The James Webb Space Telescope has likely made its first direct image discovery of a planet orbiting a nearby star, astronomers say.
While not yet confirmed, the planet is thought to have a mass similar to Saturn, and is orbiting a young star named TWA 7.
If confirmed, it means Webb has made its first ever exoplanet discovery, and this is the lightest planet ever detected with this technique beyond our Solar System.
Making the discovery
Webb’s MIRI (Mid-Infrared Instrument) detected a faint infrared source in the dusty debris disk around star TWA 7.
TWA 7, also known as CE Antilae, is a young red dwarf star, just 6.4 million years old, located 34 lightyears from Earth.
Its disk is nearly face-on from Earth's perspective, meaning Webb was able to get a good look at it with its infrared instrument.
The distance between potential planet and TWA 7 is about 50 times the distance of the Earth from the Sun.
If it is a planet, astronomers say this would explain key features they're seeing in the debris disk.
In order to detect a faint planet next to a much bigger, brighter star, astronomers use an instrument called a coronagraph, which covers up the star so the smaller planet can be seen.
Here, they also used computer software to cancel out residual starlight and found a faint infrared source near TWA 7.
There is a small chance this source is a background galaxy, but the team say evidence strongly points it being a previously unknown planet.
Initial data suggest the object, referred to as TWA 7 b, could be a young, cold planet with a mass around 0.3 times that of Jupiter (100 Earth masses, or one Saturn mass).
Its temperature is likely around 47°C (120°F).
Evidence in the debris disk
Young stars like TWA 7 normally have a dusty disk of debris surrounding them: the leftover ingredients out of which the star formed.
And it's out of this material that planets often form in orbit around the star, just as was the case with our own Solar System.
The infrared source seen by Webb is located in a gap between one of three previously-known dust rings around TWA 7.
Astronomers say the object’s brightness, colour, distance from the star and position within the ring are consistent with a young, cold, Saturn-mass planet that's sculpting the debris disk as it orbits the star.
If verified, it would be the first time an exoplanet has been directly associated with sculpting a debris disk.
"Our observations reveal a strong candidate for a planet shaping the structure of the TWA 7 debris disk, and its position is exactly where we expected to find a planet of this mass," says Anne-Marie Lagrange, CNRS researcher at the Observatoire de Paris-PSL and Université Grenoble Alpes in France, lead author of the paper.
"This observatory enables us to capture images of planets with masses similar to those in the Solar System, which represents an exciting step forward in our understanding of planetary systems, including our own," says co-author Mathilde Malin of Johns Hopkins University and the Space Telescope Science Institute in Baltimore.
