decreased in overall luminosity by about 20% over the past century, dimming by roughly 0.193 magnitudes.

Luminosity measurements recorded over the course of a century.
(Source: Bradley Schaefer, arXiv.org)

Now, although stars do go through cycles throughout their lives, overall luminosity essentially doesn’t change, especially not by such a huge margin. And even if it were a cloud of dust or asteroids or comets, you’d expect the luminosity to increase, because gravity would clump things together, therefore creating more unobstructed space for light to shine through. In fact, there would need to be 10,000 to 10,000,000 times MORE dust in the same region today than a century ago to account for the dimming.

A cloud of comets has been dismissed as the cause of light fluctuations

So is a Dyson Sphere--and thus, intelligent life--back on the table?

Schaefer remains skeptical, as we all should be, “as he thinks aliens wouldn’t be able to build something capable of covering a fifth of a star in just a century.” There’s also the issue that if there was a structure, we should be able to detect signatures from across narrow microwave and short-wave infrared bands--and we’re not.

Let’s go back to Schaefer’s point about a century being too short a time span to construct a Dyson Sphere (as this megastructure is often called, one which surrounds a star to capture and store energy). If an intelligent civilization more advanced than us is capable of constructing a Dyson Sphere-like structure, would it be so implausible to think that they could have the capability to construct it relatively quickly?

I’ll leave that up to you. For now, comets seem to be out of the question, and the mystery of KIC 8462852 remains with no plausible explanation.

[Cited Article Source: New Scientist]

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