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Planet-forming disks with misaligned rings discovered in multi-star system



Sept. 3 (UPI) — Astronomers have discovered misaligned rings within the planet-forming disk surrounding a faraway, triple-star system, according to a study published Thursday in the journal Science.

Scientists suspect the disk was disrupted by the gravitational pull from one of the three stars.

The trio of stars that form GW Orionis are located approximately 1,300 light-years from Earth. The system is noted for its giant protoplanetary disk.

Recently, astronomers were able to confirm the disk’s misalignment using observations by the Atacama Large Millimeter/submillimeter Array, a powerful observatory in Chile.

By studying how the massive planet-forming disk came to be misaligned, researchers hope to better understand how planets around multi-star systems form and evolve.

“The idea that planets form in neatly-arranged, flat disks around young stars goes back to the 18th century and Kant and Laplace,” Stefan Kraus told UPI in an email.

“The GW Ori images reveal an extreme case where the disk is not flat at all, but is warped and has a misaligned ring that has broken away from the disk and that is now precessing around the stars,” said Kraus, an astronomer at the University of Exeter.

Kraus and his research partners suggest GW Orionis and its off-kilter protoplanetary disk rings are interesting for a few different reasons. For one, the system is rare.

While many exoplanets have been found orbiting binary star systems, very few have been found circling systems with three or more stars. What’s more, exoplanets surrounding multi-star systems typically orbit very close to their host stars.

“The disk structures in GW Orionis, on the other hand, extend out to 400 [astronomical unites], or more than 10-times the separation of Neptune from the sun,” Kraus said. “So the system has the potential to form circumtriple planets on very wide orbits.”

Researchers were able to identify the misalignment of the disk’s rings by analyzing the scattered light and shadows cast by the differently inclined rings of dust.

“Shadows on disks have been observed before, but to my knowledge this is the first case where we resolve the ring casting the shadow,” Kraus said. “Also, one is used to seeing ‘straight’ shadows on disk — here, we have the extraordinary case that the shadow apparently ‘changes’ direction due to the strong curvature in the inner warped region of the disk.”

Scientists ran simulations to better understand how the triple-star system’s disk came to be warped and misaligned. The simulations suggest the gravitational torque exerted by the three stars created a tearing effect in the ring.

As a result of the tearing effect, scientists predict GW Orionis will birth a variety of exoplanets with oblique orbits — orbits askew from the equators of their host stars.

“We predict that many planets on oblique, wide-separation orbits will be discovered in future planet imaging surveys,” Kraus said.

Thanks to the analysis by Kraus and his colleagues, astronomers now know the 3D orientation of the system’s protoplanetary disk, as well as the properties of all three stars, making GW Orionis an ideal model for the study of exoplanet formation.

“This makes GW Ori a benchmark for studying body-disk interactions in general, which will advance our understanding of planet formation as well,” he said.

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NASA’s OSIRIS-REx touches down on asteroid Bennu to nab sample



Oct. 20 (UPI) — NASA’s OSIRIS-REx touched down on asteroid Bennu on Tuesday evening in a mission to scoop a sample of rocks and dirt.

The spacecraft — the Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer — made soft contact with the asteroid at 6:12 p.m. EDT.

The historic “touch and go” event featured animation displaying OSIRIS-REx’s sample collection activities in real time. It takes time for real images of the touchdown to travel back to the Earth, so they won’t be released to the public until Wednesday.

The craft executed a series of maneuvers over the course of several hours before making soft contact with the surface of the asteroid to collect regolith, or rocks and dirt.

“It will be four and a half hours of anxiousness,” Beth Buck, OSIRIS-REx mission operations manager at Lockheed Martin Space, said in a news conference ahead of the event.

Buck made a comparison to the descent of a spacecraft on Mars, when there is typically “seven minutes of terror.”

The goal is to learn more about the solar system’s history and help “planetary defense” engineers with missions to protect earth from rogue asteroids. Bennu is believed to be a window into the solar system’s past since it’s a pristine, carbon-rich body carrying building blocks of both planets and life.

At around 1:50 p.m. EDT, the spacecraft left orbit around the asteroid before executing a series of burns to position itself over a sampling area nicknamed Nightingale.

Once in position, the craft began its approach to the asteroid at 5:50 p.m. EDT. It then spent about 15 seconds attempting to collect the regolith sample before backing away again.

The area, which is 52 feet in diameter, will make for a more demanding landing than expected, Kenneth Getzandanner, OSIRIS-REx flight dynamics manager at the NASA Goddard Space Flight Center in Maryland, said in the news conference.

The original mission called for a landing “zone” about 150% larger than Nightingale, at 82 feet, but that changed because Bennu was more rocky than expected.

The goal was to collect at least 1.7 ounces of fine-grained material, but the spacecraft can carry up to 4.4 pounds, Heather Enos, OSIRIS-REx deputy principal investigator at the University of Arizona said.

“I would love for that capsule to be completely full,” Enos said.

Though early images from the asteroid should hint at whether the mission succeeded, it will take engineers roughly 10 days to compare and analyze the mass before and after the maneuver to actually know how much dirt is inside the OSIRIS-REx.

If it failed, the spacecraft has enough fuel to attempt two more touch downs to collect material.

The spacecraft is expected to return to Earth, with the regolith sample from Bennu, in 2023.

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SpaceX scrubs Starlink launch until Thursday, if weather cooperates



Oct. 21 (UPI) — Just three days after sending 60 more Starlink satellites into orbit, SpaceX is aiming to launch another batch of broadband satellites into space from Florida.

If the weather cooperates, Thursday’s launch will be SpaceX’s 15th Starlink mission.

Liftoff had been scheduled for 12:29 p.m. EDT Wednesday aboard a Falcon 9 rocket at Launch Complex 40 at Cape Canaveral Air Force Station, but controllers scrubbed the launch due to weather and rescheduled for 12:14 p.m. on Thursday.

With a launch Sunday, SpaceX increased the size of their Starlink constellation to nearly 800 satellites. The 15th mission will see another 60-odd satellites join the network.

“The goal of Starlink is to create a network that will help provide Internet services to those who are not yet connected, and to provide reliable and affordable Internet across the globe,” according to the Kennedy Space Center.

Weather for Wednesday’s planned launch had looked so-so and the Space Force’s 45th Weather Squadron predicted a 60 percent chance of favorable conditions.

“A mid-level inverted trough and associated easterly wave currently across the Bahamas will meander into the state over the next few days, bringing enhanced moisture, cloud cover, and instability with a higher coverage of showers and storms,” Space Force forecasters wrote.

They said Thursday’s forecast looks quite similar to Wednesday’s.

Earlier this month, SpaceX founder and CEO Elon Musk tweeted that Starlink’s constellation was big enough to begin beta-testing the Internet service system in both the United States and southern Canada.

SpaceX has already offered Starlink Internet services to emergency responders in wildfire-stricken areas of Washington State.

Washington’s Hoh tribe is also using the Internet service to provide their members online education and telehealth services.

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Chernobyl-level radiation harms bumblebee reproduction



Oct. 21 (UPI) — Bees are more sensitive to radiation than scientists thought. Scientists found the reproduction rates of bumblebees declined significantly when exposed to Chernobyl-level radiation.

The research, published Wednesday in the journal Proceedings of the Royal Society B: Biological Sciences, suggests radiation in Ukraine’s Chernobyl Exclusion Zone could impair pollination services, triggering wider ecological consequences than previously estimated.

Humans are not allowed to live in the Chernobyl Exclusion Zone, the disaster area more directly impacted by the 1986 nuclear accident, the worst in history. However, the destroyed nuclear reactors are surrounded by forests that are populated by robust populations of birds, bears, bison, lynx, moose, wolves and more.

Efforts to gauge the effects of radiation contamination on insects have yielded mixed results in the past. While some studies have suggested insects are relatively radiation-resistant, others have demonstrated significant impairment.

When researchers exposed bumblebees in the lab to radiation dose of 100 µGyh-1, an amount approximating exposure inside the Chernobyl Exclusion Zone, reproduction rates among the bees dropped between 30 and 45 percent.

Researchers found a direct correlation between the size of the radiation dose and reproduction rate declines. Lower levels of radiation had a smaller effect, while larger doses yielded greater declines.

Scientists were surprised to find they were able to detect reproductive rate declines at very small levels of radiation exposure.

“Our research provides much needed understanding as to the effects of radiation in highly contaminated areas and this is the first research to underpin the international recommendation for the effects of radiation on bees,” lead study author Katherine Raines, environmental scientist at the University of Stirling in Scotland, said in a news release.

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