James Webb Space Telescope discovers its first new exoplanet

James Webb Space Telescope discovers its first new exoplanet


Since its 2021 launch, the James Webb Space Telescope (JWST) has revolutionized our understanding of the early universe. Now, for the first time, Webb has made its own groundbreaking discovery: an exoplanet never before observed.

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Webb directly imaged a young gas giant planet, roughly the size of Saturn, orbiting a star smaller than our sun, about 110 light-years from Earth in the constellation Antlia. This finding is particularly significant because most of the nearly 5,900 exoplanets discovered have been detected indirectly, primarily through methods like observing stellar dimming (the “transit method”). Less than 2% of exoplanets have been directly imaged, highlighting Webb’s advanced capabilities. Remarkably, despite its size, this new exoplanet is the least massive ever discovered through direct imaging, being 10 times less massive than the previous record holder. This speaks volumes about Webb’s instrument sensitivity.

The discovery was made possible by a French-produced coronagraph on Webb’s Mid-Infrared Instrument (MIRI), which blocks out the star’s bright light.

“Webb opens a new window — in terms of mass and the distance of a planet to the star — of exoplanets that had not been accessible to observations so far,” stated Anne-Marie Lagrange, lead author of the study published in Nature. “This is important to explore the diversity of exoplanetary systems and understand how they form and evolve.”

The planet orbits its host star, TWA 7, at a distance about 52 times greater than Earth’s orbital distance from the sun (for context, Neptune orbits roughly 30 times further than Earth). Indirect methods are more effective for planets closer to their stars, making direct imaging crucial for distant ones. “Imaging is needed to robustly detect and characterize planets further away,” Lagrange explained.

Both TWA 7 and its planet are incredibly young, estimated at only about six million years old, compared to our sun’s 4.5 billion years. The discovery offers insights into planetary formation, which begins with a collapsing cloud of gas and dust forming a star, with leftover material in a protoplanetary disk then forming planets.

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The observation angle (from above) allowed researchers to discern the structure of the remaining disk around TWA 7: two broad concentric ring-like structures of rocky and dusty material, with the new planet residing in a narrow, third ring.

Researchers are still investigating the planet’s atmospheric composition and whether it’s still gaining mass. While this is the smallest exoplanet directly imaged, it’s still far more massive than rocky planets like Earth. Webb, despite its infrared capabilities, cannot yet directly image Earth-sized exoplanets.

“Looking forward, I do hope the projects of direct imaging of Earth-like planets and searches for possible signs of life will become a reality,” Lagrange concluded, envisioning the future of exoplanet exploration.