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This is an Actual Image of a Planet-Forming Disc in a Distant Star System – Universe Today

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In 2017, astronomers used ALMA (Atacama Large Millimeter/sub-millimeter Array) to look at the star AB Aurigae. It’s a type of young star called a Herbig Ae star, and it’s less then 10 million years old. At that time, they found a dusty protoplanetary disk there, with tell-tale gaps indicating spiral arms.

Now they’ve taken another look, and found a very young planet forming there.

Young Herbig Ae stars like AB Aurigae are of great interest to astronomers. They’re so young they’re not main sequence stars yet, and they’re still surrounded by their circumstellar disk of gas and dust. And out of that gas and dust, young planets are forming.

The disk around AB Aurigae, which is over 500 light years away, has spiral arms that meet in a knot. Scientists believe that the knot is the precise point where a young planet is forming. A new study used the SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch) instrument on the Very Large Telescope (VLT) to take a closer look at AB Aurigae and the planets developing inside its disk.

The new study is titled “Possible evidence of ongoing planet formation in AB Aurigae.” Lead author of the study is Anthony Boccaletti from the Observatoire de Paris, PSL University, France. The paper is published in the journal Astronomy and Astrophysics.

“Thousands of exoplanets have been identified so far, but little is known about how they form,” said lead author Boccaletti in a press release. Observing young, still-forming planets is a big deal in astronomy right now, but it’s difficult. The circumstellar disk around the star is difficult to see into, and even our best technology is barely up to the task.

Artist’s impression of circumstellar disk of debris around a distant star. These disk are common around younger stars, and they’re difficult to see into. Credit: NASA/JPL

The SPHERE instrument was critical to this work. It’s an advanced adaptive optics system, combined with a coronoagraph. It was developed to advance the study of exoplanets, with low-resolution spectrographic and polarimetric images. It images in both optical and infrared light. SPHERE allowed the team behind this study to focus on the earliest stages of planetary formation.

“We need to observe very young systems to really capture the moment when planets form,” said Boccaletti. That twisted knot where the spiral arms of AB Aurigae’s circumstellar disk meet is as close as we’ve come to capturing that moment.

These spirals indicate the birth of a baby planet. That’s because the planet’s mass has an effect on the less dense gas and dust in the disk. Essentially, the planet kicks the material in the disk, creating a visible wave: the spirals.

“The twist of the spiral is perfectly reproduced with a planet-driven density wave model when projection effects are accounted for.”

From the Study “Possible evidence of ongoing planet formation in AB Aurigae.”

According to Emmanuel Di Folco of the Astrophysics Laboratory of Bordeaux (LAB), France, who took part in this study, the young planets create “disturbances in the disc in the form of a wave, somewhat like the wake of a boat on a lake.” And as the young planet rotates around the central star, those disturbances become spiral arms.

The images of the AB Aurigae system showing the disc around it. The image on the right is a zoomed-in version of the area indicated by a red square on the image on the left. It shows the inner region of the disc, including the very-bright-yellow ‘twist’ (circled in white) that scientists believe marks the spot where a planet is forming. This twist lies at about the same distance from the AB Aurigae star as Neptune from the Sun. The blue circle represents the size of the orbit of Neptune. The images were obtained with the SPHERE instrument on ESO’s Very Large Telescope in polarised light. Image Credit: ESO/Boccaletti et al, 2020
The images of the AB Aurigae system showing the disc around it. The image on the right is a zoomed-in version of the area indicated by a red square on the image on the left. It shows the inner region of the disc, including the very-bright-yellow ‘twist’ (circled in white) that scientists believe marks the spot where a planet is forming. This twist lies at about the same distance from the AB Aurigae star as Neptune from the Sun. The blue circle represents the size of the orbit of Neptune. The images were obtained with the SPHERE instrument on ESO’s Very Large Telescope in polarised light. Image Credit: ESO/Boccaletti et al, 2020

In their paper the authors caution us that we’re still learning what goes on inside these circumstellar veils that surround young stars. We’re still in the early days of seeing into those structures, and they aren’t certain that this twist is a planet.

“SPHERE has delivered the deepest images ever obtained for AB Aur in scattered light. Among the many structures that are yet to be understood, we identified not only the inner spiral arms, but we also resolved a feature in the form of a twist in the eastern spiral at a separation of about 30 au.”

Are they certain it’s a planet? Not exactly, but the twist feature matches modelling. “The twist of the spiral is perfectly reproduced with a planet-driven density wave model when projection effects are accounted for,” the authors write.

Initial observations of AB Aurigae made with ALMA, but without SPHERE, showed the pair of spiral arms. But ALMA alone didn’t reveal as much information. It revealed tantalizing hints, though, that planets were forming.

ALMA image of the dust ring (red) and gaseous spirals (blue) of the circumstellar disk AB Aurigae reveal gaseous spiral arms inside a wide dust gap, providing a hint of planet formation. By ALMA (ESO/NAOJ/NRAO)/Tang et al. – https://www.almaobservatory.org/en/press-release/astronomers-found-spirals-inside-a-dust-gap-of-a-young-star-forming-disk/, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=87359440

Though ALMA is a powerful tool, SPHERE is even more powerful. It can see the very faint light from dust grains, and emissions that come from the inner disk. Astronomers were able to see the details in the spirals, and the “twist” at their center.

“The twist is expected from some theoretical models of planet formation,” says co-author Anne Dutrey, also at LAB. “It corresponds to the connection of two spirals  — one winding inwards of the planet’s orbit, the other expanding outwards — which join at the planet location. They allow gas and dust from the disc to accrete onto the forming planet and make it grow.”

The disk is an elaborate structure, and astronomers observed many other structures within it. Two of them were of particular interest, marked f1 and f2 in this image. Both of these are SPHERE images, each one with a different intensity threshold. Image Credit: Boccaletti et al, 2020.
The disk is an elaborate structure, and astronomers observed many other structures within it. Two of them were of particular interest, marked f1 and f2 in this image. Both of these are SPHERE images, each one with a different intensity threshold. Image Credit: Boccaletti et al, 2020.

There’s ample theory to support the birth of planets at the twist point. “In the early stage of planet formation, hydrodynamical simulations indicate that the accretion process generates at the planet location an inner and outer spiral pattern due to Lindblad resonances induced by disk-planet interactions,” the team writes.

But the observational evidence to back it all up has been difficult to come by. This study presents some of the best observations yet that back the theory up.

In their conclusion, the authors write “…the SPHERE observations of AB Aur in scattered light combined to the ALMA data in the thermal regime provide strong evidence that we are actually witnessing ongoing planet formation revealed by its associated spiral arms.”

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But it’s not proven yet. “Further observations would be required to confirm this result and to derive better mass estimates for potential planets in this location.”

Those further observations might not be too far in the future. The ESO’s Extremely Large Telescope (ELT) should see first light in 2025. With a 39 meter mirror, the ELT will be an enormous boost to our astronomical observing power.

“We should be able to see directly and more precisely how the dynamics of the gas contributes to the formation of planets,” lead author Boccaletti concluded.

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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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