Dienstag, 10. Januar 2017 - 07:50 Uhr

Astronomie - Ein heller neuer Stern (KIC 9832227)wird am Himmel in fünf Jahren sich als Nova zeigen, sagen Astronomen




A team of astronomers is making a bold forecast: A binary star found in the summer constellation Cygnus the swan will burst into a red nova sometime in 2022.

When the two stars in the binary system crash into one another, they will create a brick-red beacon so bright that sky gazers will see it with the naked eye, Larry Molnar of Calvin College said Friday at the American Astronomical Society meeting in Grapevine, Tex.

As the constellation Cygnus glides gracefully along the Milky Way every late spring and summer, the cosmic bird’s left wing houses a faint binary star called KIC 9832227. The two stars spinning around one another are merging, on a path to an explosion that will result in a red nova, said Molnar and his colleagues.

For KIC 9832227, the orbital period is currently just under 11 hours, he said, and “as that period gets shorter, we infer that the separation between the stars is getting smaller. Hence they are spiraling in together.”

The astronomers first presented this star’s red nova prognostication at the January 2015 American Astronomical Society meeting, but the predictions teemed with unknowns. “The core of this [new] scientific presentation is that we have done two strong tests and that our hypothesis [from 2015] is holding up,” he said. “We have eliminated the alternative interpretations and we have also refined the predicted time to 2022, plus or minus one year.”

To refine the prediction, the astronomers examined a recent red nova — a star called V1309 Scorpii, discovered in September 2008. Using V1309 Scorpii research (conducted by Polish astronomer Romuald Tylenda) as a sort of cosmological blueprint, Molnar and colleagues found similar characteristics — from before the earlier explosion occurred.

Like the current candidate, V1309 Scorpii was a contact binary star and — similarly — its orbiting period (the time it took for the two stars in the binary system to spin around one another) decreased. Scientists had noted a changing light curve, all evidence of impending eruption.


This quest to comprehend red novas began when Molnar and then-Calvin College student Daniel Van Noord attended a presentation by astronomer Karen Kinemuchi of Apache Point Observatory in New Mexico, that asked if KIC 9832227 was a pulsing or binary star. Van Noord, who has since graduated, began dedicated observations at the Calvin observatory, where he found the orbital period shrinking.

The two spinning stars share a communal atmosphere “like two peanuts sharing a common shell,” Molnar said.

Beyond what humans can see with the unaided eye, KIC 9832227 is currently a 12th magnitude object, which means it's pretty dim. When it explodes sometime around 2022, “we expect it will reach second magnitude at the brightest,” Molnar said, where it will be among the brighter stars in the sky.

“We truly favor the merger hypothesis. … Now is the time to broaden our work and study the system more fully to … know what leads to a stellar explosion,” Molnar said. “Like many science stories, this one is gradually unfolding.”

Quelle: The Washington Post



Colliding stars will light up the night sky in 2022

GRAPEVINE, TEXAS—A team of astronomers is making a bold prediction: In 2022, give or take a year, a pair of stars will merge and explode, becoming one of the brightest objects in the sky for a short period. It’s notoriously hard to predict when such stellar catastrophes will occur, but this binary pair is engaged in a well-documented dance of death that will inevitably come to a head in the next few years, they say. The researchers began studying the pair, known as KIC 9832227, in 2013 before they were certain whether it was actually a binary or a pulsating star. They found that the speed of the orbit was gradually getting faster and faster, implying the stars are getting closer together. The pair is so close, in fact, they share an atmosphere (as in this artist’s conception of an unrelated stellar merger). KIC 9832227’s behavior reminded the researchers of another binary pair, V1309 Scorpii, which also had a merged atmosphere, was spinning up faster and faster, and exploded unexpectedly in 2008. Now, after 2 years of careful study to confirm the accelerating spin and eliminate alternative explanations, the team reported here today at the American Astronomical Society’s annual meeting that the pair will explode as a “red nova”—an explosion caused by a binary merging—in about 5 years’ time. The scientists will continue to monitor KIC 9832227 over the coming years to both firm up their prediction and learn more about how such a death spiral ends in a red nova. Amateur astronomers can study it, too, measuring how it fluctuates in brightness at an ever-increasing rate. And when it blows, we’ll all be able to enjoy the show.

Quelle: Science


Update: 10.01.2017


Scientists Predict Star Collision Visible To The Naked Eye In 2022


Scientists predict a star collision in the constellation Cygnus.


Scientists predict that a pair of stars in the constellation Cygnus will collide in 2022, give or take a year, creating an explosion in the night sky so bright that it will be visible to the naked eye.

If it happens, it would be the first time such an event was predicted by scientists.

Calvin College professor Larry Molnar and his team said in a statement that two stars are orbiting each other now and "share a common atmosphere, like two peanuts sharing a single shell."

They predict those two stars, jointly called KIC 9832227, will eventually "merge and explode ... at which time the star will increase its brightness ten thousand fold becoming one of the brighter stars in the heavens for a time." That extra-bright star is called a red nova. They recently presented their research at a meeting of the American Astronomical Society in Grapevine, Texas.

The team has monitored the star pair since 2013, and noticed that its orbital period was slowing down. That suggested it might be following a pattern scientists observed in another star, which exploded unexpectedly in 2008, the team said. They've now ruled out several other explanations for what could be causing the orbital period change, increasing confidence in the prediction.

"It will be a very dramatic change in the sky, as anyone can see it. You won't need a telescope to tell me in 2023 whether I was wrong or I was right," Molnar said at the presentation, according to National Geographic.

Todd Hillwig, an astronomer at Valparaiso University who was not involved in the prediction, told The Two-Way that he thinks "there's room for optimism, and room to say there are other things that could happen. But based on his data I think this looks like a very possible outcome."

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Hillwig explains that "we know quite a bit about the physics of stars," but "we don't know a lot at this point about exactly how these stars will merge when that happens, because we've only seen events like this after the fact."

That means knowing when a collision will take place provides a unique opportunity for scientists, Hillwig adds: "The possibility that we could see a system like this, and study it really well beforehand, and then see it happen has the potential to tell us a lot about the physics that's going on with these types of systems."

Quelle: npr