TOI 1338 b is a circumbinary planet orbiting its two stars. It was discovered by TESS. Credit: NASA’s Goddard Space Flight Center/Chris Smith
In 2021, NASA’s next-generation observatory, the James Webb Space Telescope (JWST), will take to space. Once operational, this flagship mission will pick up where other space telescopes—like Hubble, Kepler and Spitzer—left off. This means that in addition to investigating some of the greatest cosmic mysteries, it will also search for potentially habitable exoplanets and attempt to characterize their atmospheres.
This is part of what sets the JWST apart from its predecessors. Between its high sensitivity and infrared imaging capabilities, it will be able to gather data on exoplanet atmospheres like never before. However, as a NASA-supported study recently showed, planets that have dense atmospheres might also have extensive cloud cover, which could complicate attempts to gather some of the most important data of all.
For years, astronomers have used transit photometry (AKA the transit method) to detect exoplanets by monitoring distant stars for dips in brightness. This method has also proven useful in determining the atmospheric composition of some planets. As these bodies pass in front of their stars, light passes through the planet’s atmosphere, the spectra of which is then analyzed to see what chemical elements are present.
So far, this method has been useful when observing massive planets (gas giants and “super-Jupiters”) that orbit their suns at great distances. However, observing smaller, rocky planets (i.e., “Earth-like” planets) that orbit closer to their suns, which would put them within the star’s habitable zone, has been beyond the capabilities of space telescopes.
For this reason, the astronomical community has been looking forward to next-generation telescopes like the JWST. By examining the spectra of light passing through a rocky planet’s atmosphere (a method known as transmission spectroscopy) scientists will be able to look for the telltale indicators of oxygen gas, carbon dioxide, methane, and other signs associated with life (AKA “biosignatures”).
As a star’s light filters through a planet’s atmosphere on its way to Earth, the atmosphere absorbs certain wavelengths depending on its composition. Credit: ESO
Another critical element for life as we know it is water, so signatures of water vapor in a planet’s atmosphere are a prime target for future surveys. But in a new study led by Thaddeus Komacek, a postdoctoral fellow with the Department of the Geophysical Sciences at the University of Chicago, it is possible that any planet with abundant surface water will also have abundant clouds (particles of condensing ice) in its atmosphere.
For the sake of this study, Komacek and his colleagues examined whether these clouds would interfere with attempts to detect water vapor in the atmospheres of terrestrial exoplanets. Due to the number of rocky exoplanets that have been discovered within the habitable zones of M-type (red dwarf) stars in recent years, like Proxima b, neighboring red dwarfs will be a major focus of future surveys.
As Komack explained to Universe Today via email, tidally locked planets that orbit red dwarf stars are well-suited to studies involving transmission spectroscopy—and for a number of a reasons:
“Transiting planets orbiting red dwarf stars are more favorable targets than those orbiting sun-like stars because the ratio of the size of the planet to the size of the star is larger. The size of the signal in transmission scales as the square of the ratio of the size of the planet to the size of the star, so there’s a significant boost in the signal going to smaller stars than Earth.
“Another reason that planets orbiting red dwarf stars are more favorable to observe is because the ‘habitable zone,” or where we expect there to be liquid water on the surface of the planet, is much closer-in to the star… Because of these closer-in orbits, habitable rocky planets orbiting red dwarf stars will transit their star much more often, which allows observers to take many repeated observations.”
Artist’s impression of a habitable exoplanet orbiting a red dwarf star. The habitability of the planets of red dwarf stars is conjectural. Credit: ESO/M. Kornmesser
With this in mind, Komacek and his team employed two models in conjunction to generate synthetic transmission spectra of tidally locked planets around M-type stars. The first was ExoCAM, developed by Dr. Eric Wolf of Colorado University’s Laboratory for Atmospheric and Space Physics (LASP), a community Earth-system model (CESM) used to simulate Earth’s climate, which has been adapted to study exoplanet atmospheres.
Using the ExoCAM model, they simulated the climate of rocky planets orbiting red dwarf stars. Second, they employed the Planetary Spectrum Generator developed by NASA’s Goddard Space Flight Center to simulate the transmission spectrum that the JWST would detect from their simulated planet. As Komacek explained it: “These ExoCAM simulations calculated the three-dimensional distributions of temperature, water vapor mixing ratio, and liquid and ice water cloud particles. We found that planets orbiting red dwarf stars are much cloudier than Earth. This is because their entire dayside has a climate similar to the tropics of Earth, and so water vapor gets easily lofted to low pressures, where it can condense and form clouds that cover much of the dayside of the planet… PSG gave results for the apparent size of the planet in transmission as a function of wavelength, along with the uncertainty. By looking at how the size of the signal changed with wavelength, we were able to determine the size of water vapor features and compare them to the uncertainty level.”
Between these two models, the team was able to simulate planets with and without cloud cover, and what the JWST would be able to detect as a result. In the case of the former, they found that water vapor in the exoplanet’s atmosphere would almost certainly be detectable. They also found that this could be done for Earth-sized exoplanets in just 10 transits or fewer.
An artist’s illustration of the James Webb Space Telescope, set to launch in March 2021. Credit: NASA/JWST
“[W]hen we included the effects of clouds, the number of transits JWST needed to observe to detect water vapor increased by a factor of 10 to 100,” said Komacek. “There is a natural limit on how many transits JWST can observe for a given planet because JWST has a set nominal mission lifetime of five years, and the transmission observation can only be taken when the planet passes between us and its host star.”
They also found that the impact of cloud cover was especially strong with slower-rotating planets around red dwarfs. Basically, planets that have orbital periods longer than about 12 days would experience more cloud formation on their daysides. “We found that for planets orbiting a star like TRAPPIST-1 (the most favorable target known), JWST would not be able to observe enough transits to detect water vapor,” said Komacek.
These results are similar to what other researchers have noted, he added. Last year, a study led by researchers at NASA Goddard showed how cloud cover would render water vapor undetectable in the atmospheres of the TRAPPIST-1 planets. Earlier this month, another NASA Goddard-supported study showed that clouds will lower the amplitude of water vapor to the point that the JWST would eliminate them as background noise.
But before we go thinking that it’s all bad news, this study does present some suggestions for overcoming these limitations. For instance, if mission time is a factor, the JWST mission can be extended so scientists will have more time to gather data. Already, NASA hopes to have the space telescope in operation for 10 years, so a mission extension is already a possibility.
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At the same time, a lowered signal-to-noise threshold for detection could allow for more signals to be picked out of the spectra (though that would mean more false positives, as well). In addition, Komacek and his colleagues note that these results apply only to features that are below the cloud deck on exoplanets: “Because water vapor is mostly trapped below the water cloud level, the strong cloud coverage on planets orbiting red dwarf stars makes it incredibly challenging to detect water features. Importantly, it is expected that JWST will still be able to constrain the presence of key atmospheric constituents like carbon dioxide and methane in only a dozen transits or so.”
Once again, these results are supported by previous research. Last year, a study from the University of Washington examined the detectability and characteristics of the TRAPPIST-1 planets and found that clouds are not likely to have a significant impact on the detectability of oxygen and ozone features—two key biosignatures that are associated with the presence of life.
So really, the JWST might only have difficulty detecting water vapor in exoplanet atmospheres, at least where dense cloud cover is concerned. The JWST should have no trouble sniffing out other biosignatures, clouds or no clouds. Great things are expected to come from Webb, NASA’s most powerful and sophisticated space telescope to date, and it will all start next year.
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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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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.
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.”
