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Here’s the James Webb telescope’s first direct image of an exoplanet

JWST also got its first direct spectrum of an object orbiting a star in another solar system

wide image of Exoplanet HIP 65426 b with four insets showing how the planet looks in different wavelengths of light (purple, blue, yellow, and red)
Exoplanet HIP 65426 b shines in four different wavelengths in this image from the James Webb Space Telescope. Purple represents 3 micrometers, blue is 4.44 micrometers, yellow is 11.4 micrometers and red is 15.5 micrometers. The shape of the planet doesn’t look like a perfect circle because of the telescope’s optics, in particular its hexagonal mirror. NASA, ESA, CSA, A Carter/UCSC, the ERS 1386 team, and A. Pagan/STScI
This is the first picture of an exoplanet from the James Webb Space Telescope. “We’re actually measuring photons from the atmosphere of the planet itself,” says astronomer Sasha Hinkley of the University of Exeter in England. Seeing those particles of light, “to me, that’s very exciting.” The planet is about seven times the mass of Jupiter and lies more than 100 times farther from its star than Earth sits from the sun, show. It’s also young, about 10 million or 20 million years old, compared with the more than 4-billion-year-old Earth, Hinkley and colleagues report in a study submitted August 31 at arXiv.org.

Those three features — size, distance and youth — made HIP 65426 b relatively easy to see, and so a good planet to test JWST’s observing abilities. And the telescope has once again surpassed astronomers’ expectations (SN: 7/11/22).

“We’ve demonstrated really how powerful JWST is as an instrument for the direct imaging of exoplanets,” says exoplanet astronomer and coauthor Aarynn Carter of the University of California, Santa Cruz.

Astronomers have found more than 5,000 planets orbiting other stars (SN: 3/22/22). But almost all of those planets were detected indirectly, either by the planets tugging on the stars with their gravity or blocking starlight as they cross between the star and a telescope’s view.

To see a planet directly, astronomers have to block out the light from its star and let the planet’s own light shine, a tricky process. It’s been done before, but for only about 20 planets total (SN: 11/13/08; SN: 3/14/13; SN: 7/22/20).

“In every area of exoplanet discovery, nature has been very generous,” says MIT astrophysicist Sara Seager, who was not involved in the JWST discovery. “This is the one area where nature didn’t really come through.” In 2017, astronomers discovered HIP 65426 b and took a direct image of it using an instrument on the Very Large Telescope in Chile. But because that telescope is on the ground, it can’t see all the light coming from the exoplanet. Earth’s atmosphere absorbs a lot of the planet’s infrared wavelengths — exactly the wavelengths JWST excels at observing. The space telescope observed the planet on July 17 and July 30, capturing its glow in four different infrared wavelengths. “These are wavelengths of light that we’ve never ever seen exoplanets in before,” Hinkley says. “I’ve literally been waiting for this day for six years. It feels amazing.” Pictures in these wavelengths will help reveal how planets formed and what their atmospheres are made of. “Direct imaging is our future,” Seager says. “It’s amazing to see the Webb performing so well.” While the team has not yet studied the atmosphere of HIP 65426 b in detail, it did — a measurement of light in a range of wavelengths — of an object orbiting a different star. The spectrum allows a deeper look into the object’s chemistry and atmosphere, astronomer Brittany Miles of UC Santa Cruz and colleagues reported September 1 at arXiv.org.

That object is called VHS 1256 b. It’s as heavy as 20 Jupiters, so it may be more like a transition object between a planet and a star, called a brown dwarf, than a giant planet. JWST found evidence that the amounts of carbon monoxide and methane in the atmosphere of the orb are out of equilibrium. That means the atmosphere is getting mixed up, with winds or currents pulling molecules from lower depths to its top and vice versa. The telescope also saw signs of sand clouds, a common feature in brown dwarf atmospheres (SN: 7/8/22).

“This is probably a violent and turbulent atmosphere that is filled with clouds,” Hinkley says. HIP 65426 b and VHS 1256 b are unlike anything we see in our solar system. They’re more than three times the distance of Uranus from their stars, which suggests they formed in a totally different way from more familiar planets. In future work, astronomers hope to use JWST to image smaller planets that sit closer to their stars. “What we’d like to do is get down to study Earths, wouldn’t we? We’d really like to get that first image of an Earth orbiting another star,” Hinkley says. That’s probably out of JWST’s reach — Earth-sized planets are still too small see. But a Saturn? That may be something JWST could focus its sights on. 
Lisa Grossman
Lisa Grossman is the astronomy writer. She has a degree in astronomy from Cornell University and a graduate certificate in science writing from University of California, Santa Cruz. She lives near Boston.

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