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BEYOND LOCAL: The James Webb Space Telescope will map the atmosphere of exoplanets – Thorold News

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This article by Louis-Philippe Coulombe, Université de Montréal originally appeared on the Conversation and is published here with permission.

Exoplanets, planets that orbit stars other than the sun, are found at distances very far from Earth. For example, the closest exoplanet to us, Proxima Centauri b, is 4.2 light years away, or 265,000 times the distance between the Earth and the sun.

To the naked eye, the planets in the solar system appear as bright spots. However, using a telescope, these dots stand out from the stars and reveal structures such as Jupiter’s Great Red Spot, Saturn’s rings, or the ice caps of Mars.

Although the presence of such phenomena is expected on exoplanets, their distance from the Earth prevents us from directly resolving their surfaces. Nevertheless, there are ways to learn more about the structure of their atmospheres and map them.

I am a PhD student in astrophysics at the University of Montreal. My work is related to the characterization of exoplanet atmospheres. More specifically, my research focuses on the development of tools to map the atmosphere of exoplanets using observations from the James Webb Space Telescope.

The telescope, launched on Dec. 25, 2021, is expected to revolutionize the field of exoplanetary science.

Detecting and characterizing exoplanets

Apart from a few special cases where light from a planet can be observed directly, the majority of exoplanets are detected using indirect methods. An indirect method consists of observing the effect of the planet’s presence on the light emitted by its star.

The transit method has led to the greatest number of exoplanet detections. A transit occurs when, from our perspective, an exoplanet passes in front of its host star. During the transit, the light from the star decreases as the star’s surface is partially obscured by the planet.

Light is divided into a spectrum of wavelengths that correspond to different colours. When a transit is observed at several wavelengths, it is possible to measure the atmospheric composition of the exoplanet. For example, water molecules strongly absorb light in the infrared wavelengths, making the planet appear larger, since its atmosphere blocks a larger fraction of the light from its star. In a similar way, it is also possible to measure the temperature of the atmosphere and to detect the presence of clouds.

In addition, a transiting planet can also pass behind its star. This phenomenon, in which only the light from the star is observed, is called secondary eclipse. By observing this, it is possible to isolate the light coming only from the planet and thus obtain additional information about its atmosphere.

The transit method is more sensitive to the presence of clouds, while the secondary eclipse method provides more information about the temperature of the atmosphere.

In general, the atmosphere of an exoplanet is considered a one-dimensional object when analyzing it. That is, its composition and temperature are considered to vary only with altitude and not with its position in longitude and latitude. To take these three dimensions into account simultaneously would require complex models as well as a high degree of observational accuracy. However, solely considering altitude may produce approximations that are not valid. On Earth, for example, the temperature at the equator is much higher than at the poles.

Some exoplanets also have strong spatial variation in their atmospheres. Hot Jupiters, similar in size to Jupiter, orbit very close to their host star and can thus reach temperatures of several thousand degrees Celsius.

In addition, these planets generally revolve around themselves at the same speed as they do around their star. This means that on these planets, a day and a year are the same length. In the same way that we can only see one side of the Moon from Earth, only one side of a hot Jupiter constantly faces its star. This phenomenon can lead to a large temperature difference between the day side, which is illuminated by the star, and the night side, which is perpetually in darkness.

Mapping methods

Although it is impossible to observe the surface of an exoplanet directly, it is possible to measure the spatial variation of the atmosphere using two methods: phase curve analysis and secondary eclipse mapping.

The phase curve is the variation of light from the star-planet system during a period of revolution. Since the planet rotates on itself during its orbit, different sections of its atmosphere are successively visible to us. From this signal, it is possible to map the intensity of the light emitted by the planet in longitude. In the case of hot Jupiters, whose day side is generally hotter, the maximum of light from the planet is near the secondary eclipse. Similarly, the minimum of the curve is near the transit, since it is then the night side that is observed.

In secondary eclipse mapping, the day side of the exoplanet is resolved. As the planet moves in and out from behind its star from our point of view, sections of it are hidden, allowing us to isolate the light emitted by a given section of its atmosphere. By measuring the amount of light emitted by each individual section, it is then possible to map the day side of the atmosphere against longitude and latitude.

The arrival of the James Webb Space Telescope

To date, phase curve analysis has been applied to several planets using space telescopes, including the Hubble, Kepler and TESS space telescopes. Secondary eclipse mapping has only been applied to one exoplanet, Hot Jupiter HD189733 b, from observations with the Spitzer space telescope. However, these observations are usually made at a single wavelength, and don’t provide a complete picture of the atmospheric processes at work on these exoplanets.

With a 6.5-metre mirror, compared to the Hubble’s 2.4-metre mirror, the Webb telescope will provide unprecedentedly precise observations over a wide range of wavelengths. Four instruments, including Canada’s NIRISS (Near-infrared Imager and Slitless Spectrograph), will observe in the infrared range and characterize the atmospheres of a multitude of exoplanets.

With the Webb telescope, it will be possible to apply the mapping methods available to us to measure the three-dimensional variation of exoplanet atmospheres. These measurements will allow us to deepen our knowledge of atmospheric processes.

As technology and instruments continue to advance, it may even be possible to map an Earth-like exoplanet in the future.

Louis-Philippe Coulombe, Étudiant au doctorat en astrophysique, Université de Montréal

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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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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