In a landmark achievement, the James Webb Space Telescope has directly imaged its first new exoplanet. About the same mass as Saturn, it was found in a star system about 111 light-years distant. It's the lightest planet even directly imaged and could make it easier for astronomers to find Earth-like planets in other star systems.
Image of the disk around the star TWA 7 recorded using ESO’s Very Large Telescope’s SPHERE ... More
Dubbed TWA 7b, the exoplanet — defined as a planet that orbits a star other than the sun — was found in a disk of debris (which scientists call a protoplanetary disk) around a star called TWA 7. The planet is 10 times lighter than those previously captured in images.
TWA 7 is a small red dwarf star just 111 light-years from the solar system in the Southern Hemisphere constellation Antlia. It has long been known to have three rings around it that could have planets forming within them.
It's the first confirmed detection of a planet embedded in a debris disk using the Webb Telescope's Mid-Infrared Instrument, which provides far greater sensitivity than previous instruments.
It comes just a week after Webb's Near-Infrared Camera was used to directly image another cold exoplanet called 14 Herculis c. About seven times the mass of Jupiter, it was found 60 light-years from the solar system in the constellation Hercules.
TWA 7b was found using MIRI’s coronagraph instrument, which places a disk over a star to block its light, creating an artificial eclipse that enables planets to show up around it. Exoplanets are typically found using the transit method, whereby astronomers record slight dips in the brightness of a distant star caused by a planet transiting across it. It’s then possible to calculate the size of the planet, how far away it is from the star and study the starlight shining through the planet’s atmosphere. If that method relies purely on a lucky line of sight, so does the discovery of TWA 7b. The TWA 7 star system is seen pole-on, an ideal vantage point that had allowed earlier observations to reveal its three-ring debris disk. Direct imaging, especially of low-mass planets, is notoriously difficult due to the overwhelming brightness of host stars. A paper about the discovery was published in Nature today by an international team of scientists.
In this 2020 image from the Gemini South telescope in Chile, the circumstellar disk around star TWA ... More
At about a third of the mass of Jupiter — about the same as Saturn’s, or about 100 times the mass of Earth — TWA 7b is the lowest-mass exoplanet ever directly imaged. It demonstrates JWST’s power to detect much smaller and colder planets than previously possible using the MIRI instrument's coronagraph to directly image stars. Researchers believe that with continued use of advanced coronagraphs, even Earth-sized planets could one day be imaged directly. Efforts are already underway to identify the next most promising targets.
The European Space Agency last week published the first images of an artificial total solar eclipse created in Earth orbit by its Proba-3 mission. It features two satellites that fly in formation 492 feet (150 meters) apart with millimeter precision, with one using a 1.4-meter-diameter disk that occults the sun, casting a shadow on another with a telescope and a coronagraph. Creating a total solar eclipse for six hours in every 19.6-hour orbit should allow scientists to study the sun’s corona — its hotter outer atmosphere — which is only visible during a total solar eclipse.