The JWST’s size and sensitivity allowed it to collect more light from this planet than any previous observatory has received. (His photo looks grainier than SPHERE’s only because the JWST observes longer infrared wavelengths.) This allowed Hinkley, Biller and their team to refine the estimate of the planet’s mass, which they pinned at about seven times the mass of Jupiter, less than that Estimate SPHERE at around 10. Their findings also help establish the planet’s radius, which is 1.4 times that of Jupiter. Simple models of planetary evolution cannot easily account for the combination of properties of this world; Carter noted that the accurate new data would allow scientists to test models against each other and “deepen our understanding.”
HIP 65426 b’s surface features aren’t visible in the image, but Biller said it would appear “probably banded” like Jupiter, with belts caused by temperature and compositional variations, and could have spots in its atmosphere caused by storms or vortices are caused.
The giant planet is inhospitable to life as we know it, but it represents a class of large planets that scientists are keen to learn more about. Jupiter likely played a key role in shaping our solar system and possibly allowing life to take root on Earth. “It would be nice to know if this works in other solar systems,” Macintosh said.
Because the JWST is so much more stable than expected, scientists say it should be able to photograph smaller-than-expected exoplanets – perhaps as small as a third the mass of Jupiter. “We could image things like Neptune and Uranus that we’ve never imaged directly before,” said Emily Rickman, an astronomer at the Space Telescope Science Institute in Maryland, which operates the JWST.
Now that the JWST’s coronagraph has passed its road test, Hinkley believes astronomers will be lining up to take otherworldly photos with it. He expects to see “definitely dozens” by the end of the telescope’s life. “I hope it’s closer to hundreds.”
Peer into the distant sky
In addition to the exoplanet photo, Hinkley’s team will announce in the coming days that they have discovered a series of molecules in the atmosphere of a putative brown dwarf — sometimes known as a “failed star” — orbiting a companion star. The object is nearly 20 times heavier than Jupiter and has a mass just below the threshold where fusion could begin at its core.
Using an instrument at JWST that breaks down the frequencies of light, a process called spectroscopy, the scientists found water, methane, carbon dioxide and sodium, all of which became visible in an unprecedented level of detail. They also detected smoky silicate clouds in the candidate brown dwarf’s atmosphere, something previously suggested but never detected for such objects. “In my opinion, this is the largest spectrum ever obtained from a substellar companion,” Hinkley said. “We’ve never seen anything like it.”