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Scientists reveal Southern Ring Nebula’s unexpected structure: ‘We were amazed’

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The glorious, billowing Southern Ring Nebula is the cocoon of a dying star — and it has a secret. Scientists have found this nebula to exhibit a double-ring structure that evidences not one, but possibly three stars at its heart.

The Southern Ring Nebula, also designated NGC 3132, is a planetary nebula located about 2,000 light-years away in the constellation of Vela, the Sails. The name “planetary nebula” is a misnomer — such nebulas have nothing to do with planets. Instead, they are the final exhalations of dying, sun-like stars, which transform inside the nebulous chrysalis until finally blossoming into a white dwarf. A nebula is formed from the dying star’s outer envelope, which is puffed off into space following the star’s red giant phase.

The Southern Ring Nebula was imaged in December 2022 by the James Webb Space Telescope (JWST), which revealed molecular hydrogen gas forming the nebula’s “exoskeleton.” This refers to warm gas radiating with a temperature equal to about 1,000 kelvin (1,340 degrees Fahrenheit, or 726 degrees Celsius) as it gets illuminated and heated by ultraviolet light coming from the white dwarf itself. That exoskeleton, however, only represents a small fraction of the molecular gas in the nebula.

A team led by Joel Kastner of the Rochester Institute of Technology went hunting for more of the nebula’s molecular gas, specifically searching for carbon monoxide gas using the Submillimeter Array (SMA), which is a group of eight radio telescopes on an inactive volcano named Mauna Kea in Hawaii. Carbon monoxide is mixed in with hydrogen and other molecular gases inside the nebula, so observing the carbon monoxide content is actually a proxy for observing all those other molecules that are not as easy to detect. Sure enough, the SMA was able to measure both the distribution and velocities of the carbon monoxide molecules, showing which parts are moving towards us and which are moving away from us.

“JWST showed us the molecules of hydrogen and how they stack up in the sky, while the Submillimeter Array shows us the carbon monoxide that is colder that you can’t see in the JWST image,” said Kastner in a press statement.

As the Southern Ring’s name suggests, it is primarily shaped (from our point of view) as a ring. The SMA observations showed that this ring is expanding, which is to be expected as the nebula slowly grows before eventually dispersing. However, the data also allowed Kastner’s team to create a three-dimensional map of the nebula’s molecular exoskeleton. This offered up a surprise. Not only were the researchers able to show that what we see as a ring is merely a lobe in a bi-polar nebula seen end-on, but they also found a second ring perpendicular to the first.

“When we started to turn the whole nebula around in 3D, we immediately saw it was really a ring, and then we were amazed to see there was another ring,” said Kastner.

The whole bizarre arrangement paints a fascinating tail of not one, not even two, but quite possibly three stars at the heart of the nebula. Only one of these stars, the most massive of the three, will have reached the end of its life — but the stellar trio, if all three really exist, are likely either too close to one another or too faint to be separately resolved, even by the JWST.

A composite near- and mid-infrared JWST image of the Southern Ring Nebula. (Image credit: NASA/ESA/CSA/STScI/O. De Marco (Macquarie University)/J. DePasquale (STScI))

There’s growing evidence that some planetary nebulas, at least those that sport complex structures, are formed from the interference of a companion star to the central dying star. For the Southern Ring, Kastner’s team posits that a triple system formed of a close binary is orbited by a more distant, third star within an orbital radius of 60 astronomical units of the binary (one astronomical unit, AU, is the distance between Earth and the sun, and in our solar system 60 AU would be out at the far edge of the Kuiper Belt).

The two lobes of the Southern Ring have a narrow, or “pinched,” waistline, like an hourglass, which is a common feature of planetary nebulas emanating from a binary star system in which one of the stars is reaching the end of its life. The binary companion is able to corral the material shed by the dying star so that it escapes along a polar, rather than equatorial, direction, forming the two lobes. The JWST’s mid-infrared observations support this hypothesis, having found an excess of infrared light coming from the central star system, which is a classic signature of a dusty disk formed from interactions between the red giant and a close binary companion.

So, that explains the first ring. The origin of the second ring, the team says, is less certain.

Though the Southern Ring appears bi-lobed, some material must have been emitted as a roughly spherical or ellipsoidal envelope of material cast off by the red giant, a rapid mass-loss event that perhaps represented its final exhalation of material to leave behind the white dwarf. The binary star system produces a series of fast, narrow jets, but if a third star is present, then the extra star’s gravity would act on the inner binary, causing the direction of the jets to “wobble,” like a spinning top. Those precessing jets would have carved out a circular hollow in the ellipsoidal component of the nebula, thereby creating the second ring.

Kastner emphasizes that this explanation is still speculative, but the nebula’s central ionized cavity does bear the evidence of such jets in its structure.

Other ring-shaped planetary nebulas, such as the Helix Nebula (NGC 7293 in Aquarius), have also been shown to have bi-lobed structures by which we are looking “down” the end of one lobe. The discovery of the second ring in the Southern Ring Nebula — or should that now be Southern Rings, plural? — is prompting astronomers to revisit some of those other well-known ring nebulas to see if they have missed second rings in them, too.

Planetary nebulas don’t just signify stellar death. They also hold the promise of new life —  literally, in a sense.

“Where does the carbon and the oxygen and the nitrogen in the universe come from?” wonders Kastner. “We’re seeing it generated in the sun-like stars that are dying, like the star that’s just died and created the Southern Ring.”

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As an expanding planetary nebula disperses into interstellar space, it spreads those molecules across the cosmos, where they wind up in giant molecular clouds that form the next generation of stars and planets.

“A lot of that molecular gas would wind up in planetary atmospheres and atmospheres can enable life,” says Kastner. Indeed, all the elements on Earth heavier than hydrogen and helium originated inside stars and were then ejected into space when those stars died.

We are literally star-stuff, as many experts like to say.

So, when we marvel at the beauty of stellar death in nebulas such as the Southern Ring, we can also imagine it as a stellar phoenix to one day rise from the ashes and begin the cycle of star-birth and death all over again. To quote Battlestar Galactica, all this has happened before, and all of this will happen again.

The findings were published on April 2 in The Astrophysical Journal.

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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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