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Exoplanetary System Found With 6 Worlds in Orbital Resonance – Universe Today

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200 light-years away from Earth, there’s a K-type main-sequence star named TOI (TESS Object of Interest) 178. When Adrian Leleu, an astrophysicist at the Center for Space and Habitability of the University of Bern, observed it, it appeared to have two planets orbiting it at roughly the same distance. But that turned out to be incorrect. In fact, six exoplanets orbit the smallish star.

And five of those six are locked into an unexpected orbital configuration.

Five of the planets are engaged in a rare rhythmic, dance around the star. In astronomical terms, they’re in an unusual orbital resonance, which means their orbits around their star display repeated patterns. That property makes them an intriguing object of study and one that could tell us a lot about how planets form and evolve.

“Through further observations, we realized that there were not two planets orbiting the star at roughly the same distance from it, but rather multiple planets in a very special configuration.”

Adrian Leleu, Center for Space and Habitability, University of Bern.

Adrian Leleu leads a team of researchers who studied the unusual phenomenon. They presented their findings in a paper titled “Six transiting planets and a chain of Laplace resonances in TOI-178.” The paper is published in the journal Astronomy and Astrophysics.

In the team’s initial observations, it appeared there were only two planets, as five of them move in such a way as to deceive the eye. But further observations showed that something else was happening in the system. “Through further observations, we realized that there were not two planets orbiting the star at roughly the same distance from it, but rather multiple planets in a very special configuration,” said lead author Leleu.

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In this artist’s animation, the rhythmic movement of the planets around the central star is represented through a musical harmony, created by attributing a note (in the pentatonic scale) to each of the planets in the resonance chain. This note plays when a planet completes either one full orbit or one half orbit; when planets align at these points in their orbits, they ring in resonance. Credit: ESO

TOI-178’s orbital resonance is similar to another familiar orbital resonance right here in our own Solar System. That one encompasses Jupiter’s moons Io, Europa, and Ganymede.

The orbital resonance shared by Ganymede, Europa, and Io is fairly simple. Io makes four full orbits for every single orbit of Ganymede and two full orbits for Europa’s full orbit. But the planets around TOI-178 have a much more complex relationship.

TOI-178’s five outer planets are in a 18:9:6:4:3 chain of resonance. The first in the chain and second from the star completes 18 orbits, the second in the chain and third from the star completes 9 orbits, and it continues on from there. The closest planet to the star isn’t part of the chain.

For a system to be orbiting its star in such an orderly and predictable fashion, conditions had to be relatively sedate in this system. Giant impacts or planet migrations would have disrupted it. “The orbits in this system are very well ordered, which tells us that this system has evolved quite gently since its birth,” explained co-author Yann Alibert from the University of Bern.

But there’s more.

In our Solar System the small inner planets are all rocky, while the planets in the outer Solar System are large and gaseous. Beyond Neptune is a region of ice dwarf planets and Kuiper Belt Objects. Image credit: NASA/JPL/IAU

In our Solar System, the inner planets are rocky, and the planets beyond the asteroid belt are not; they’re gaseous. This is one of those instances where we might be tempted to think our Solar System represents some sort of norm. But the TOI-178 system is much different. Gaseous and rocky planets are not delineated like in our system.

“It appears there is a planet as dense as the Earth right next to a very fluffy planet with half the density of Neptune, followed by a planet with the density of Neptune. It is not what we are used to,” said Nathan Hara from the Université de Genève, Switzerland, one of the researchers involved in the study. 

“This contrast between the rhythmic harmony of the orbital motion and the disorderly densities certainly challenges our understanding of the formation and evolution of planetary systems,” says Leleu.

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The team used some of the European Observatory’s most advanced, flagship instruments in this work. The ESPRESSO instrument on the VLT, and the NGTS and SPECULOOS instruments at the ESO’s Paranal Observatory. They also used the European Space Agency’s CHEOPS exoplanet satellite. These instruments all specialize in one way or another with the study of exoplanets, which are virtually impossible to detect with a “regular” telescope.

Exoplanets are a long way away from Earth, and the overpowering light from their stars makes them nearly invisible in a regular optical telescope.

The instruments used in this study detect and characterize exoplanets in a couple of different ways. But it all comes down to detecting light. The transiting method used by the NGTS (Next-Generation Transit Survey), CHEOPS (Characterizing ExOPlanet Satellite), and SPECULOOS (Search for habitable Planets EClipsing ULtra-cOOl Stars) detect the dip in starlight when an exoplanet passes in front of its star. The radial velocity method employed by ESPRESSO detects shifts in the starlight’s normal spectrum when an exoplanet tugs on the star and shifts its position ever so slightly.

By using multiple instruments with different methods and capabilities, the team was able to characterize the system in detail. The innermost planet in the system, which is not in resonance with the others, moves the fastest. It completes an orbit in just two Earth days. The slowest planet moves ten times slower than that. The planet sizes range from one to three Earth sizes, and the masses range from 1.5 to thirty times Earth’s mass.

The orbital resonance of the planets is in an exquisite balance. The authors write that “The orbital configuration of TOI-178 is too fragile to survive giant impacts, or even significant close encounters… a sudden change in period of one of the planets of less than a few .01 d can render the system chaotic.” They also write that their data “…shows that modifying a single period axis can break the resonant structure of the entire chain.”

This discovery just means more work for astronomers. The unusual orbital resonance and positions of the planets means they need to rethink some of our theories around the formation and evolution of planets and solar systems.

This figure from the study compares the density, mass, and equilibrium temperature of the TOI-178 planets with other exoplanet systems. In Kepler-60,
Kepler-80, and Kepler-223, the density of the planets decreases
when the equilibrium temperature decreases. Contrary to the three Kepler systems, in
the TOI-178 system, the density of the planets is not a growing
function of the equilibrium temperature. The team behind this study says that if they can understand why the TOI-178 system is different, it could become a sort of Rosetta Stone for deciphering solar system and planetary development. Image Credit: Leleu et al, 2021.
This figure from the study compares the density, mass, and equilibrium temperature of the TOI-178 planets with other exoplanet systems. In Kepler-60,
Kepler-80, and Kepler-223, the density of the planets decreases
when the equilibrium temperature decreases. Contrary to the three Kepler systems, in the TOI-178 system, the density of the planets is not a growing
function of the equilibrium temperature. The team behind this study says that if they can understand why the TOI-178 system is different, it could become a sort of Rosetta Stone for deciphering solar system and planetary development. Image Credit: Leleu et al, 2021.

As the authors write in their paper: “Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present.”

The nebular hypothesis, also called the Solar Nebular Disk Model (SNDM), is the working theory for the formation of our Solar System and others. According to the model, a giant molecular cloud undergoes gravitational collapse, and when enough gas gathers together, it eventually begins fusion, and a star’s life begins. Most of the material in the cloud will be taken up by the star, and in our Solar System, the Sun has the lion’s share: about 99.86%.

The remaining material makes up the protoplanetary disk, which rotates around the star in a flattened pancake shape. As material clumps together in the rotating protoplanetary disk, it eventually forms planets. There are some problems with the nebular hypothesis, and other theories have tried to explain them.

These are images of nearby protoplanetary disks. At the center of each one is a young star, and the gaps are in the disks are caused by forming exoplanets. Credit: ALMA (ESO/NAOJ/NRAO), S. Andrews et al.; NRAO/AUI/NSF, S. Dagnello
These are images of nearby protoplanetary disks. At the center of each one is a young star, and the gaps are in the disks are caused by forming exoplanets. Credit: ALMA (ESO/NAOJ/NRAO), S. Andrews et al.; NRAO/AUI/NSF, S. Dagnello

But this system challenges that theory. The SNDM suggests that rocky, terrestrial planets form nearer the star. They start out as planetary embryos and through violent mergers create planets like Venus, Mercury, Mars, and Earth. Gas giants, according to the SNDM, form out beyond the Solar System’s frost line, where planet embryos form out of frozen volatiles.

But the TOI-178 system challenges that understanding. If the planets in that system followed the SNDM, then the gas planets would be further from the star, and the rocky planets would be closer. Since they’re not, something must have disrupted them. But if something disrupted them, their orbits wouldn’t be choreographed in such an exquisite rhythm. It’s a conundrum.

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“Understanding, in a single framework, the apparent disorder in terms of planetary density on one side and the high level of order seen in the orbital architecture on the other side will be a challenge for planetary system formation models,” they write.

Systems like this are challenging to understand, but ultimately, they drive researchers to think harder and to observe more fully.

As the team of scientists write in their conclusion: “The TOI-178 system, as revealed by the recent observations described in this paper, contains a number of very important features: Laplace resonances, variation in densities from planet to planet, and a stellar brightness that allows a number of followup observations (photometric, atmospheric, and spectroscopic). It is therefore likely to become one of the Rosetta Stones for understanding planet formation and evolution, even more so if additional planets continuing the chain of Laplace resonances is discovered orbiting inside the habitable zone.”

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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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‘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.”

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