First exoplanet image
Webb telescope wows with first image of an exoplanet
The James Webb Space Telescope has taken its first picture of a planet beyond the Solar System — opening a window to understanding other worlds and underscoring the telescope’s immense capabilities.
The image (shown) is of a planet called HIP 65426 b, an object similar to Jupiter, but younger and hotter, that lies 107 parsecs from Earth in the constellation Centaurus. Although it looks like a pixelated light bulb, it is the first exoplanet image ever taken at deep infrared wavelengths, which allow astronomers to study the full range of a planet’s brightness and what it is made of (the star symbol marks HIP 65426 b’s star, whose light the telescope blocked).
“It gives us wavelengths we’ve never seen planets at before,” says Beth Biller, an astronomer at the University of Edinburgh, UK, and a member of the discovery team. The image was reported in a paper on a preprint server on 31 August (A. L. Carter et al. Preprint at https://arxiv.org/abs/2208.14990; 2022); the study has not been peer reviewed.
Astronomers know of more than 5,000 exoplanets, but they have taken pictures of only around 20. Imaging exoplanets directly is difficult, because they are often lost in the glare of the star around which they orbit.
But observing them at infrared wavelengths, as Webb does, helps to boost the contrast between star and planet. “You’re in the regime where planets are brightest and stars are dimmest,” says Aarynn Carter, an astronomer at the University of California, Santa Cruz, and lead author of the preprint.
In July this year, Carter’s team used instruments on Webb to physically block the light from HIP 65426 b’s star, allowing the planet to pop into view. HIP 65426 b orbits its star at roughly twice the distance that Pluto orbits the Sun.
Unlocking the extra infrared wavelengths allowed the astronomers to better understand how much energy the planet’s atmosphere radiates. That, in turn, allowed them to use models of stellar evolution to pin down its mass to 7 times, and its radius to 1.45 times, that of Jupiter.
HIP 65426 b is probably around 14 million years old, making it “a baby Jupiter”, Biller says. Our Solar System is around 4.5 billion years old.