Latest news with #AstrophysicalJournalLetters
UPI
4 days ago
- Science
- UPI
James Webb Space Telescope discovers evidence of a new planet
Peering deep into the heart of our Milky Way galaxy, NASA's Hubble Space Telescope reveals a rich tapestry of more than half a million stars. Scientists announced Thursday evidence of a new planet. NASA via Hubble Space Telescope Aug. 7 (UPI) -- NASA's James Webb Space Telescope has discovered evidence of a giant planet orbiting a star in the solar system closest to Earth, the administration announced Thursday. The Alpha Centauri triple star system, four light-years from Earth, has long been at the center of scientists' search for life on other planets. This discovery was an important step forward in that search, they said. "While there are three confirmed plants orbiting Proxima Centauri, the presence of other worlds surrounding Alpha Centauri A and Alpha Centauri B has proved challenging to confirm," a release from NASA said. Alpha Centauri A, Alpha Centauri B and the faint red dwarf star Proxima Centauri comprise the bigger Alpha Centauri, which is visible in the far southern sky. The discovery announced Thursday provides the strongest evidence yet of a gas giant orbiting Alpha Centauri A, and has been accepted for publication by the Astrophysical Journal Letters. "If confirmed, the planet would be the closest to Earth that orbits the habitable zone of a Sun-like star," the NASA release continued. "However, because the planet candidate is a gas giant, scientists say it would not support life as we know it." The James Webb Space Telescope was designed to find the most distant galaxies in the universe, but the operations had to customize the device's "observation sequence" to search for the gas giant.
Gizmodo
4 days ago
- Science
- Gizmodo
If This Planet Is Real, It Would Break So Many Records
Exoplanet hunters have had an eye on Alpha Centauri, the closest star system to Earth at just four light-years away, for decades. We know that it consists of two Sun-like stars, Alpha Centauri A and Alpha Centauri B, as well as a faint red dwarf star, Proxima Centauri. But while researchers have previously discovered three exoplanets orbiting Proxima Centauri, the search for more worlds orbiting the system's other two stars has proven difficult. Until now: New evidence from the James Webb Space Telescope indicates there is a gas giant planet in orbit around Alpha Centauri A. And what's more, it is likely in the star's habitable zone. Researchers described this tantalizing candidate planet in two studies published today on the preprint server arXiv, with the papers forthcoming in The Astrophysical Journal Letters. If the planet is confirmed, it would break numerous records. It would be the first exoplanet ever observed around a star about the same age and temperature as our Sun, and the nearest exoplanet to Earth orbiting in the habitable zone of a Sun-like star. It would also be the closest planet to its host star ever to be imaged directly—it is likely just two astronomical units, or twice the distance between the Sun and the Earth, from its host star—rather than observed using indirect means. 'With this system being so close to us, any exoplanets found would offer our best opportunity to collect data on planetary systems other than our own,' Charles Beichman, co-lead author of the studies and an executive director of the NASA Exoplanet Science Institute, said in a statement. 'Yet, these are incredibly challenging observations to make, even with the world's most powerful space telescope, because these stars are so bright, close, and move across the sky quickly,' he explained: The closer a planet is to its star, the harder it is to spot. Researchers began the observations in August 2024, using a device on Webb's Mid-Infrared Instrument known as a coronagraphic mask. It allows researchers to block out the glare of both Alpha Centauri A and Alpha Centauri B in observations in order to see any orbiting planets, revealing the evidence of this potential record-breaking exoplanet. If the planet really does exist and orbits in Alpha Centauri A's habitable zone—a point where liquid water can exist on a planet's surface—its mid-infrared brightness indicates it's a gas giant of about the same mass of Saturn. That unfortunately means we would not expect to find any signs of life, at least as we know it. In fact it is very unlikely any world orbiting Alpha Centuari A could sustain liquid water in this zone, the researchers write, because 'the elliptical orbit of the candidate giant planet sweeps through most of Alpha Centauri A's habitable zone, making it unlikely that smaller rocky planets could survive.' That's a bummer, because rocky exoplanets within habitable zones are the focus of the search for extraterrestrial life. Nonetheless, the potential planet is 'the most similar in temperature and age to the giant planets in our solar system and nearest to our home, Earth,' explained Sanghi Aniket Sanghi, a graduate student at the California Institute of Technology who was also co-lead author on the studies. 'Its very existence in a system of two closely separated stars would challenge our understanding of how planets form, survive, and evolve in chaotic environments,' Sanghi added. It remains to be seen what future observations will reveal about the potential gas giant. Some—and especially fans of the James Cameron movie Avatar—may be particularly interested in learning if it has any moons, like the one on which the film's Na'vi are supposed to live.
CBC
22-07-2025
- Science
- CBC
Astronomers capture an image of a potential planet forming around star
Astronomers believe they have caught a planet in the act of forming, something that has never before been witnessed. Planets form out of the leftover gas and dust once a star has ignited, and it's believed that the forming planet or planets create a disk around the host star. While astronomers have seen this protoplanetary disk around many stars, they have never before photographed an actual planet forming within, an action that creates spiral-like structures. While earlier observations of this star didn't reveal any object that could be orbiting it, the team that made this discovery used a different instrument that looked at it in a different wavelength. The authors of the study, published Monday in the journal The Astrophysical Journal Letters, say they haven't yet confirmed that what they've captured is the formation of a planet or protoplanet. "We have only one image [in] only one wavelength," said Francesco Maio, a doctoral researcher at the University of Florence, and lead author of the study. "We have three images where we don't see this object. So we need to understand the properties of these candidate protoplanets." The object is roughly 440 light years away in a binary, or double, star system, and is believed to be twice the size of Jupiter. It orbits its host star at a distance similar to that of Neptune's distance from the sun. 'Like a cappuccino' Maio described finding the potential planet in the disk in a uniquely Italian way. "The disk is like a cappuccino. The planet is like a spoon in the cappuccino. And when you move the spoon inside the cappuccino, you start to form spirals," he said. Though scientists have previously observed the spirals, Maio says this is the first time they've been able to see what is potentially causing them. "We are not able until now to see the planet that perturbed and generated a spiral," he said. "So you already see this cappuccino with spirals, but we never see the spoons." The discovery was made using the Very Large Telescope (VLT) and its Enhanced Resolution Imager and Spectrograph (ERIS) instrument at the European Southern Observatory (ESO) in Chile. The disk itself was imaged by another team of astronomers using a different instrument called SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch), which can block out the light of a star in order to see if there are any objects around it. But the previous researchers didn't find anything orbiting the star. Still, researchers say it's promising. "This is an interesting observation. People have been seeing these spiral structures in protoplanetary disks for a long time," said Hanno Rein, an associate professor at the University of Toronto and an exoplanet researcher who was not part of the study. "What's usually missing is the object that is actually creating those spiral arms, or that is forming in those disks. And this team here seems to have found one strong candidate of an object that is at the base of one of those spiral arms that might be a planet forming." 2 stars, different environments Another interesting twist to this discovery is that there is another star in the system, whose environment is very different. The pair are collectively known as HD 135344AB. The star that this potential planet is orbiting is HD 135344B. Both stars are roughly the same age, Maio said. Yet, the other star in the system — HD 135344A — has no protoplanetary disk. "This is very interesting, scientifically speaking, because we don't know why two very similar stars evolved together as two different systems," Maio said. Earlier this month, astronomers looked at the second star with ESO's VLT and SPHERE instrument and found a planet with roughly 10 times Jupiter's mass. While that's one mystery, the question of whether or not there is a protoplanet in the disk of gas and dust from Monday's study will need further investigating, Maio said, and will likely require using other wavelengths to look.
Scientific American
27-06-2025
- Science
- Scientific American
How a Passing Star Could Oust Planets from the Solar System
There's a bit of a paradox about our galaxy: it's both jam-packed with stars and cavernously empty. The Milky Way is crowded in the sense that it holds hundreds of billions of stars, as well as sprawling clouds of gas and dust. But even so, there is a lot of elbow room: the nearest star to the sun is more than four light-years distant, separated from us by tens of trillions of kilometers. That's an immense distance and difficult to even analogize. Saying our fastest space probes would take tens of thousands of years to reach the nearest star is still such a ponderous concept that it's hard to grasp. Of course, there are more crowded spots, too. Some stellar clusters pack thousands of stars into a small volume of space, and the bustling galactic center swarms with stars. But out here in the galactic suburbs, stars are more spread out, providing one another plenty of room as they orbit through the Milky Way. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. Still, given enough time, some stars will encroach on our personal space. About 80,000 years ago a small red dwarf called Scholz's star passed the sun at a distance of just 0.85 light-year. Looking ahead, about 1.3 million years hence, the star Gliese 710 will give us a close shave by 0.17 light-year. That may seem like a long time on a human scale, but that's barely a tick of the galactic clock. The sun and its retinue of planets, asteroids and comets have been around for more than 4.5 billion years. Across that yawning stretch of time, it's a near certainty the sun has had some close encounters of the stellar kind. What sort of effect does that have on the solar system? We know that the sun is surrounded by a vast halo of trillions of icy bodies collectively called the Oort Cloud; although each individual object is far too faint to see with modern equipment, every now and again, one will drop down into the inner solar system and grace our skies as a long-period comet. Estimates of the cloud's size vary, but it could stretch more than a light-year from the sun. A star passing through that region could gravitationally poke at those ice balls, nudging hundreds or even thousands of them toward the sun, and some of them could hit an inner planet. Some researchers have even speculated that such a close pass could provoke a mass extinction event. Research published in the Astrophysical Journal Letters showed that the passage of Scholz's star was unlikely to trigger such an event; the star is too much of a lightweight and was moving too quickly to significantly jostle the Oort Cloud and rain death upon our world. Given enough time, however, other stars could indeed stir up trouble in the distant reaches of the outer solar system. Happily, we probably have thousands of millennia to prepare. But such a celestial drive-by can have other unsettling consequences as well. Many astronomers have wondered about the long-term stability of the solar system's planets, given that they interact with each other gravitationally over the eons. The early solar system was wracked with profound instabilities, but more recently such effects have been far more subtle. Oddly enough, Mercury, the innermost planet, is particularly susceptible to these. The physics behind this is complex, but in a nutshell, small changes in the orbit of Neptune—the major planet most affected by a star passing by—propagate inward. It tugs on Uranus, which tugs on Saturn, which tugs on Jupiter, and the solar system's most massive planet affects everything else. Its orbit and that of Mercury can fall into a resonance in which the orbital periods (the 'years' of both planets) are simple ratios of each other. When this happens, Mercury gets an added kick (literally, like when a child on a playground swing kicks at the right moment, pumping up their oscillations). It's been known for decades that these effects can change the ellipticity of Mercury's orbit, sometimes stretching it out into a long oval. If the orbit were to get too elongated, Mercury could fall into the sun or get close enough to Venus to get flung out of the solar system. Mars, too, could fall prey to this; like Mercury, it has a more oval-shaped orbit than that of Earth or Venus and can find its orbit changing shape radically over a sufficiently long time frame. In the past, most of those simulations assumed the solar system to be in isolation, with no other stars nearby sticking their noses in our business. But we know that's not the case, and such stellar interference must be accounted for to understand the solar system's evolution. Many simulations that do include passing stars don't usually take all the effects into complete consideration; for example, they run their models for a few tens of millions of years even though it can take billions for gradually growing instabilities to have an impact. Others have used limited modeling of stellar encounters, meaning that they haven't included the entire possible range of masses, velocities and passage distances expected from stars in the galaxy. Research published online in the planetary science journal Icarus last month attempts to address all these factors in more robust simulations of the solar system's dynamic evolution. What the authors find is that some celestial bodies are a little less stable than previously thought, given how often stars pass by the sun. Not surprisingly, Pluto is the hardest hit. (The researchers only modeled the eight major planets plus Pluto.) Previously, Pluto was thought to have a pretty stable orbit, but the new simulations show that over the course of about five billion years, there's a 4 percent chance for Pluto to be ejected from the solar system entirely. These passes also increase Mercury's odds of an unhappy end. Previous studies showed a roughly 1 percent chance of it dropping into the sun or being ejected from the solar system because of planetary dynamics in the next five billion years or so, but according to the new study, there's an additional 0.56 percent chance that these events could occur via stellar interactions. Mars, too, has a 0.3 percent chance of the fate of getting an extreme sunburn or starlessly wandering the galaxy. Earth isn't immune, either. The new research finds that our own fair world has a 0.2 percent chance of being involved in a planetary collision or ejected into interstellar space. The odds are low, certainly, but higher than I'd care for given the world-shattering stakes. At this point I think I should remind you of the timescale involved: we're talking five billion years into the future, which is roughly the same amount of time that's elapsed since the solar system was born in the first place. That's a long time, so this is not something you or I should personally worry about. Plus, we don't know of any stars that will pass terribly close to us for several million years anyway. In the shorter term, I'm more concerned about—in chronologically ascending order— global warming (at the timescale of decades), medium-sized asteroids (centuries), supervolcanoes (hundreds of millennia) and giant-sized asteroids (tens of millions of years). Remember, too, that the solar system has been around a long time and, crucially, Earth is still here. It's been batted around a bit, but life persists. Over the very long term, the universe is a dangerous place, but for now, for us—cosmically speaking, at least—we can breathe easy.
Yahoo
26-06-2025
- Science
- Yahoo
A Gigantic Megacomet Is Erupting as It Zooms through the Solar System
There's a giant ball of ice barreling through the solar system right now, and it's bigger than any we've seen before. It poses no threat to Earth, but this comet, called C/2014 UN271 (Bernardinelli-Bernstein), has enraptured astronomers ever since its discovery in 2021. The hulking object, sometimes jovially called a 'megacomet,' is 100 times bigger than most comets we see in the solar system. And now we're learning more about it than ever before as it zooms toward its closest approach to our sun in 2031. In a study published in the Astrophysical Journal Letters on June 12, Nathan Roth of American University and his colleagues report the first conclusive detection of carbon monoxide on the megacomet. That's a crucial finding because it might tell us more about the object's origins, history and likely upcoming behavior as it dives deeper into the solar system. 'We wanted to test what drives activity in this comet,' Roth says. 'It's so far from the sun and so cold that trying to explain what makes a comet 'work' at these distances is difficult.' C/2014 UN271 was first imaged by chance in observations from 2014. Seven years later, when astronomers actually spotted it in their archives, the comet was at more than 20 times the Earth-sun distance, inside the orbit of Neptune. But they also found that it is on a path that will bring it nearly to Saturn's orbit in 2031 before it heads out again. The comet's orbit is huge, extending out to about 55,000 times the Earth-sun distance—87 percent of a light-year and well out into the Oort Cloud of icy objects that surrounds our sun. [Sign up for Today in Science, a free daily newsletter] Following the comet's discovery astronomers used various telescopes, including the James Webb Space Telescope and the Hubble Space Telescope, to scrutinize it from afar. The object was initially thought to be as big as 370 kilometers (230 miles) across. Revised observations showed it to be about 140 kilometers (87 miles) wide. But that's still the biggest anyone has ever seen—most comets in the solar system are only one or two kilometers across. 'It's huge,' says Quanzhi Ye, an astronomer at the University of Maryland, who was not involved in Roth's study. 'It represents a part of the cometary spectrum that we don't understand.' Some of those observations revealed bursts of activity from the comet, which sprouted an enormous, enveloping 'coma' of expelled gas that stretches some 250,000 kilometers (155,000 miles) across (more than half the distance from the Earth to the moon). To find out the cause of this activity, Roth and his team used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to observe the comet in radio waves for about eight hours in March 2024. They found a clear trace of carbon monoxide spewing from the comet, suggesting that its sprawling coma is fueled, at least in part, by carbon monoxide ice sublimating—turning from solid to gas—as the comet approaches the sun. The carbon monoxide appears to be vented in jets from spots on the object's surface, possibly the result of the overhead sun heating a localized region and causing the ice to sublimate. 'If you were standing on the comet, and the sun was right overhead, this is the area where the sun is heating the surface the most and the jet originates from,' Roth says. What's not clear so far, however, is how fast the comet is spinning and whether the location of the jets is changing over time. 'Are there different jets being activated at different times? We don't know yet,' Roth says. As C/2014 UN271 gets closer, other ices that are often found on comets, such as methane and hydrogen sulfide ice, might start to sublimate, too, and add their own contributions to the object's activity. 'As we continue to monitor it, we'll be able to get a better idea of the chemical fingerprint that's preserved inside the comet,' Roth says. Rosita Kokotanekova, an astronomer at the Rozhen National Astronomical Observatory in Bulgaria, who was not part of Roth's research team, says the detection of carbon monoxide is useful because it is 'important to identify what prompts activity at these large distances.' Researchers have witnessed gas venting from other, much smaller comets at a similar distance, 'which was very puzzling,' she adds. 'People were trying to figure out what exactly is causing this activity [so far from the sun].' C/2014 UN271's size makes it an especially alluring target for study. The presence of carbon monoxide ice is doubly interesting: Analysis of available data about the comet revealed that it first exhibited signs of activity at more than 25 times the Earth-sun distance. But according to theoretical models, its carbon monoxide ice should have been sublimated by the sun's rays when the object was even farther out in the solar system. This discrepancy may mean the comet made a pass of the sun before, with sublimation first eating away at layers of ice on its surface and its current activity only being kickstarted at closer distances, when heat from sunlight reached ice deeper within the object. Finding a behemoth like C/2014 UN271, Kokotanekova says, could hint at the existence of a whole class of gigantic progenitor comets. Such comets might have been the first large, icy objects to coalesce in the solar system, after which they could have eventually broken apart to form smaller comets. 'It's possible that the small objects are mostly fragments, while the large ones, like UN271, have never collided with anything,' she says. That might mean there are more primordial megacomets awaiting discovery. If so, the recently completed Vera C. Rubin Observatory in Chile, which will begin a 10-year panoramic survey of the heavens later this year, could find more of them. 'It's so sensitive that it will certainly pick up comets of this size, quite probably even further away from us,' Ye says. Rubin's wide eye on the sky should also give us more information on C/2014 UN271 itself, says Meg Schwamb, an astronomer at Queen's University Belfast uninvolved with this latest finding. 'Rubin's going to watch it come in,' she says. That could help us get a better handle on its activity, in partnership with telescopes like ALMA. 'You need both of those pieces of information—if it got brighter, and whether the amount of carbon monoxide changed—to tell you what's going on,' Schwamb says. For now Comet UN271 remains a fascinating target of study, a giant comet like no other that is giving us a unique window into the dark frontiers of the outer solar system. 'This is just an incredibly exciting object,' Roth says. And, for astronomers eager to learn more about this and other mega comets, the best is yet to come.
