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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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Scientists study travels of meteorite that landed in B.C. in October – Vancouver Sun

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The small meteorite broke through a woman’s ceiling in Golden, B.C., in October, landing on her pillow, next to where she had been sleeping moments earlier.

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Scientists studying a meteorite that landed next to a B.C. woman’s head last year say it was diverted to that path about 470 million years ago.

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The small meteorite broke through a woman’s ceiling in Golden in October, landing on her pillow, next to where she had been sleeping moments earlier.

Philip McCausland, a lead researcher mapping the meteorite’s journey, said Monday they know the 4.5-billion-year-old rock collided with something about 470 million years ago, breaking into fragments and changing the trajectory of some of the pieces.

McCausland, who’s an adjunct professor at Western University in London, Ont., said the meteorite is of scientific significance because it will allow scientists to study how material from the asteroid belt arrives on Earth.

“There’s 50,000 to 60,000 identified meteorites now in the world, but most have no context. We don’t know really where they came from,” he said.

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“In cases where we have known orbits, where they were observed coming in well enough that we can reconstruct what the orbit was before it hit the Earth’s atmosphere, we can actually (determine) where they came from in the asteroid belt. Golden is one of those,” he said, referring to the location of where the meteorite landed.

Researchers determined the meteorite is an L chondrite, one of the most commonly found types of meteorites to fall to Earth. Despite this, he said only about five L chondrites have known orbits.

He said the Canadian team is now working with scientists in Switzerland, the U.K., U.S. and Italy to learn more about the meteorite and its path to Golden.

“We know we’re still going to get something interesting out of this,” McCausland said. “We actually do want to get a good handle on how things get delivered from the asteroid belt, and this is a useful part of putting that together.”

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Most of the meteorite has been returned to Ruth Hamilton, the woman who had the close call, and McCausland said it’s up to her to decide what to do with it.

Whether she decides to keep, sell or donate the rock, he said there is cultural significance of the rock to Canada. If she sells it to an international buyer, she would be required to go through the exportation process, he said.

Hamilton said she hasn’t yet made up her mind on what to do with the meteor. It’s currently sitting in a safety deposit box.

“I don’t have any plans for it right now, but once they’re done analyzing it, I’ll get all the documentation that proves it’s a meteorite,” she said. “It’s going to be officially named the Golden Meteorite.”

Before her roof is permanently repaired this spring, Hamilton said she intends to remove the section where the meteorite crashed through to keep it preserved alongside the rock.

McCausland said the research will likely conclude in May, and the scientists will then publish their work in an academic journal.

“Whenever something like this happens, I like to tell people it could happen to any of us; anyone can find a meteorite. It’s unlikely one will crash through your roof, but it can happen,” McCausland said. “It’s nature and, if anything, it’s a reminder that we’re part of something bigger.”

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Researchers at UBCO determine 'smart windows' can disinfect surfaces – Kelowna News – Castanet.net

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A new study at the University of British Columbia Okanagan shines a light on how sunlight can be used to disinfect surfaces in your home or workplace.

The COVID-19 pandemic has magnified concerns over how buildings might influence the health of the people who live and work in them. There has been some attention paid to ventilation, cleaning and filtration, however, the importance of daylight has been ignored, until now.

The UBCO research shows daylight passing through smart windows results in almost complete disinfection of surfaces within 24 hours while still blocking harmful ultraviolet light.

Dr. Sepideh Pakpour, an assistant professor at UBCO’s School of Engineering tested four strains of hazardous bacteria—methicillin-resistance Staphylococcus aureus, Klebsiella pneumoniae, E. coli and Pseudomonas aeruginosa—using a mini-living lab set-up. The lab used smart windows, which tint based on outdoor light conditions, and traditional windows with blinds. Dr. Pakpour found that, compared to windows with blinds, the smart windows significantly reduce bacterial growth rate. In fact the smart windows blocked more than 99.9 per cent of UV light, but still let in short-wavelength, high-energy daylight which acts as a disinfectant. This shorter wavelength light effectively eliminated contamination on glass, plastic and fabric surfaces.

Traditional window blinds block daylight, therefore, preventing surfaces from being disinfected. Dr. Pakpour noted previous research shows 92 per cent of hospital curtains can get contaminated within a week of being cleaned.

“We know that daylight kills bacteria and fungi,” she says. “But the question is, are there ways to harness that benefit in buildings, while still protecting us from glare and UV radiation? Our findings demonstrate the benefits of smart windows for disinfection, and have implications for infectious disease transmission in laboratories, health-care facilities and the buildings in which we live and work.”

A study from the Harvard Business Review points to natural light and views being among the most sought after by potential employees. Combine that with a push for “healthy buildings” as part of the COVID-19 return to work and employers could benefit from installing smart windows.

“Our buildings need to go beyond sustainable and smart to become healthy and safe environments first and foremost,” says Dr. Rao Mulpuri, Chairman and CEO at View, the company partnering with UBC for this research. “Companies are grappling with how to bring their people back to the office in a safe way. This research provides yet another reason why increased access to natural light needs to be part of the equation.”

Studies have shown that pathogenic bacteria and fungi can survive on inanimate surfaces for prolonged periods, which can lead to disease transmission.

“With the rise of antimicrobial resistance, antibiotics are no longer a silver bullet in treating health-care-associated infections, which cause tens of thousands of deaths in the US each year,” says Dr. Tex Kissoon, Vice Chair of the Global Sepsis Alliance, UBC Children’s Hospital Endowed Chair in Acute and Critical Care for Global Child Health. “The potential for daylight to sterilize surfaces and avoid these infections altogether is promising and should be factored into health-care facility design.”

Dr. Pakpour presented her findings Wednesday at the international Healthy Buildings Conference in Amsterdam.

“Our findings demonstrate the benefits of smart windows for disinfection, and have implications for infectious disease transmission in laboratories, health care facilities and the buildings in which we live and work.”

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Asteroid Bigger Than the Tallest Building on Earth Just Flew by Safely: Here's How People Are Reacting to… – Gadgets 360

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An asteroid bigger than the tallest building on Earth safely flew by on January 19. The giant rock, named 7482 (1994 PC1), zipped past our planet, nearly 1.93 million kilometres away. That’s more than five times the distance between Earth and Moon. It has been classified as “potentially hazardous” because of its size and its regular close visits to our planet, and not because it poses any threat to us. The asteroid came closest to Earth at 3:21am IST.

Astronomers say this will remain the closest approach of the asteroid for at least the next 200 years. They added that regular close visits by this asteroid should not lead to fear among people as its trajectory has a margin of error of only 133km.

The rock was travelling at a speed of 19.56kmph, relative to Earth, when it flew by us. The considerable speed with which it was travelling should have enabled amateur astronomers to spot it. It should have appeared as a point of light in the night sky. Earth Sky has shared a video of the asteroid moving rapidly in the sky. It said the video was recorded in Puerto Rico and the asteroid was visible despite a Full Moon on January 18 (local time) since the Moon was at a good distance from the asteroid’s path. See the video below (published by kevinizooropa):

Many people shared their excitement on Twitter at being able to see the asteroid or even after simply knowing that something like this had happened.

“While we were busy surviving another day, another year, another job, an asteroid bigger than Burj Khalifa just passed by…Notice the shooting star, which steals the show. Money and jobs are the biggest distraction to our real growth and finding answers to our existence,” said a user.

Some users have also shared images of the asteroid.

Many just found an opportunity to have a little fun, now that the celestial event passed safely. Check out their reactions below:

The asteroid was discovered by Australian astronomer Robert McNaught in 1994.


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