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Super-Earth discovered: Data will characterize planetary atmosphere models – Phys.org

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A super-Earth is discovered which can be used to test planetary atmosphere models
Moments of the virtual journey, with overlaid astronomical data. Credit: RenderArea

During the past 25 years astronomers have discovered a wide variety of exoplanets, made of rock, ice and gas, thanks to the construction of astronomical instruments designed specifically for planet searches. Also, using a combination of different observing techniques they have been able to determine a large number of masses, sizes, and hence densities of the planets, which helps them to estimate their internal composition and raises the number of planets which have been discovered outside the Solar System.

However, to study the atmospheres of the rocky , which would made it possible to characterize fully those exoplanets which are similar to Earth, is extremely difficult with currently available instruments. For that reason, the atmospheric models for rocky planets remain untested.

So it is interesting that the astronomers in the CARMENES (Calar Alto high- Resolution search for M dwarfs with Exoearths with Near-infrared and optical échelle Spectrographs), consortium in which the Instituto de Astrofisica de Canarias (IAC) is a partner, have recently published a study, led by Trifon Trifonov, an astronomer at the Max Planck Institute for Astronomy at Heidelberg (Germany), about the discovery of a hot super-Earth in orbit around a nearby Gliese 486, only 26 light years from the Sun.

To do this the scientists used the combined techniques of transit photometry and radial velocity spectroscopy, and used, among others, observations with the instrument MuSCAT2 (Multicolour Simultaneous Camera for studying Atmospheres of Transiting exoplanets) on the 1.52m Carlos Sánchez Telescope at the Teide Observatory. The results of this study have been published in the journal Science.

This virtual journey to Gliese 486b begins with its position in the night sky. After focusing on the parent star Gliese 486b, the film depicts the measurements. Finally, we fly to the exoplanet Gliese 486b and explore its possible surface, which probably resembles Venus, with a hot and dry landscape interspersed with glowing lava flows. Credit: RenderArea

The planet they discovered, named Gliese 486b, has a mass 2.8 times that of the Earth, and is only 30% bigger. “Calculating its mean density from the measurements of its mass and radius we infer that its composition is similar to that of Venus or the Earth, which have metallic nuclei inside them,” explains Enric Pallé, an IAC researcher and a co-author of the article.

Gliese 486b orbits its on a circular path every 1.5 days, at a distance of 2.5 million kilometers. In spite of being so near to its star, the planet has probably conserved part of its original atmosphere (the star is much cooler than our Sun) so that it is a good candidate to observe in more detail with the next generation of space and ground telescopes.

The diagram provides an estimate of the interior compositions of selected exoplanets based on their masses and radii in Earth units. The red dot represents Gliese 486b, and the orange symbols represent planets around cool stars like Gliese 486. The gray dots show planets housed by hotter stars. The color curves indicate the theoretical mass radius relationships for pure water at 700 K (blue), for the mineral enstatite (orange), for Earth (green), and pure iron (red). By comparison, the diagram also highlights Venus and Earth. Credit: Trifonov et al./ MPIA Graphics Department.

For Trifonov, “the fact that this planet is so near the sun is exciting because it will be possible to study it in more detail using powerful telescopes such as the iminent James Webb Space Telescope and the ELT (Extremely Large Telescope) now being built.”

Gliese 486b takes the same length of time to spin on its axis as to orbit its host star, so that it always has the same side facing the star. Although Gliese 486 is much fainter and cooler than the Sun, the radiation is so intense that the surface of the planet heats up to at least 700K (some 430 degrees C). Because of this, the suface of Gliese 486b is probably more like the surface of Venus that that of the Earth, with a hot dry landscape, with burning rivers of lava. However, unlike Venus, Gliese 486b may have a thin atmosphere.

The graph illustrates the orbit of a transiting rocky exoplanet like Gliese 486b around its host star. During the transit, the planet eclipses the stellar disk. Simultaneously, a small portion of the starlight passes through the planet’s atmosphere. As Gliese 486b continues to orbit, parts of the illuminated hemisphere become visible as phases until the planet disappears behind the star. Credit: MPIA Graphics Department.

Calculations made with existing models of planetary atmospheres can be consistent with both hot surface and thin atmosphere scenarios because stellar irradiation tends to evaporate the atmosphere, while the planet’s gravity tends to hold it back. Determining the balance between the two contributions is difficult today.

“The discovery of Gliese 486b has been a stroke of luck. If it had been around a hundred degrees hotter all its surface would be lava, and its atmosphere would be vaporized rock,” explains José Antonio Caballero, a researcher at the Astrobiology Centre (CAB, CSIC-INTA) and co-author of the article. “On the other hand, if Gliese 486b had been around a hundred degrees cooler, it would not have been suitable for the follow-up observations.”

Artist’s impression of the atmosphere of Gliese 486b. Credit: RenderArea

Future planned observations by the CARMENES team will try to determine its orbital inclination, which makes it possible for Gliese 486b to cross the line of sight between us and the surface of the star, oculting some of its light, and producing what are known as transits.

They will also make spectroscopic measurements, using emission spectroscopy, when the areas of the hemisphere lit up by the star are visible as phases of the planet (analagous to the phases of our Moon), during the orbits of Gliese 486b, before it disappears behind the star. The spectrum observed will contain information about the conditions on the illuminated hot surface of the planet.

“We can’t wait until the new telescopes are available,” admits Trifonov. “The results we may obtain with them will help us to get a better understanding of the atmospheres of rocky planets, their extensión, their very high density, their composition, and their influence in distributing energy around the planets.

Artistic impression of the surface of the newly discovered hot super-Earth Gliese 486b. With a temperature of about 700 Kelvin (430 °C), Gliese 486b possibly has an atmosphere. Credit: RenderArea

The CARMENES project, whose consortium is made up by 11 research institutions in Spain and Germany, has the aim of monitoring a set of 350 red dwarf stars to seek planets like the Earth, using a spectrograph on the 3.5 m at the Calar Alto Observatory (Spain). The present study has also used spectroscopic measurements to infer the mass of Gliese 486b. Observations were made with the MAROON-X instrument on Gemini North (8.1m) in the USA, and archive data were taken from the Keck 10 m telescope (USA) and the 3.6m telescope of ESO, (Chile).

The photometric observations come from NASA’s TESS (Transiting Exoplanet Survey Satellite) space observatory, (USA), whose data were basic for obtaining the radius of the planet, from the MuSCAT2 instrument on the 1.52m Carlos Sánchez Telescope at the Teide Observatory (Spain) and from the LCOGT (Las Cumbres Observational Global Telescope) in Chile, among others.


Explore further

Super-Earths discovered orbiting nearby red dwarf


More information:
T. Trifonov el al. A nearby transiting rocky exoplanet that is suitable for atmospheric investigation. Science (2021). science.sciencemag.org/cgi/doi … 1126/science.abd7645

Citation:
Super-Earth discovered: Data will characterize planetary atmosphere models (2021, March 4)
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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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‘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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