Tuesday 24 December 2019

Astronomers Identify 100 Stars That Went Missing Over Time, for Unknown Reasons

Astronomers are currently wrestling with something of a mystery. In 2016, a team of researchers in Sweden noticed that a star visible in an image from 1950 was no longer visible. Astronomers have started looking at other images from the last century, and they’ve found more missing stars, about 100 of them. A new paper speculates about the cause of this phenomenon. Could it be aliens? Probably not, but it’s still fun to think about. 

The image that kicked this survey off was captured on March 16, 1950 at the US Naval Observatory. The star cluster in question (seen above) is in the constellation Lupus. As you can see, a very bright star in the center of the image seems to have disappeared. The only known process by which a star could vanish is if it collapses into a black hole, but that comes after a very easily detectable supernova. 

The new paper points to 100 stars that have vanished under similarly mysterious circumstances — they are visible in observations from decades ago, but they aren’t there today. There’s no evidence they became black holes, so what’s going on?

The authors of the paper suggest these areas could be an excellent place to go looking for alien life. It stands to reason that if there’s no natural process by which a star can vanish, there may be an artificial one. Something like a Dyson sphere, which encloses a star to collect all of its energy output, could explain why these stars are no longer visible. This brings to mind observations of Boyajian’s Star, which dims at unusual intervals. Some have taken this as a sign that there could be “alien megastructures” orbiting it. If Boyajian’s Star vanished one day, that would certainly add weight to the proposals in the new paper. 

While it’s fascinating to speculate about aliens walling off stars with Dyson spheres, that’s probably not what’s happening. The study is currently only available on the arXiv preprint server. That means it has not undergone a rigorous peer review. 

If we assume the updated observations used in the study are accurate, there may still be non-alien explanations for the missing stars. The earlier images could have captured something in the foreground like a satellite or comet that looked like a star. There may also be something obscuring our view today that doesn’t appear in the visible spectrum. There could even be some natural process of which we are unaware that causes stars to vanish. 

This is something that warrants further investigation, of course, but it’s probably not aliens.

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