Spin to survive: How 'Saturn on Steroids' keeps from self-destructing

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Scientists are one step closer to understanding a mystery of the Milky Way.

In 2007, data showed that a young star about 400 light years away from our solar system was blinking. It was being covered, uncovered and covered again in what astronomers call a "series of complex eclipses."

The eclipses told astronomers that something was orbiting the young star, and that the something was very large.

Eric Mamajek first saw the 2007 data on Dec. 11, 2010, when he was a young professor of physics and astronomy at the University of Rochester. "It was one of those great times one enjoys as a scientist where one realizes that one is seeing something new and bizarre that no person has seen before," he told NPR via email.

"You realize that you need to make sense of it and report it to the rest of the world," he said.

Mamajek did just that, and in 2012, he and colleagues published a paper announcing what they thought was causing what he calls "the weird eclipse."

It was an enormous ring system swirling around a planet.

"This planet is much larger than Jupiter or Saturn, and its ring system is roughly 200 times larger than Saturn's rings are today," Mamajek said at the time.

"You could think of it as kind of a super Saturn."

Or, as others have put it, Saturn on steroids.

Mamajek and his co-author on the 2012 paper, Matthew Kenworthy of the University of Leiden in the Netherlands, created an animation showing how the massive ring system, called J1407b, could eclipse the star, unromantically named J1407.

But there were still many questions about the ring system, one of which had to do with its enormous size. Last year, Mamajek and Kenworthy published another paper that showed the system consists of more than 30 rings, each of them tens of millions of kilometers in diameter. (Kenworthy also made this crazy image showing what J1407b would look like from Earth if it replaced Saturn in our solar system.)

Which led some astronomers to wonder how something so large could hold together as it swung around its star.

The answer might have something to do with spin, according to a new paper by Kenworthy and a colleague in Japan, Steven Reider, published this week in the journal Astronomy & Astrophysics.

According to the paper, the key to why spin is so important begins with orbits. Not all orbits are circles. The Earth, for example, takes a slightly oval-shaped path around the sun, which means in January, the two are at their closest point.

The same is true of J1407b — because it doesn't orbit in a circle, there is one point when the massive spinning disc of debris that makes up its rings comes closest to its star. And at that moment, the disc is at the most risk for breaking apart.

But it doesn't break apart, and the reason, the authors of the new paper think, is that J1407b is spinning backward. Don't worry, you don't have to try to imagine it — Reider made a video simulation of their theory.

Beware, about 15 seconds into the video, things get wild and destructive in the right panel.

As you can see, when the rings spin clockwise around the planet, they are torn apart as the system passes the star. But when the rings spin counterclockwise, they survive.

"It seems to be a reasonable solution," says Mamajek, who recently became deputy chief program scientist for the NASA Exoplanet Exploration Program at the Jet Propulsion Laboratory. "These simulations are the first to clearly test this [retrograde spin] idea."

Studying J1407b "is science in slow motion," he says. It's been almost a decade since the initial data was collected, and it takes about 11 years for the ring system to travel just once around its star.

But, he says, amateur astronomers with backyard telescopes can help. He and others, have enlisted the help of the American Association of Variable Star Observers, a citizen science organization, to fill in gaps in the data collected by professional telescopes. Amateur stargazers have uploaded dozens of images to plot the brightness of the star over time.

Copyright 2016 NPR. To see more, visit http://www.npr.org/.


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