Tabby's star just a star, probably not an alien power source

KIC 8462852.
KIC 8462852. Photo credit: NASA

A star some had suggested could be home to a powerful alien civilisation is probably just surrounded by dust, new research has found.

KIC 8462852 is a star in the constellation of Cygnus, about 1280 light years from Earth.

It's better known as 'Tabby's star', named after astronomer Tabetha Boyajian, who in 2015 noticed its light was fluctuating strangely.

Normally that would be a sign of a planet, but the evidence didn't match up - and nor did other theories, such as a comet swarm.

There was soon speculation the star could be surrounded by what's known as a Dyson sphere -an artificial structure designed to capture the star's energy for use by an advanced alien civilisation. Ms Boyajian was sceptical, but open to the idea.

"Extraordinary claims require extraordinary evidence, and it is my job, my responsibility, as an astronomer to remind people that alien hypotheses should always be a last resort."

During a presentation in early 2016, Ms Boyajian said her favourite theory was that she "had just witnessed an interplanetary space battle and the catastrophic destruction of a planet.

"Now, I admit that this would produce a lot of dust that we don't observe. But if we're already invoking aliens in this explanation, then who is to say they didn't efficiently clean up all this mess for recycling purposes?"

But recent data collected by Ms Boyajian and her team at Louisiana State University will leave many disappointed. It's just dust, not an alien megastructure.

"From what we can assume, a megastructure would be a solid body, not capable of producing the colour dependence we observe," she told CNET.

"Dust is the most likely the reason why the star's light appears to dim and brighten."

It's the second disappointment for alien hunters in the past month. In December, the first confirmed interstellar asteroid was analysed, and found to show no signs of being artificial in origin.