Latest news with #AstrophysicalJournalLetters
Japan Times
28-04-2025
- Science
- Japan Times
In a galaxy far, far away ... did we find life?
In the last few years, astronomers have discovered that our galaxy is teeming with planets unlike anything in our solar system. One such exotic world, K2-18b, made the news recently over what some scientists claim is tentative evidence of what could be signs of life. Others say it's far too soon to tell. K2-18b weighs in at more than eight times the mass of Earth, orbits a red dwarf star every 33 days and just might be covered with a massive ocean and blanketed by an atmosphere complete with water vapor and rain clouds, according to work done by two teams of researchers. Researchers now say they've detected hints of two compounds that would make K2-18b smell like the sea. Dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) are produced on Earth by phytoplankton and other marine microorganisms. The evidence isn't strong enough to declare alien life — yet — but with more observations, it might be. Scientists do agree on the astonishing fact that it's possible to use tiny changes in light reaching us to measure what's in the atmospheres of planets orbiting stars trillions of miles away. Previous observations of K2-18b with the Hubble Space Telescope detected carbon dioxide, methane and water vapor in its atmosphere. The newer findings, published in the Astrophysical Journal Letters, were done using the James Webb Space Telescope and strengthened the case for the sea-scented sulfur compounds. With a mass and size in between that of Earth and Neptune, it's called a sub-Neptune and fits into a size range that's not found in our solar system. The red dwarf it orbits is much dimmer than our sun but is closer, so it's warm enough for water to remain liquid. Models show it might be covered in an ocean 600 miles deep, more than 100 times the depth of our oceans. However, scientists say they can't rule out that K2-18b is a molten hellscape or a gaseous planet with no surface. The possible detection of DMS and DMDS is exciting because they constitute a biosignature — a chemical unlikely to have formed without life. Abundant oxygen here on Earth would be a similar giveaway to life-seeking alien astronomers since we acquired our oxygen-rich atmosphere only after the evolution of photosynthesis. Back in 1999, Sarah Seager, an astrophysicist at MIT, proposed a way to search for life by looking for such biosignature compounds in the atmospheres of planets around other stars — even though most such planets are invisible even to the most powerful telescopes and have to be detected indirectly by changes in stellar brightness or motion. Seager's idea would only work in cases where a planet's orbit takes it between us and its parent star, causing a slight periodic dip in starlight, like a mini eclipse. In such cases, the planet's atmosphere would alter the starlight that passes through, like a flashlight passing through fog, Seager told me. She proposed back then that scientists could observe changes in the spectrum of starlight to infer which atmospheric gases were present. Since then, Seager said, astronomers have been surprised to find hundreds of these mid-sized sub-Neptunes. "We have no solar system counterparts,' she said, "yet it appears to be the most common planet in our galaxy.' And while studying distant planets isn't the primary purpose of the James Webb telescope, it's given astronomers a new window into their compositions and potential habitability. "It's just absolutely gratifying to see the telescope being used to study untold numbers of exoplanet atmospheres ... atmospheres of all kinds that we never anticipated existing,' she said. One of her graduate students, now at Cambridge University, led this new work on K2-18b. She said they still need stronger evidence that they really detected the dimethyl sulfide and dimethyl disulfide, and then they need to show that these gases couldn't be produced by some nonbiological process. Meanwhile, other lines of evidence suggest life is abundant in the universe. Microfossils show that Earth was inhabited soon after it cooled enough to form a solid crust and the building blocks of life have been detected far from Earth. A recent NASA mission to sample an asteroid named Bennu showed it held amino acids, which make up proteins and nucleotides — the same building blocks humans use to make RNA and DNA. Detecting ET probably won't come as a single discovery credited to one group, said astrophysicist Adam Frank of the University of Rochester. Frank compares life detection to the understanding that the universe is expanding. That wasn't a scientific consensus until it was confirmed with multiple independent lines of evidence over the course of the 20th century. He said it's possible to detect not only biosignatures on distant worlds but also "techno-signatures,' including gases unlikely to be produced except through alien technology. That might include chlorofluorocarbons, which started to build up in our atmosphere after we created them to use as refrigerants, propellants for aerosol sprays and other applications. It may take a space telescope more powerful than the James Webb to determine which planets host life. That's why NASA is planning to launch a dedicated instrument called the Habitable Worlds Observatory. Given NASA's budget cuts, the future of this project is unknown, but it would be a shame to give up the search now when we're so close and the universe has produced so many weird and wonderful planets. F.D. Flam is a Bloomberg Opinion columnist covering science. She is host of the "Follow the Science' podcast.
Economic Times
28-04-2025
- Science
- Economic Times
New hope of extraterrestrial life? Scientists cautious about celebrating early, want recheck
Are we alone in this universe? A study led by the University of Cambridge provides a flicker of hope that it may not be so, and the answer may lie 120 light-years from Earth. The study, published in the Astrophysical Journal Letters last week, found hints of life in the distant planet named K2-18b. But astrophysicists are sceptical and say the study's results and the methodology need to be cross-checked by other researchers. According to the research, fingerprints of dimethyl sulphide and dimethyl disulphide molecules have been detected on the exoplanet's atmosphere. On Earth, these molecules are known to be produced by marine organisms. Interestingly, the most common hypothesis is that life on Earth originated in the ocean. The study provides evidence of 'three-sigma' significance -- a 99.7 per cent confidence that the results are not fortuitous -- about the strongest-yet of signs of life outside the Solar System, asserts the research team led by Nikku Madhusudhan, a professor of astrophysics and exoplanetary science. In an interview with PTI Videos last week, he said that given scope of the study's implications, his team was looking to increase the robustness of the results in future researches. Jayesh Goyal, a reader at the School of Earth and Planetary Sciences at the National Institute of Science Education and Research (NISER), Bhubaneswar, feels that the findings of the study are a big step forward and "pushes the limits of our understanding of exoplanet atmospheres and their habitability". "The observations on K2-18b's atmosphere highlight the extent to which this class of sub-Neptune or super-earth exoplanets could be characterised as these targets are extremely challenging to study," he told PTI. The exoplanet is 8.6 times massive than Earth, but smaller and less massive than Neptune. Hence it has been classified as a 'sub-Neptune' exoplanet. Scientists who study exoplanets contest the interpretation of the observations, saying the results are not statistically sound, given the immensity of claims of detecting biological activity outside the Solar System. "It is not a 'detection' according to the usual standards of exoplanet science," Ryan MacDonald, NASA Sagan Fellow at the University of Michigan in the US, told PTI. Data recorded by the James Webb Space Telescope's MIRI instrument was analysed for the study. The infrared facility looked at starlight transmitted through the exoplanet's atmosphere. "The study assumes that half of the new data from the Webb telescope can only be explained by dimethyl sulphide and dimethyl disulphide, neglecting other possible gases, thereby attaching a much higher statistical significance to the claims than the data supports," the astronomer said. Asa Stahl, an astrophysicist whose PhD at the US' Rice University focused on exoplanets, said the study made use of a "hugely powerful tool" for peering into a faraway planet's atmosphere. "It's an immensely difficult task -- trying to piece together what a planet over a hundred light years away is like from how starlight filters through its atmosphere." However, it is also a relatively new method, and astronomers are still figuring out the best practices for this sort of thing, added Stahl, engaged in science communication projects. Madhusudhan, while asserting that the team of researchers would look into fortifying the robustness of the study's results, also said, "When you have big breakthroughs and big paradigm shifts, you want to be really sure because it changes the very fabric of science and society in fundamental ways." "So then, the measure of robustness there is that we want to be sure to a level that there is less than one part in a million chance of a fluke, which is a very, very, very small chance of a statistical fluke or a 'just by chance'. We want to be that robust," he added. However, the currently claimed 'three-sigma' significance -- or a 0.3 per cent of being wrong -- would need to be tested, astrophysicists said. "Using the statistics in the study, the actual probability of the molecules not being present (in K2-18b's atmosphere) is about 28 per cent. Therefore, the announcement projects (a) near-absolute confidence in a result that has a good chance of not being real," MacDonald said. And same is the case with Stahl. "We won't know for sure how robust the finding is until other researchers test it." Astrophysicist Stephen Schmidt, a graduate research fellow at the Johns Hopkins University, US, re-analysed results from a 2023 study, in which Madhusudhan's team, using the James Webb space telescope, found abundant levels of carbon-containing gases -- methane and carbon dioxide -- and potential signs of dimethyl sulphide. Despite replicating the models used in the 2023 study, the results of the re-analysis (currently in a pre-print paper stage) differed from the original. Schmidt's team could not put limits on detectable amounts of carbon dioxide in K2-18b's atmosphere. The result indicated "a lot more methane compared to carbon dioxide" and therefore, "very difficult and unlikely for the exoplanet to have a habitable liquid water surface ocean, and also a biosphere or life", he explained. Schmidt said that while the University of Cambdrige-led study pushes the limits and tests the capabilities of the Webb telescope, which he stresses is important, "this can result in potentially exciting findings that aren't substantiated after further observations." Further, there are questions that need answers, to know for sure what is happening. One of these involves understanding the processes through which dimethyl sulphide and dimethyl sulphide molecules -- considered as predictors of life on exoplanets -- can form. Even as Madhusudhan's team is looking to address this aspect in future research, answers to the origins of the molecules could prove to be especially important as studies have found dimethyl sulphide on a comet and in the space between stars -- both 'lifeless' environments. Goyal said more observations of K2-18b using the Webb telescope, along with a detailed study of laboratory spectra of dimethyl sulphide and dimethyl disulphide, could help tighten or dispute the study's results. Further, a model's ability to detect chemicals accurately should be quoted in a paper, after "considering a wide variety of different molecules, rather than just those one assumes are there," MacDonald said. The astrophysicists said not one chemical or molecule, but a combination of chemicals or gases, produced in significant amounts, along with a deep understanding of the exoplanet's environment, would be needed before being confident of habitability. However, the methods used in the Cambridge-led study could hold promise in these pursuits. Stahl said, "If we ever discover life in another world, this method could be how we find out."
Malay Mail
23-04-2025
- Science
- Malay Mail
Planet on the edge: Disintegrating world with dusty tail offers rare glimpse into exoplanet death spiral
WASHINGTON, April 24 — Astronomers have spotted a small rocky planet that orbits perilously close to its host star disintegrating as its surface is vaporised by stellar heat, trailed by a comet-like tail of mineral dust up to about 9 million km long. About 5,800 planets beyond our solar system, called exoplanets, have been discovered since the 1990s. Of those, only four have been observed disintegrating in orbit, as this one is. This planet is the closest to our solar system of the four, giving scientists a unique opportunity to learn about what happens to these doomed worlds. The researchers observed the planet, named BD+05 4868 Ab, as it gradually crumbles into dust, shedding material roughly equal to the mass of Mount Everest with each orbit of its star. The tail of dust trailing the planet wraps halfway around the star. The planet is estimated as between the size of our solar system's smallest and innermost planet Mercury and Earth's moon. It is located about 140 light years away from Earth in the constellation Pegasus. A light-year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km). Its host star, a type called an orange dwarf, is smaller, cooler and dimmer than the sun, with about 70 per cent of the sun's mass and diameter and about 20 per cent of its luminosity. The planet orbits this star every 30.5 hours at a distance about 20 times closer than Mercury is to the sun. The planet's surface temperature is estimated at close to about 1,600°Celsius thanks to its close proximity to its star. As a result, the planet's surface has probably been turned to magma — molten rock. 'We expect the planet to disintegrate into dust within the next million years or so,' said Marc Hon, a postdoctoral researcher at the Massachusetts Institute of Technology's Kavli Institute for Astrophysics and Space Research and lead author of the study published on Tuesday in the Astrophysical Journal Letters. 'This is catastrophically quick in cosmic timescales. The disintegration is a runaway process. As more material from the planet turns into dust, the disintegration process gets faster,' Hon said. Once in space, the vaporised material cools down to form mineral dust that streams away from the planet. 'We know the dust grains in the tail can have sizes between large soot particles and fine grains of sand,' Hon said. 'We don't know the mineral composition of the tail yet.' The researchers detected BD+05 4868 Ab using the 'transit method,' observing a dip in the host star's brightness when the planet passes in front of it, from the perspective of a viewer on Earth. It was found using Nasa's Transiting Exoplanet Survey Satellite, or TESS, space telescope. How the planet came to have its current close-in orbit is unclear. 'The planet's orbit is not seen to be visibly decaying from the data. It is possible that the planet initially formed farther away, and had its original orbit altered under the influence of an external body, such that the planet was sent much closer to the star,' Hon said. This could have resulted from the gravitational influence of another planet or some other celestial object. The researchers plan further observations in the coming months using Nasa's James Webb Space Telescope to study the composition of the material in the tail, which could give clues about the makeup of rocky exoplanets. The search for life in other solar systems focuses on rocky exoplanets orbiting stars in the 'habitable zone,' a distance where liquid water, a key ingredient for life, can exist on a planetary surface. 'The tail is expected to contain minerals evaporated from the surface or interior of the disintegrating planet. So, this could be the crust, mantle or even the planet's core. Learning about the interiors of planets is extremely challenging. Doing this even for planets within our solar system is difficult. But BD+05 4868 Ab will allow us to directly measure the mineral composition of a terrestrial planet outside our solar system,' Hon said. 'This is definitely an exceptional opportunity for exoplanet geology and to understand the diversity and potential habitability of rocky worlds beyond our solar system,' Hon said. — Reuters
Business Recorder
23-04-2025
- Science
- Business Recorder
Planet with comet-like tail observed disintegrating near its star
WASHINGTON: Astronomers have spotted a small rocky planet that orbits perilously close to its host star disintegrating as its surface is vaporized by stellar heat, trailed by a comet-like tail of mineral dust up to about 5.6 million miles (9 million km) long. About 5,800 planets beyond our solar system, called exoplanets, have been discovered since the 1990s. Of those, only four have been observed disintegrating in orbit, as this one is. This planet is the closest to our solar system of the four, giving scientists a unique opportunity to learn about what happens to these doomed worlds. The researchers observed the planet, named BD+05 4868 Ab, as it gradually crumbles into dust, shedding material roughly equal to the mass of Mount Everest with each orbit of its star. The tail of dust trailing the planet wraps halfway around the star. The planet is estimated as between the size of our solar system's smallest and innermost planet Mercury and Earth's moon. It is located about 140 light years away from Earth in the constellation Pegasus. A light-year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km). Its host star, a type called an orange dwarf, is smaller, cooler and dimmer than the sun, with about 70% of the sun's mass and diameter and about 20% of its luminosity. The planet orbits this star every 30.5 hours at a distance about 20 times closer than Mercury is to the sun. The planet's surface temperature is estimated at close to 3,000 degrees Fahrenheit (about 1,600 degrees Celsius) thanks to its close proximity to its star. As a result, the planet's surface has probably been turned to magma - molten rock. 'We expect the planet to disintegrate into dust within the next million years or so,' said Marc Hon, a postdoctoral researcher at the Massachusetts Institute of Technology's Kavli Institute for Astrophysics and Space Research and lead author of the study published on Tuesday in the Astrophysical Journal Letters. 'This is catastrophically quick in cosmic timescales. The disintegration is a runaway process. As more material from the planet turns into dust, the disintegration process gets faster,' Hon said. Once in space, the vaporized material cools down to form mineral dust that streams away from the planet. 'We know the dust grains in the tail can have sizes between large soot particles and fine grains of sand,' Hon said. 'We don't know the mineral composition of the tail yet.' The researchers detected BD+05 4868 Ab using the 'transit method,' observing a dip in the host star's brightness when the planet passes in front of it, from the perspective of a viewer on Earth. It was found using NASA's Transiting Exoplanet Survey Satellite, or TESS, space telescope. How the planet came to have its current close-in orbit is unclear. 'The planet's orbit is not seen to be visibly decaying from the data. It is possible that the planet initially formed farther away, and had its original orbit altered under the influence of an external body, such that the planet was sent much closer to the star,' Hon said. This could have resulted from the gravitational influence of another planet or some other celestial object. The researchers plan further observations in the coming months using NASA's James Webb Space Telescope to study the composition of the material in the tail, which could give clues about the makeup of rocky exoplanets. The search for life in other solar systems focuses on rocky exoplanets orbiting stars in the 'habitable zone,' a distance where liquid water, a key ingredient for life, can exist on a planetary surface. NASA's oldest active astronaut returns to Earth on 70th birthday 'The tail is expected to contain minerals evaporated from the surface or interior of the disintegrating planet. So, this could be the crust, mantle or even the planet's core. Learning about the interiors of planets is extremely challenging. Doing this even for planets within our solar system is difficult. But BD+05 4868 Ab will allow us to directly measure the mineral composition of a terrestrial planet outside our solar system,' Hon said. 'This is definitely an exceptional opportunity for exoplanet geology and to understand the diversity and potential habitability of rocky worlds beyond our solar system,' Hon said.
Express Tribune
23-04-2025
- Science
- Express Tribune
Planet observed disintegrating near its star
Astronomers have spotted a small rocky planet that orbits perilously close to its host star disintegrating as its surface is vaporized by stellar heat, trailed by a comet-like tail of mineral dust up to about 5.6 million miles (9 million km) long. About 5,800 planets beyond our solar system, called exoplanets, have been discovered since the 1990s. Of those, only four have been observed disintegrating in orbit, as this one is. This planet is the closest to our solar system of the four, giving scientists a unique opportunity to learn about what happens to these doomed worlds. The researchers observed the planet, named BD+05 4868 Ab, as it gradually crumbles into dust, shedding material roughly equal to the mass of Mount Everest with each orbit of its star. The tail of dust trailing the planet wraps halfway around the star. The planet is estimated as between the size of our solar system's smallest and innermost planet Mercury and Earth's moon. It is located about 140 light years away from Earth in the constellation Pegasus. A light-year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km). Its host star, a type called an orange dwarf, is smaller, cooler and dimmer than the sun, with about 70% of the sun's mass and diameter and about 20% of its luminosity. The planet orbits this star every 30.5 hours at a distance about 20 times closer than Mercury is to the sun. The planet's surface temperature is estimated at close to 3,000 degrees Fahrenheit (about 1,600 degrees Celsius) thanks to its close proximity to its star. As a result, the planet's surface has probably been turned to magma - molten rock. "We expect the planet to disintegrate into dust within the next million years or so," said Marc Hon, a postdoctoral researcher at the Massachusetts Institute of Technology's Kavli Institute for Astrophysics and Space Research and lead author of the study published on Tuesday in the Astrophysical Journal Letters. "This is catastrophically quick in cosmic timescales. The disintegration is a runaway process. As more material from the planet turns into dust, the disintegration process gets faster," Hon said. Once in space, the vaporized material cools down to form mineral dust that streams away from the planet. "We know the dust grains in the tail can have sizes between large soot particles and fine grains of sand," Hon said. "We don't know the mineral composition of the tail yet." The researchers detected BD+05 4868 Ab using the "transit method", observing a dip in the host star's brightness when the planet passes in front of it, from the perspective of a viewer on Earth. It was found using NASA's Transiting Exoplanet Survey Satellite, or TESS, space telescope. How the planet came to have its current close-in orbit is unclear. "The planet's orbit is not seen to be visibly decaying from the data. It is possible that the planet initially formed farther away, and had its original orbit altered under the influence of an external body, such that the planet was sent much closer to the star," Hon said. This could have resulted from the gravitational influence of another planet or some other celestial object.
