Latest news with #exoplanet
CTV News
3 days ago
- Science
- CTV News
A surprising study revealed biological activity on a distant planet. Weeks later, scientists say there's more to the story
An artist's concept shows what K2-18b might look like. Thought to be covered entirely in liquid water with a hydrogen-rich atmosphere, the exoplanet may be a good place to look for biological activity. A tiny sign revealed in April seemed like it might change the universe as we know it. Astronomers had detected just a hint, a glimmer of two molecules swirling in the atmosphere of a distant planet called K2-18b — molecules that on Earth are produced only by living things. It was a tantalizing prospect: the most promising evidence yet of an extraterrestrial biosignature, or traces of life linked to biological activity. But only weeks later, new findings suggest the search must continue. 'It was exciting, but it immediately raised several red flags because that claim of a potential biosignature would be historic, but also the significance or the strength of the statistical evidence seemed to be too high for the data,' said Dr. Luis Welbanks, a postdoctoral research scholar at Arizona State University's School of Earth and Space Exploration. While the molecules identified on K2-18b by the April study — dimethyl sulfide, or DMS, and dimethyl disulfide, or DMDS — are associated largely with microbial organisms on our planet, scientists point out that the compounds can also form without the presence of life. Now, three teams of astronomers not involved with the research, including Welbanks, have assessed the models and data used in the original biosignature discovery and got very different results, which they have submitted for peer review. Meanwhile, the lead author of the April study, Nikku Madhusudhan, and his colleagues have conducted additional research that they say reinforces their previous finding about the planet. And it's likely that additional observations and research from multiple groups of scientists are on the horizon. The succession of research papers revolving around K2-18b offers a glimpse of the scientific process unfolding in real time. It's a window into the complexities and nuances of how researchers search for evidence of life beyond Earth — and shows why the burden of proof is so high and difficult to reach. Noisy data Located 124 light-years from Earth, K2-18b is generally considered a worthy target to scour for signs of life. It is thought to be a Hycean world, a planet entirely covered in liquid water with a hydrogen-rich atmosphere, according to previous research led by Madhusudhan, a professor of astrophysics and exoplanetary science at the University of Cambridge's Institute of Astronomy. And as such, K2-18b has rapidly attracted attention as a potentially habitable place beyond our solar system. Convinced of K2-18b's promise, Madhusudhan and his Cambridge colleagues used observations of the planet by the largest space telescope in operation, the James Webb Space Telescope, to study the planet further. But two scientists at the University of Chicago — Dr. Rafael Luque, a postdoctoral scholar in the university's department of astronomy and astrophysics, and Michael Zhang, a 51 Pegasi b / Burbidge postdoctoral fellow — spotted some problems with what they found. After reviewing Madhusudhan and his team's April paper, which followed up on their 2023 research, Luque and Zhang noticed that the Webb data looked 'noisy,' Luque said. Noise, caused by imperfections in the telescope and the rate at which different particles of light reach the telescope, is just one challenge astronomers face when they study distant exoplanets. Noise can distort observations and introduce uncertainties into the data, Zhang said. Trying to detect specific gases in distant exoplanet atmospheres introduces even more uncertainty. The most noticeable features from a gas like dimethyl sulfide stem from a bond of hydrogen and carbon molecules — a connection that can stretch and bend and absorb light at different wavelengths, making it hard to definitively detect one kind of molecule, Zhang said. 'The problem is basically every organic molecule has a carbon-hydrogen bond,' Zhang said. 'There's hundreds of millions of those molecules, and so these features are not unique. If you have perfect data, you can probably distinguish between different molecules. But if you don't have perfect data, a lot of molecules, especially organic molecules, look very similar, especially in the near-infrared.'
The Independent
5 days ago
- Science
- The Independent
A dwarf star birthed a giant planet – but scientists don't know how
Astronomers have discovered an unusually large exoplanet orbiting the small star TOI-6894, located 240 light-years away in the constellation Leo, challenging existing planetary formation theories. The planet, a gas giant similar in size to Saturn, orbits a red dwarf star that is only about one-fifth the mass of our sun, a pairing that defies current models predicting smaller planets around such stars. This discovery marks the smallest-known star to host such a large planet, about 40 per cent smaller than previous record holders. Researchers have been left puzzled by the finding, but suggest it indicates that giant planets can form around even the smallest stars. Data from Nasa 's TESS and the European Southern Observatory 's VLT were used in the study, and there are plans to further investigate the planet's composition using the James Webb Space Telescope.
Yahoo
6 days ago
- General
- Yahoo
A Super-Tiny Star Gave Birth to a Giant Planet And We Don't Know How
A giant conundrum has been found orbiting a teeny tiny red dwarf star just a fifth of the size of the Sun. Such small stars were thought to be incapable of producing giant planets. But there, in its orbit, appears to be unmistakable evidence of an absolute unit: a gas giant around the size of Saturn. TOI-6894b, as the exoplanet is named, has 86 percent of the radius of Jupiter. At just 23 percent of the radius and 21 percent of the mass of the Sun, its parent TOI-6894 is the smallest star yet around which a giant world has been found. "I was very excited by this discovery," says astrophysicist Edward Bryant of the University of Warwick in the UK, who led the large international research team. "We did not expect planets like TOI-6894b to be able to form around stars this low-mass. This discovery will be a cornerstone for understanding the extremes of giant planet formation." Planets are born from the material that's left over from the formation processes of its host star. Stars form when a dense clump of material in a cloud of gas and dust collapses under gravity. Material from that cloud spools around the spinning protostar in a disk that feeds the star's growth; when the star is large enough to push the material away with its stellar wind, growth stops. The remaining material is what makes planets. The dust clumps together, gradually building worlds that end up orbiting the star. Here's the thing, though. The amount of material in the disk is thought to be proportional to the mass of the star. The reason tiny red dwarf stars shouldn't be able to make giant planets is because there just oughtn't be enough material to do so. Nevertheless, these strange, 'impossible' systems show up from time to time, suggesting not just that giant planets can form around tiny stars, but that the process is not all that uncommon. We don't have a good handle on just how common it is, so Bryant and his team embarked on a mission to scour TESS data for clues. "I originally searched through TESS observations of more than 91,000 low-mass red-dwarf stars looking for giant planets," he says. "Then, using observations taken with one of the world's largest telescopes, ESO's VLT, I discovered TOI-6894b, a giant planet transiting the lowest mass star known to date to host such a planet." Exoplanets are usually found via a technique known as the transit method. When an exoplanet orbiting a star passes between us, the observers, and the star, that star's light dims minutely. Astronomers can determine the presence of an exoplanet by looking for periodic dips in the star's light. It's usually a tiny signal that takes quite a bit of analysis to find. When the researchers looked at TOI-6894, they found its light dimming by an absolutely whopping 17 percent. According to the team's observations of the transits, that would make the diameter of the star about 320,000 kilometers (200,000 miles), while the exoplanet is around 120,000 kilometers across. Follow-up observations to see how much this giant exoplanet's gravity affects the orbital motion of the star revealed the mass of TOI-6894b. It's just 17 percent of the mass of Jupiter, suggesting an exoplanet atmosphere that is light and fluffy. This is exciting for a few reasons. Because the exoplanet has such deep transits, it's a perfect candidate for atmosphere study. During those transits, some of the star's light filters through the diffuse atmosphere. As it does so, it can become altered by the atoms and molecules therein, allowing scientists to literally see what TOI-6894b is made of. A team of astronomers has already applied for time with JWST to perform these atmospheric studies. Because the exoplanet is quite cool (temperature wise, but also just in general), they expect to find a lot of methane. "This system provides a new challenge for models of planet formation, and it offers a very interesting target for follow-up observations to characterize its atmosphere," says astrophysicist Andrés Jordán of the Millennium Institute of Astrophysics in Chile. Hopefully, these studies will also shed some light on how TOI-6894b formed. There are two scenarios astronomers prefer for gas giants: a gradual accumulation of material from the bottom up, or the direct collapse of an instability in the protoplanetary disk. Based on the team's observations, neither scenario quite works. More detail on the composition of TOI-6894b could help tease out which is the more likely pathway for the formation of giant worlds orbiting tiny stars. "It's an intriguing discovery. We don't really understand how a star with so little mass can form such a massive planet!" says astrophysicist Vincent Van Eylen of University College London. "This is one of the goals of the search for more exoplanets. By finding planetary systems different from our Solar System, we can test our models and better understand how our own Solar System formed." The discovery has been published in Nature Astronomy. Water Discovered Around a Young, Sun-Like Star For First Time June's Full Moon Will Be The Lowest in The Sky For Decades. Here's Why. The Milky Way Might Not Crash Into The Andromeda Galaxy After All
CNET
06-05-2025
- Science
- CNET
The James Webb Telescope Just Zoomed In On A Hot, Haze-Free Exoplanet
The James Webb Space Telescope just zoomed in on the atmosphere of a planet discovered in 2020 -- and now we have the clearest data about an exoplanet that there's ever been. The awkwardly named Planet TOI-421b's exoplanet status means that it doesn't orbit our sun. (Exoplanets are defined as any planet beyond our solar system.) Don't expect to travel there any time soon. It's 244 light-years away from the Earth -- for comparison, the dwarf planet Pluto is only five and a half light-hours from us. Even still, the planet orbits a similar star to our sun, and is considered a sub-Neptume planet, because it's larger than Earth, but smaller than Neptune, which itself is four times larger than Earth. The planet was discovered through astronomical transit, which means astronomers noticed that a star dimmed as TOI-421b passed it in orbit. This isn't a heavenly body that a hobbyist can spot, but the best cameras out there can get you started with astrophotography. The exoplanet was mapped out by a team of astronomers from NASA, the European Space Agency and the Canadian Space Agency, who worked together to analyze the planet's atmosphere using a form of study called spectroscopy. By parsing out light frequencies in a planet's atmosphere, scientists can figure out what elements are present -- and which are missing. TOI-421b's atmosphere is rich in hydrogen, and contains signs of water vapor. But it doesn't contain signs of methane, which leads to hazy, unclear atmospheric conditions. Most sub-Neptune exoplanets have atmospheres shrouded in haze, which makes them difficult to image. TOI-421b was chosen for the project because the initial analysis led scientists to believe that the planet could be accurately and clearly pictured through spectroscopic imaging. Is this planet a 'unique snowflake'? The team of astronomers published their findings in the Astrophysical Journal Letters, where all of the key data for the project is collected in one paper. You can read through the full write-up here. The spectroscopic images of TOI-421b are accessible in the results section of the paper, and they paint a picture of many of the exoplanet's strange and exciting properties. Other sub-Neptune worlds had atmospheres filled with heavy gases that indicated they were potentially mostly composed of water, but TOI-421b is composed of lightweight gases -- much like the star it orbits. This has raised questions about how different types of stars could potentially impact the atmosphere of their orbiting planets. In a statement to Mashable, Eliza Kempton, the lead investigator on the study, said it was something the astronomers would need to further explore. "We can see if this planet just turned out to be kind of a unique snowflake, or is it emblematic of a class of planets that all have similar properties," she said.
