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Where did the interstellar object ‘Oumuamua come from? Its speed could tell us

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Astronomers will be able to figure out what kind of stars interstellar objects such as ‘Oumuamua come from, and therefore something about their compositions, based on their velocity as they enter our solar system, new research suggests.

So far, astronomers have discovered only two confirmed interstellar objects (ISOs) in our solar system, ‘Oumuamua and 2I/Borisov. They couldn’t have been more different from one another: ‘Oumuamua lacked any kind of cometary tail, whereas Borisov looked like a typical comet.

However, the properties of their home planetary systems are imprinted on both of them, said grad student Matthew Hopkins of the University of Oxford in England, who conducted the new research and presented it at the U.K.’s National Astronomy Meeting in early July.

“Because they come from other stars, their properties are going to correlate with those stars,” Hopkins told Space.com.

Though we’ve only spotted two ISOs to date, it’s expected that thousands of them are passing through our solar system at any given time, most too far away from us to be detected. However, most or all of those ISOs likely began life as comets around other stars, before an encounter with a Jupiter-sized planet, or perhaps a fly-by star, ejected them into interstellar space.

In our solar system, “for every one comet that Jupiter [and Neptune] pushed into the Oort Cloud, it completely ejected 10, and there are a trillion objects in the Oort Cloud,” said Hopkins. Doing the math, it is easy to come to the conclusion that ISOs “are the most numerous objects in the Milky Way galaxy.”

Moving groups of interstellar objects

Each star is moving around the galaxy at its own pace, and together they form moving groups that are related to their point of origin, which, in turn, corresponds with their intrinsic chemistry.

The stars with the most heavy elements, such as our sun, live in the “thin disk” of the galaxy, a plane in the spiral arms about 400 light-years thick. Surrounding it is the “thick disk,” which can stretch as high as 1,000 light-years above the plane of the galaxy and contains mostly older stars with fewer heavy elements.

The populations of stars belonging to each disk have different velocity distributions. Because the ISOs that they eject share a similar velocity as their parent star relative to the sun, they tend to stick to the same moving groups, but these moving groups criss-cross the sun’s path all the time.

“The sun is essentially running into them,” said Hopkins. This means that we should preferentially expect to see ISOs coming from the “solar apex,” which is the direction of the sun’s motion relative to other nearby stars.

“‘Oumuamua was very close to the solar apex,” Hopkins said. “Borisov was slightly farther away but still quite near [to the solar apex], and that’s where we expect most of them to come from.”

Coming from this direction means that they’ll make their closest approach to the sun, where they are easiest to detect, while they are in the Southern Hemisphere sky — the same sky that the new Vera Rubin Observatory will be surveying. It is expected that Vera Rubin will discover hundreds of new ISOs.

Slower ISOs contain less water

The lower an ISO’s relative velocity compared to the sun, the more likely it is that it will fall into the inner solar system where we can detect it; the fast ones will just speed through without necessarily being attracted much by the sun’s gravity. An ISO’s relative velocity is related to the relative velocity of its parent star, which depends significantly on whether that star hails from the thin disk with more heavy elements, or from the thick disk with fewer heavy elements.

“My results show that the velocity of an ISO correlates with its composition, and because of this we can get a handle on the types of star they may have come from,” said Hopkins.

The lower-velocity ISOs (relative to the sun) are expected to come from the thin disk, where stars and their accompanying planetary systems form from gas and dust that contain more heavy elements. The more heavy elements there are in the disk of gas and dust that forms planets and comets, the smaller the fraction of water an ISO will have.

This is because a protoplanetary disk rich in heavier elements contains a lot of carbon, and carbon (as well as iron, magnesium, silicon and sulfur) is adept at plucking up all the free oxygen atoms, two at a time, to form molecules of carbon dioxide. Water can only form from any oxygen atoms that are left over, meaning that ISOs forming within these disks generally possess a lower fraction of water.

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Could this lack of water explain why ‘Oumuamua did not display a cometary tail?

“Because it had a lower velocity relative to the sun, it probably did come from a thin disk star with more heavy elements,” said Hopkins. However, he is keen to point out the caveat that we don’t know ‘Oumuamua’s history — it could have lost its water and other volatile elements some other way. Perhaps they were eradicated by cosmic rays while traveling through interstellar space, for example, or by too many close passes to its parent star before it was ejected.

Borisov, on the other hand, was in the middle range for water content based on spectral observations of its tail.

With currently only two examples of ISO, it is difficult to draw too many conclusions. However, once the Vera Rubin Observatory is up and running later this decade, the hundreds of ISOs that it should find will be able to provide a fuller picture of where they are coming from and what their chemical properties are.

“If there’s a bias towards ISOs moving similarly to the sun falling into the inner solar system, then we would expect to see more ISOs from the thin disk,” said Hopkins.

That might mean we’ll see more objects similar to ‘Oumuamua rather than Borisov. Only time will tell how correct that prediction is.

 

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Here’s how Helene and other storms dumped a whopping 40 trillion gallons of rain on the South

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More than 40 trillion gallons of rain drenched the Southeast United States in the last week from Hurricane Helene and a run-of-the-mill rainstorm that sloshed in ahead of it — an unheard of amount of water that has stunned experts.

That’s enough to fill the Dallas Cowboys’ stadium 51,000 times, or Lake Tahoe just once. If it was concentrated just on the state of North Carolina that much water would be 3.5 feet deep (more than 1 meter). It’s enough to fill more than 60 million Olympic-size swimming pools.

“That’s an astronomical amount of precipitation,” said Ed Clark, head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama. “I have not seen something in my 25 years of working at the weather service that is this geographically large of an extent and the sheer volume of water that fell from the sky.”

The flood damage from the rain is apocalyptic, meteorologists said. More than 100 people are dead, according to officials.

Private meteorologist Ryan Maue, a former NOAA chief scientist, calculated the amount of rain, using precipitation measurements made in 2.5-mile-by-2.5 mile grids as measured by satellites and ground observations. He came up with 40 trillion gallons through Sunday for the eastern United States, with 20 trillion gallons of that hitting just Georgia, Tennessee, the Carolinas and Florida from Hurricane Helene.

Clark did the calculations independently and said the 40 trillion gallon figure (151 trillion liters) is about right and, if anything, conservative. Maue said maybe 1 to 2 trillion more gallons of rain had fallen, much if it in Virginia, since his calculations.

Clark, who spends much of his work on issues of shrinking western water supplies, said to put the amount of rain in perspective, it’s more than twice the combined amount of water stored by two key Colorado River basin reservoirs: Lake Powell and Lake Mead.

Several meteorologists said this was a combination of two, maybe three storm systems. Before Helene struck, rain had fallen heavily for days because a low pressure system had “cut off” from the jet stream — which moves weather systems along west to east — and stalled over the Southeast. That funneled plenty of warm water from the Gulf of Mexico. And a storm that fell just short of named status parked along North Carolina’s Atlantic coast, dumping as much as 20 inches of rain, said North Carolina state climatologist Kathie Dello.

Then add Helene, one of the largest storms in the last couple decades and one that held plenty of rain because it was young and moved fast before it hit the Appalachians, said University of Albany hurricane expert Kristen Corbosiero.

“It was not just a perfect storm, but it was a combination of multiple storms that that led to the enormous amount of rain,” Maue said. “That collected at high elevation, we’re talking 3,000 to 6000 feet. And when you drop trillions of gallons on a mountain, that has to go down.”

The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, Clark, Maue and Corbosiero said.

North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.

Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”

Storms are getting wetter as the climate change s, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.

Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.

For Dello, the “fingerprints of climate change” were clear.

“We’ve seen tropical storm impacts in western North Carolina. But these storms are wetter and these storms are warmer. And there would have been a time when a tropical storm would have been heading toward North Carolina and would have caused some rain and some damage, but not apocalyptic destruction. ”

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Follow AP’s climate coverage at https://apnews.com/hub/climate

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Follow Seth Borenstein on Twitter at @borenbears

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Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.

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‘Big Sam’: Paleontologists unearth giant skull of Pachyrhinosaurus in Alberta

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It’s a dinosaur that roamed Alberta’s badlands more than 70 million years ago, sporting a big, bumpy, bony head the size of a baby elephant.

On Wednesday, paleontologists near Grande Prairie pulled its 272-kilogram skull from the ground.

They call it “Big Sam.”

The adult Pachyrhinosaurus is the second plant-eating dinosaur to be unearthed from a dense bonebed belonging to a herd that died together on the edge of a valley that now sits 450 kilometres northwest of Edmonton.

It didn’t die alone.

“We have hundreds of juvenile bones in the bonebed, so we know that there are many babies and some adults among all of the big adults,” Emily Bamforth, a paleontologist with the nearby Philip J. Currie Dinosaur Museum, said in an interview on the way to the dig site.

She described the horned Pachyrhinosaurus as “the smaller, older cousin of the triceratops.”

“This species of dinosaur is endemic to the Grand Prairie area, so it’s found here and nowhere else in the world. They are … kind of about the size of an Indian elephant and a rhino,” she added.

The head alone, she said, is about the size of a baby elephant.

The discovery was a long time coming.

The bonebed was first discovered by a high school teacher out for a walk about 50 years ago. It took the teacher a decade to get anyone from southern Alberta to come to take a look.

“At the time, sort of in the ’70s and ’80s, paleontology in northern Alberta was virtually unknown,” said Bamforth.

When paleontogists eventually got to the site, Bamforth said, they learned “it’s actually one of the densest dinosaur bonebeds in North America.”

“It contains about 100 to 300 bones per square metre,” she said.

Paleontologists have been at the site sporadically ever since, combing through bones belonging to turtles, dinosaurs and lizards. Sixteen years ago, they discovered a large skull of an approximately 30-year-old Pachyrhinosaurus, which is now at the museum.

About a year ago, they found the second adult: Big Sam.

Bamforth said both dinosaurs are believed to have been the elders in the herd.

“Their distinguishing feature is that, instead of having a horn on their nose like a triceratops, they had this big, bony bump called a boss. And they have big, bony bumps over their eyes as well,” she said.

“It makes them look a little strange. It’s the one dinosaur that if you find it, it’s the only possible thing it can be.”

The genders of the two adults are unknown.

Bamforth said the extraction was difficult because Big Sam was intertwined in a cluster of about 300 other bones.

The skull was found upside down, “as if the animal was lying on its back,” but was well preserved, she said.

She said the excavation process involved putting plaster on the skull and wooden planks around if for stability. From there, it was lifted out — very carefully — with a crane, and was to be shipped on a trolley to the museum for study.

“I have extracted skulls in the past. This is probably the biggest one I’ve ever done though,” said Bamforth.

“It’s pretty exciting.”

This report by The Canadian Press was first published Sept. 25, 2024.

The Canadian Press. All rights reserved.

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The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

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TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.

Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.

Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.

The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.

The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.

It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.

Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.

Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.

Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.

Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.

Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.

The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”

The Canadian Press. All rights reserved.

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