Produced by: Tarun Mishra
The James Webb Space Telescope (JWST) successfully captured images of AF Leporis b, the lowest-mass exoplanet it has observed so far. This planet, located 88 light-years from Earth, is also the closest to its parent star to be directly observed by JWST.
Astronomers faced a time-sensitive challenge as AF Lep b was nearing the point where it would disappear behind the blinding light of its host star. This could have made the planet unobservable for up to a decade.
AF Lep b, a planet about 3.2 times the mass of Jupiter, set records in 2023 as the lowest-mass exoplanet detected through direct observation and the lowest-mass planet with its mass measured via astrometry. Astrometry tracks star movements to identify gravitational wobbles caused by orbiting planets.
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AF Lep b is just 23 million years old, making it a very young planet compared to Earth, which is around 4.6 billion years old. Its large size and proximity to its star made it a prime candidate for JWST’s observation capabilities.
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Due to its long wavelengths, JWST faces limitations when distinguishing between objects that are close together. However, using a coronagraph, which blocks out much of the star's light, JWST was able to image AF Lep b despite these challenges.
Observations revealed an active atmosphere on AF Lep b, with convection currents stirring gases between its lower and upper layers. The team also detected unexpectedly high levels of carbon monoxide, possibly brought up by strong updrafts.
The planet is currently about eight times the distance between Earth and the Sun from its star. As it moves closer, more light from the star will block JWST’s view, making it impossible to observe with current technology until it re-emerges in about 10 years.
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The success of this observation highlights JWST’s ability to push boundaries in exoplanet research. The mission also foreshadows future discoveries, with more detailed studies of newly discovered planets expected in the coming years. The research has been published in the Astrophysical Journal.