Astronomers spotted colliding neutron stars that may have formed a magnetar

A surprisingly bright cosmic blast might have marked the birth of a magnetar. If so, it would be the first time that astronomers have witnessed the formation of this kind of rapidly spinning, extremely magnetized stellar corpse.

That dazzling flash of light was made when two neutron stars collided and merged into one massive object, astronomers report in an upcoming issue of the Astrophysical Journal. Though the especially bright light could mean that a magnetar was produced, other explanations are possible, the researchers say.

Astrophysicist Wen-fai Fong of Northwestern University in Evanston, Ill., and colleagues first spotted the site of the neutron star crash as a burst of gamma-ray light detected with NASA’s orbiting Neil Gehrels Swift Observatory on May 22. Follow-up observations in X-ray, visible and infrared wavelengths of light showed that the gamma rays were accompanied by a characteristic glow called a kilonova.

Kilonovas are thought to form after two neutron stars, the ultradense cores of dead stars, collide and merge. The merger sprays neutron-rich material “not seen anywhere else in the universe” around the collision site, Fong says. That material quickly produces unstable heavy elements, and those elements soon decay, heating the neutron cloud and making it glow in optical and infrared light (SN: 10/23/19).

A new study finds that two neutron stars collided and merged, producing an especially bright flash of light and possibly creating a kind of rapidly spinning, extremely magnetized stellar corpse called a magnetar (shown in this animation). 

Astronomers think that kilonovas form every time a pair of neutron stars merge. But mergers produce other, brighter light as well, which can swamp the kilonova signal. As a result, astronomers have seen only one definitive kilonova before, in August 2017, though there are other potential candidates (SN: 10/16/17).

The glow that Fong’s team saw, however, put the 2017 kilonova to shame. “It’s potentially the most luminous kilonova that we’ve ever seen,” she says. “It basically breaks our understanding of the luminosities and brightnesses that kilonovae are supposed to have.”

The biggest difference in brightness was in infrared light, measured by the Hubble Space Telescope about 3 and 16 days after the gamma-ray burst. That light was 10 times as bright as infrared light seen in previous neutron star mergers.

“That was the real eye-opening moment, and that’s when we scrambled to find an explanation,” Fong says. “We had to come up with an extra source [of energy] that was boosting that kilonova.”

Her favorite explanation is that the crash produced a magnetar, which is a type of neutron star. Normally, when neutron stars merge, the mega-neutron star that they produce is too heavy to survive. Almost immediately, the star succumbs to intense gravitational forces and produces a black hole.

But if the supermassive neutron star is spinning rapidly and is highly magnetically charged (in other words, is a magnetar), it could save itself from collapsing. Both the support of its own rotation and dumping energy, and thus some mass,

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Two Massive Pieces Of Space Junk At ‘Very High Risk’ Of Colliding Thursday Evening

UPDATE: On Wednesday, updated data from LeoLabs predicts the two objects will come within just 12 meters of each other, twice as close as previously estimated.

A defunct Russian satellite and a spent Chinese rocket just floating around high over Earth could smash into each other within a few days, potentially creating a big mess in orbit with potentially dire long-term consequences.

LeoLabs, which tracks space debris, put out the alert on Tuesday warning that the two large hunks of junk will come within 25 meters of each other and have up to a twenty percent chance of colliding Thursday evening.

That’s considered way too close for comfort by space standards. The two objects have a combined mass of 2,800 kilograms and if they were to smash into each other, the “conjunction” could create thousands of new pieces of space junk that would put actual functioning satellites at risk.

Astronomer Jonathan McDowell, who keeps a close eye on objects in orbit, identified the old crafts as the Russian Parus navigation satellite that launched in 1989 and a Chinese ChangZheng-4c rocket stage that’s been adrift since 2009.

McDowell noted on Twitter that the altitude where the objects are located is also frequented by “lots of large objects” and that a collision would be “very bad.”

There has been a growing concern among astronomers and others in the space community lately about the accelerating proliferation of space debris. The more objects there are orbiting Earth, the higher the risk of collisions. More collisions also increases the risk of future collisions further in a feedback loop that could end in a scenario known as “Kessler Syndrome,” in which access to space becomes too dangerous.

This could be jumping the gun a bit, but with thousands of satellites headed to orbit as part of SpaceX’s Starlink and other planned mega-constellations, this week’s alert could be something that becomes routine in the not too distant future.

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2 large pieces of space junk have a ‘high risk’ of colliding

Two pieces of space junk, each about the weight of a compact car, are predicted to have a close encounter tonight some 620 miles above Earth. If they collide—and experts are putting the odds at greater than 10 percent—the smashup would create a cloud of debris that could jeopardize other satellites and spacecraft for decades.

The two objects are a defunct Russian navigation satellite launched in 1989 and a spent Chinese rocket part from a 2009 launch. Calculations by LeoLabs, a California-based company that tracks objects in low-Earth orbit, peg the moment of closest approach at 8:56 p.m. ET on October 15 above the southern Atlantic Ocean, just off the coast of Antarctica. The combined mass of the two objects is about 6,000 pounds, and their relative speed will be about 33,000 miles an hour, according to LeoLabs.

If the two objects don’t collide it will be another near-miss—one of a handful that happen every year—with the objects likely getting within about 40 feet of one another, by LeoLabs’ estimate. These two pieces of space junk are particularly large, however. The third stage of the rocket—the upper part that separates from lower stages and flies all the way into orbit—measures about 25 feet long. The satellite measures 16 feet long, with a boom used to stabilize the spacecraft extending almost 56 feet.

If they smash head-on, it would create two big clouds “that will spread out into a shell of debris around the Earth,” says LeoLabs CEO Daniel Ceperley. And because of the objects’ altitude, the debris would “be up there for centuries” before burning up in the atmosphere.

The long boom on the Russian satellite also raises the possibility of a glancing blow rather than a head-on collision. The results of an impact like that are harder to predict, says Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

Still, “there’s no threat to the Earth,” McDowell says. “These will be small debris pieces that will completely burn up in the atmosphere. Most of them aren’t going to come down for decades anyway, and when they do, they’ll completely burn up.”

The International Space Station (ISS) is also in no immediate danger. The ISS orbits at an altitude of about 250 miles, “safely below” the altitude where the debris would potentially be unleashed. There would “probably not be a big risk to the ISS in the near term,” McDowell says. But over many years, bits of debris could drift down to the space station’s orbit. “It would increase the amount of ‘rain’ failing on it,” he says.

The ISS has had to maneuver out of the way of space debris to avoid damage on three occasions this year, including a near miss less than a month ago.

The potential debris field would pose a danger to any craft passing through, including satellites on their way up to a higher geosynchronous orbit (about 22,000 miles above Earth), or any satellites above that are being deorbited into

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