Latest news with #Eridani
Yahoo
07-04-2025
- Science
- Yahoo
Scientists used JWST instruments 'wrong' on purpose to capture direct images of exoplanets
When you buy through links on our articles, Future and its syndication partners may earn a commission. Last week, astronomers unveiled exciting new images of planets in the HR 8799 and 51 Eridani star systems — and it was all thanks to a creative use of the James Webb Space Telescope (JWST). William Balmer, a Ph.D. candidate at Johns Hopkins University and lead author of the study, spoke to about how the images were captured by the James Webb Space Telescope, and why these results represent a major leap forward in our understanding of exoplanets, how they form and the search for extraterrestrial life. "Direct imaging is critical for studying distant planets because it tells us the most information about the structure and composition of their atmospheres, independent of the light from the host star," Balmer explained. Direct imaging of distant planets poses a major challenge due to several factors. Fore one, telescopes have difficulty distinguishing the faint light from a planet from the much brighter light emitted by its host star. The star's glare can overwhelm any signals coming from the planet, making it difficult to study the world's atmosphere in detail. This also isn't helped by the fact that most exoplanets are incredibly far away from us, which further limits the ability to capture clear images of them. Here's where the James Webb Space Telescope comes in. Its advanced technology, including its large mirror and suite of specialized instruments, allows it to detect very faint emissions coming from orbiting exoplanets in the mid-infrared range of the electromagnetic spectrum — and this capability has opened a new frontier in exoplanet research. "Different gases at various pressures and temperatures in the planet's atmosphere will absorb or emit light of specific wavelengths, and we can use these chemical imprints on the light to model with increasing clarity not only what planets are made out of, but how they might have formed based on what they're made out of," said Balmer. Balmer and colleagues took this a step further by capturing innovative coronagraphic images of exoplanets in HR 8799 and 51 Eridani — and they did so by using the JWST's coronagraphs in an unconventional way. "I like to joke that for this paper we 'used the coronagraphs wrong,' but what we really did was use a very thin part of the coronagraph mask, which allowed more starlight to diffract or leak around the edges of the coronagraph," Balmer explained. Coronagraphs, first developed in 1930 to study the sun's corona, work by blocking starlight to reveal faint surrounding objects. On the JWST, they enable high-contrast imaging of exoplanets in the near- to mid-infrared range of the electromagnetic spectrum. However, if the coronagraph blocks too much light, it can obscure not just the star but also nearby planets. To address this, Balmer's team adjusted the JWST's coronagraph masks, fine-tuning how much starlight was blocked to maximize planetary visibility. "We relied on the stability of the JWST, [first] observing our targets [and then imaging] similar stars without known planets for comparison," said Balmer. By subtracting these reference images from the target images, the team effectively removed the star's light, isolating the faint signals from the planets. "Because [the JWST] is so stable, the differences between the reference and target images are smaller than the light from the planets around our targets [allowing us to detect them more clearly]," added Balmer. The study is also notable for producing the first-ever image of HR 8799 at 4.6 microns, a wavelength in the mid-infrared range. This is a significant achievement, as Earth's atmosphere absorbs much of the light at this wavelength, making ground-based observations in the range nearly impossible. "Earth's atmosphere has only a brief window of transparency at 4.6 microns," Balmer explained. "Previous ground-based observations had attempted to image the innermost HR 8799 e at these wavelengths and failed. Some ground-based telescopes have larger mirrors than JWST, but our success highlights just how crucial the JWST's stability is for these kinds of detections." But even more exciting for the team was the JWST's ability to observe at 4.3 microns — wavelengths completely blocked by Earth's atmosphere. "The most exciting wavelength we had access to with the JWST is at 4.3 microns, where none of these planets had been observed before," said Balmer. "Since the Earth's atmosphere has a lot of carbon dioxide, [it] blocks a large amount of light at this wavelength." The JWST's advantage here is that it exists beyond Earth's atmosphere, about a million miles (1.5 million kilometers) away from our planet in space. Carbon dioxide levels reveal key details about a planet's formation. In a planetary atmosphere, carbon monoxide and carbon dioxide are both present, but their balance depends on the amount of oxygen available. Because carbon dioxide contains more oxygen than carbon monoxide, a planet with high carbon dioxide levels likely has a higher abundance of "heavy" elements like carbon, oxygen, magnesium and iron. These elements come from the materials that originally formed the planet. "Since the strength of the carbon dioxide feature in the HR 8799 planets' atmospheres is so strong, we are fairly confident that they have a larger fraction of heavy elements compared to its host star, which means they had to gather those heavy elements from somewhere," said Balmer. The most likely explanation is that these planets formed through a process called core accretion — where rocky and icy cores grew large enough to capture thick atmospheres of hydrogen and other gases with their gravity. The study's observations also revealed unexpected diversity in the "colors" of the HR 8799 system's inner planets. "The differences between the HR 8799 planets are quite interesting because previously these planets have looked relatively similar in the near-infrared," said Balmer, pointing out this example. "The mid-infrared clues us into different molecules, so it might be that the different colors of the planets in our images are due to differences in vertical mixing or composition." For example, vertical mixing, which is the process of gases moving up and down a planet's atmosphere, can result in molecules ending up in places where scientists might not expect them to be. "For instance, based on the temperatures of the HR 8799 planets, they should have a lot of methane in their upper atmospheres, and so we should see large methane absorption features," said Balmer. "Instead, we see very little methane, and a lot more carbon monoxide . This is because vertical mixing has moved warm, CO-rich gas from the deeper layers of the atmosphere up into the outer layers, where it has 'out competed' the methane that should be there." A similar atmospheric process may be at play in 51 Eridani b, where the JWST's detection at 4.1 microns suggests out-of-equilibrium carbon chemistry. This planet is much fainter than expected, likely due to high levels of carbon dioxide and carbon monoxide in its upper atmosphere. "This indicates that the planet is probably metal rich, like HR 8799, but more particularly that hot, carbon monoxide and carbon dioxide rich gases from the planet's lower atmosphere are convected up into the upper atmosphere, where they absorb more outgoing light." A similar process, for context, also occurs on Earth. — James Webb Space Telescope sees four giant alien planets circling nearby star (images) — This astronomer found a sneaky extra star in James Webb Space Telescope data — James Webb Space Telescope investigates the origins of 'failed stars' in the Flame Nebula Balmer hopes future models will improve how they account for clouds and vertical mixing, allowing for better interpretation of high-precision data. Their team has been awarded 23 more hours of JWST time to study four additional planetary systems, aiming to determine whether their gas giants formed through core accretion. Understanding this process could reveal how giant planets influence the stability and habitability of smaller, unseen terrestrial worlds.
Yahoo
01-04-2025
- Science
- Yahoo
Scientists used JWST instruments 'wrong' on purpose to capture direct images of exoplanets
When you buy through links on our articles, Future and its syndication partners may earn a commission. Last week, astronomers unveiled exciting new images of planets in the HR 8799 and 51 Eridani star systems — and it was all thanks to a creative use of the James Webb Space Telescope (JWST). William Balmer, a Ph.D. candidate at Johns Hopkins University and lead author of the study, spoke to about how the images were captured by the James Webb Space Telescope, and why these results represent a major leap forward in our understanding of exoplanets, how they form and the search for extraterrestrial life. "Direct imaging is critical for studying distant planets because it tells us the most information about the structure and composition of their atmospheres, independent of the light from the host star," Balmer explained. Direct imaging of distant planets poses a major challenge due to several factors. Fore one, telescopes have difficulty distinguishing the faint light from a planet from the much brighter light emitted by its host star. The star's glare can overwhelm any signals coming from the planet, making it difficult to study the world's atmosphere in detail. This also isn't helped by the fact that most exoplanets are incredibly far away from us, which further limits the ability to capture clear images of them. Here's where the James Webb Space Telescope comes in. Its advanced technology, including its large mirror and suite of specialized instruments, allows it to detect very faint emissions coming from orbiting exoplanets in the mid-infrared range of the electromagnetic spectrum — and this capability has opened a new frontier in exoplanet research. "Different gases at various pressures and temperatures in the planet's atmosphere will absorb or emit light of specific wavelengths, and we can use these chemical imprints on the light to model with increasing clarity not only what planets are made out of, but how they might have formed based on what they're made out of," said Balmer. Balmer and colleagues took this a step further by capturing innovative coronagraphic images of exoplanets in HR 8799 and 51 Eridani — and they did so by using the JWST's coronagraphs in an unconventional way. "I like to joke that for this paper we 'used the coronagraphs wrong,' but what we really did was use a very thin part of the coronagraph mask, which allowed more starlight to diffract or leak around the edges of the coronagraph," Balmer explained. Coronagraphs, first developed in 1930 to study the sun's corona, work by blocking starlight to reveal faint surrounding objects. On the JWST, they enable high-contrast imaging of exoplanets in the near- to mid-infrared range of the electromagnetic spectrum. However, if the coronagraph blocks too much light, it can obscure not just the star but also nearby planets. To address this, Balmer's team adjusted the JWST's coronagraph masks, fine-tuning how much starlight was blocked to maximize planetary visibility. "We relied on the stability of the JWST, [first] observing our targets [and then imaging] similar stars without known planets for comparison," said Balmer. By subtracting these reference images from the target images, the team effectively removed the star's light, isolating the faint signals from the planets. "Because [the JWST] is so stable, the differences between the reference and target images are smaller than the light from the planets around our targets [allowing us to detect them more clearly]," added Balmer. The study is also notable for producing the first-ever image of HR 8799 at 4.6 microns, a wavelength in the mid-infrared range. This is a significant achievement, as Earth's atmosphere absorbs much of the light at this wavelength, making ground-based observations in the range nearly impossible. "Earth's atmosphere has only a brief window of transparency at 4.6 microns," Balmer explained. "Previous ground-based observations had attempted to image the innermost HR 8799 e at these wavelengths and failed. Some ground-based telescopes have larger mirrors than JWST, but our success highlights just how crucial the JWST's stability is for these kinds of detections." But even more exciting for the team was the JWST's ability to observe at 4.3 microns — wavelengths completely blocked by Earth's atmosphere. "The most exciting wavelength we had access to with the JWST is at 4.3 microns, where none of these planets had been observed before," said Balmer. "Since the Earth's atmosphere has a lot of carbon dioxide, [it] blocks a large amount of light at this wavelength." The JWST's advantage here is that it exists beyond Earth's atmosphere, about a million miles (1.5 million kilometers) away from our planet in space. Carbon dioxide levels reveal key details about a planet's formation. In a planetary atmosphere, carbon monoxide and carbon dioxide are both present, but their balance depends on the amount of oxygen available. Because carbon dioxide contains more oxygen than carbon monoxide, a planet with high carbon dioxide levels likely has a higher abundance of "heavy" elements like carbon, oxygen, magnesium and iron. These elements come from the materials that originally formed the planet. "Since the strength of the carbon dioxide feature in the HR 8799 planets' atmospheres is so strong, we are fairly confident that they have a larger fraction of heavy elements compared to its host star, which means they had to gather those heavy elements from somewhere," said Balmer. The most likely explanation is that these planets formed through a process called core accretion — where rocky and icy cores grew large enough to capture thick atmospheres of hydrogen and other gases with their gravity. The study's observations also revealed unexpected diversity in the "colors" of the HR 8799 system's inner planets. "The differences between the HR 8799 planets are quite interesting because previously these planets have looked relatively similar in the near-infrared," said Balmer, pointing out this example. "The mid-infrared clues us into different molecules, so it might be that the different colors of the planets in our images are due to differences in vertical mixing or composition." For example, vertical mixing, which is the process of gases moving up and down a planet's atmosphere, can result in molecules ending up in places where scientists might not expect them to be. "For instance, based on the temperatures of the HR 8799 planets, they should have a lot of methane in their upper atmospheres, and so we should see large methane absorption features," said Balmer. "Instead, we see very little methane, and a lot more carbon monoxide . This is because vertical mixing has moved warm, CO-rich gas from the deeper layers of the atmosphere up into the outer layers, where it has 'out competed' the methane that should be there." A similar atmospheric process may be at play in 51 Eridani b, where the JWST's detection at 4.1 microns suggests out-of-equilibrium carbon chemistry. This planet is much fainter than expected, likely due to high levels of carbon dioxide and carbon monoxide in its upper atmosphere. "This indicates that the planet is probably metal rich, like HR 8799, but more particularly that hot, carbon monoxide and carbon dioxide rich gases from the planet's lower atmosphere are convected up into the upper atmosphere, where they absorb more outgoing light." A similar process, for context, also occurs on Earth. — James Webb Space Telescope sees four giant alien planets circling nearby star (images) — This astronomer found a sneaky extra star in James Webb Space Telescope data — James Webb Space Telescope investigates the origins of 'failed stars' in the Flame Nebula Balmer hopes future models will improve how they account for clouds and vertical mixing, allowing for better interpretation of high-precision data. Their team has been awarded 23 more hours of JWST time to study four additional planetary systems, aiming to determine whether their gas giants formed through core accretion. Understanding this process could reveal how giant planets influence the stability and habitability of smaller, unseen terrestrial worlds.
Yahoo
15-02-2025
- Science
- Yahoo
Scientists Intrigued by Nearby Planet That Could Potentially Support Life
Astronomers have detected a relatively close exoplanet orbiting in the habitable zone of its star, where temperatures are just right to support liquid water on the surface. As detailed in a new study published in the journal Astronomy & Astrophysics, the planet, dubbed HD 20794 d, is suspected to be what's referred to as a super-Earth, possessing around six times the mass of our world. Promisingly, it orbits a star much like our own, and resides just twenty light years away. That makes it one of the closest potentially habitable worlds that astronomers know of. There's still some major questions to be answered about the planet, and it's too early to outright say if it's capable of supporting life — but habitability certainly looks possible. "For me, it was naturally a huge joy when we could confirm the planet's existence," said study coauthor Michael Cretignier, an astrophysicist at Oxford University, in a statement about the work. "It was also a relief, since the original signal was at the edge of the spectrograph's detection limit, so it was hard to be completely convinced at that time if the signal was real or not." And because it's so close, he adds, there "hope for future space missions to obtain an image of it." The presence of exoplanets in the star system was first detected in 2011, but data at the time was lacking. It wasn't until 2022 that Cretignier and his colleagues stumbled onto something more substantive: they noticed a "wobble" in the light spectrum of the host star. One way astronomers look for exoplanets is via gravitational clues. Just as a star's gravity pulls on a planet, so does the planet on the star, and that can cause the stellar body to "wobble" out of its expected position. As a result, when the star moves closer or farther away from us, its light slightly shifts in color, which astronomers can spot. Still, to confirm the detection, the team had to sift through decades of data, including imaging by the exoplanet-hunting ESPRESSO instrument on the Very Large Telescope in Chile. "We worked on data analysis for years, gradually analyzing and eliminating all possible sources of contamination," Cretignier said. The planet's star, 82 G. Eridani, is a yellow dwarf like our Sun with about 80 percent of its mass. It's older than our Sun, however, and perhaps showing its age, is also a tad fainter. That's encouraging, but as for its newly confirmed planet, a few details remain a bit dicey. HD 20794 d's orbit is elliptical, not circular like Earth's, so the distance it keeps from its star changes dramatically as it revolves. That could make conditions on the planet's surface pretty volatile, with dramatic temperature swings; at its farthest point, the planet gets chilly enough for water to freeze. In fact, there's a chance that HD 20794 d may not be a super-Earth as suspected, but instead a what's known as a mini-Neptune, or an icy world similar to the one in our solar system but lesser in mass. Nonetheless, there's little doubt in the astronomer's minds that we should be paying close attention to this intriguing celestial neighbor. "With its location in a habitable zone and relatively close proximity to Earth, this planet could play a pivotal role in future missions that will characterize the atmospheres of exoplanets to search for biosignatures indicating potential life," Cretignier said. More on astronomy: Strange Signal Coming From Dead Galaxy, Scientists Say
