Friday 28 October 2016

Scientists Aim Largest Telescope Possible At 'Alien Megastructure' Star

Early Thursday morning, a new and powerful effort was underway to explore a mystery 1,500 light-years away. West Virginia's Green Bank Telescope was hard at work, sucking up information about a strange winking star. The giant radio telescope is the biggest of its kind, with a 330-foot-wide parabolic dish, making the device the largest steerable telescope on Earth. The Green Bank Telescope is tucked
away among the sleepy Allegheny Mountains in West Virginia, where state and federal laws enforce an electromagnetic quiet zone to keep interference to a minimum. For astronomers and space buffs, the star in question, KIC 8462852, has been anything but quiet. The new Green Bank Telescope effort, announced Tuesday, is the deepest probe of KIC 8462852 yet, part of University of California at Berkeley's Breakthrough Listen program - the $100 million project backed by Russian billionaire Yuri Milner with support from Stephen Hawking.

"We can look at it with greater sensitivity and for a wider range of signal types than any other experiment in the world," said Andrew Siemion, of Berkeley's Search for Extraterrestrial Intelligence Research Center, in a news release.

Last year, scientists led by Louisiana State University astronomer Tabetha S. Boyajian published a lighting rod of a study: Observations taken from the Kepler spacecraft revealed that KIC 8462852, also known as Tabby's Star after Boyajian, did not behave like other stars.

Specifically, Tabby's Star flickered.

The star's flux - its brightness - dipped by as much as a fifth over the course of Kepler's observations, The Washington Post reported last October. By way of comparison, should a planet as huge as Jupiter swoop in front of KIC 8462852, in a move known as a transit, such a gas-giant-size journey would dim the star only by 1 percent. (Tabby's Star is also known as the WTF Star - for Where's the Flux. Though, we suspect the abbreviation could stand for something else too.)

What's more, the extreme dimming did not follow a constant pattern. The dips varied in duration, as though the star were blinking fast and slow. For a star of its size and age, this was unprecedented behavior.

If you are familiar with what happens when a space-science mystery meets an unprecedented observation, you might be able to guess where speculation went. Even some astronomers, meticulous by profession, were not afraid to float the a-word: Could the dimming, however unlikely, be signs of alien life?

"Aliens should always be the very last hypothesis you consider," Penn State University astronomer Jason Wright told the Atlantic magazine, "but this looked like something you would expect an alien civilization to build."

One popularly cited idea was a Dyson structure, a hypothetical device that could collect energy from a sun using a network akin to orbiting solar panels. Tabby's Star gained yet another nickname, the "alien megastructure" star.

When asked during a live chat Wednesday afternoon about the meaning of a non-natural source of flicker, Siemion said that "the implications could be as far-reaching and awe-inspiring as could possibly be imagined," paraphrasing "Contact."

To be clear, scientists remained incredibly skeptical that the dimming had a technological cause. "I don't think it's very likely - a one in a billion chance or something like that," said Berkeley SETI's chief scientist, Dan Werthimer, on Tuesday. That there was a star acting in an unprecedented way was itself not unprecedented, as the 1967 discovery of pulsars showed.

Since the fall of 2015, various scientists, astronomers and SETI researchers have pointed a host of devices at Tabby's Star. In November, the SETI Institute revealed it had failed to detect narrow or broadband radio signals using the 42 antennas of the Allen Telescope Array, near San Francisco.

"So far," as The Post's Rachel Feltman wrote at the time, "we've got nothing."

Later that month, Iowa State University scientists argued that a natural cause, a collection of comets, could explain the winks of Tabby's Star. That explanation has been a source of debate, leading one astronomer to declare in January that all hypotheses published thus far had been unsatisfactory. Where's the Flux, indeed.

"It's been looked at with Hubble, it's been looked at with Keck, it's been looked at in the infrared and radio and high energy, and every possible thing you can imagine, including a whole range of SETI experiments," Siemion said. "Nothing has been found."

Enter the Green Bank Observatory. Pointed at Tabby's Star, the telescope has embarked on a project to comb hundreds of millions of individual radio channels. The telescope's observations Thursday were associated with human technologies, exploring a spectrum from 1 to 12 gigahertz, which would include some cellphone operating frequencies up to those of television satellites. At the end of the three eight-hour nights, spaced out over two months, the astronomers will have collected about a petabyte of data (a million gigabytes, or the data equivalent to what 20 million four-drawer filing cabinets can hold).

If there are two things for certain about KIC 8462852, it is that the star remains fascinating, and that scientists 1,500 light-years away are committed to taking the hardest look at Tabby's Star they can.

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