NASA's Webb finds cold giant planet caught in cosmic tug of war: Here's why it intrigues scientists

Economic Times

15-06-2025

NASA's James Webb Space Telescope has snapped a direct image of a frozen world with an orbit so off-track it's left astronomers puzzled. Named 14 Herculis c, this distant planet lies about 58.4 light-years away in the constellation Hercules and appears to be drifting through a celestial crime scene."This is a totally new regime of study that Webb has unlocked with its extreme sensitivity in the infrared," said William Balmer, a graduate student at Johns Hopkins University and co-lead author of the new paper.
At minus 3°C, 14 Herculis c is among the coldest exoplanets ever directly imaged. Unlike the majority of observed exoplanets—usually hot and young—this one is roughly four billion years old and frigid. It is seven times as massive as Jupiter and orbits its star at a vast distance of about 1.4 billion miles.In the JWST image, it appears as a faint orange dot. That faintness is a surprise, given its size and age.'The planet's actually significantly fainter than what we'd expect,' said Balmer. 'We don't think that this is a problem with the evolutionary models, however.'
The brightness—or rather, the lack of it—may be explained by what's happening deep within the planet's atmosphere.What's truly unusual is how this planet moves. The 14 Herculis system has two known planets that orbit their host star at sharply different angles. Instead of sweeping around their star in neat loops like our solar system, the planets cross paths in an 'X' pattern.'This is the aftermath of a more violent planetary crime scene,' Balmer said. 'It reminds us that something similar could have happened to our own solar system, and that the outcomes for small planets like Earth are often dictated by much larger forces.'
Scientists believe the skewed orbit might be the result of a third planet that once existed in the system but was violently ejected during its early evolution. The remaining two appear to be locked in a long-term gravitational tug-of-war. 'These wobbles appear to be stable over long time scales,' Balmer added. 'We're trying to understand what kinds of planet-planet scatterings could produce such an exotic configuration of orbits.'Using JWST's Near-Infrared Camera and coronagraph—tools designed to block out starlight and catch faint planetary signals—astronomers were able to detect traces of carbon dioxide and carbon monoxide in the planet's atmosphere."Added information, like the perceived brightness in direct imaging, would in theory support this estimate of the planet's temperature," said Daniella C. Bardalez Gagliuffi, co-author of the paper.
Gagliuffi explained that 14 Her c behaves more like a brown dwarf than a planet in terms of atmospheric chemistry. Normally, at such low temperatures, methane would dominate. But instead, carbon molecules created in warmer atmospheric layers appear to have been churned upward before they could convert. 'This is explained by churning in the atmosphere,' she said. 'Molecules made at warmer temperatures in the lower atmosphere are brought to the cold, upper atmosphere very quickly.'The result is a planet that appears cooler and dimmer than it actually is—wrapped in a kind of cosmic disguise.Most directly imaged exoplanets are young, bright, and close to their stars. But the strange tilt and great distance of 14 Her c made it a perfect target for Webb's advanced imaging techniques."This is great news for direct imaging," Balmer said. "We could confidently predict that JWST could resolve the outermost planet in the system."With this image, JWST has expanded the known frontier of observable planets to include cold, mature giants. The discovery is more than a milestone—it's a gateway into understanding how solar systems form, clash, and settle."We want to understand how these planets change," said Balmer, "because we want to understand how we got here."The team's findings have been accepted for publication in The Astrophysical Journal Letters and were recently presented at the 246th American Astronomical Society meeting in Anchorage, Alaska.This isn't just about a frozen gas giant orbiting far away. It's about understanding how planetary systems form, how they fight, and how they survive. Earth's place in the cosmos may have been secured not by order, but by surviving early chaos—and Webb's sharp new eye just gave us a glimpse of what that chaos looks like elsewhere.