The James Webb Space Telescope (JWST) has successfully captured direct images of AF Leporis b, marking it as the lowest mass exoplanet observed outside the solar system to date. This planet is also the closest to its star to be directly imaged by the $10 billion telescope.
The imaging process was described as a "race against time" as AF Lep b was on the verge of disappearing behind the intense light of its parent star, potentially for a decade. At just 23 million years old, AF Lep b is significantly younger than Earth, which is approximately 4.6 billion years old. It boasts a mass around 3.2 times that of Jupiter and a diameter about 1.2 times greater than that of the solar system's gas giant.
Researchers faced challenges due to the planet's proximity to its star, which complicates observations. Kyle Franson from the University of Texas at Austin noted that JWST is smaller than the largest ground telescopes, making it difficult to distinguish between closely positioned celestial bodies.
AF Lep b is located 88 light-years from Earth, presenting as a mere speck to the JWST. However, astronomers can extract significant information from this observation. Since the first exoplanet was discovered in the 1990s, the catalog has expanded to over 6,000 entries, yet very few have been directly imaged.
Most exoplanets are detected through their interactions with their host stars, either by blocking light or through gravitational influences. The JWST employs a coronagraph to block starlight, allowing for clearer observation of orbiting planets. AF Lep b, being a young planet, has a strong glow, making it an ideal candidate for such imaging.
The research team aimed to study the atmosphere of AF Lep b, as planets with similar masses to solar system gas giants are uncommon. However, they had to act swiftly, as the planet’s orbit is moving closer to its star, limiting observation time. With its 25-Earth-year orbit, it could take over a decade for AF Lep b to reappear from behind its star.
Observations revealed that AF Lep b has a highly active atmosphere, with convection currents mixing elements between its lower and upper layers. The team detected unexpectedly high levels of carbon monoxide, suggesting that strong updrafts are responsible for transporting this gas into the planet's upper atmosphere.
This successful imaging not only provides insights into AF Lep b but also demonstrates the JWST's capabilities, exceeding initial expectations. The findings underscore the potential for future discoveries as the JWST continues its mission.