'Super-puff' planets lighter than candy floss discovered by international team - Nanowerk

An international team, primarily led by the University of Oxford, has just announced the discovery of two 'super-puff' planets, TOI-791 b and TOI-791 c, that are so incredibly light they're less dense than candy floss. These Jupiter-sized gas giants, orbiting a distant star 1,110 light-years away, are among the lightest ever detected, presenting a significant puzzle for scientists trying to understand how planets form and evolve. This groundbreaking finding, published today in Monthly Notices of the Royal Astronomical Society, challenges current planetary formation models. The exoplanets were first spotted as candidates by citizen scientists combing data from NASA's Transiting Exoplanet Survey Satellite (TESS). Eight years of intricate follow-up observations, including crucial uninterrupted sessions from the ASTEP telescope in Antarctica during its months-long winter darkness, allowed researchers to precisely measure their sizes and masses, confirming their astonishingly low densities and revealing they're locked in a rare 5:3 mean-motion resonance. The existence of two such wispy worlds in a single system makes TOI-791 an exceptionally rare 'laboratory' for astronomers. While theories suggest these planets likely possess vast atmospheres of hydrogen and helium that somehow prevented collapse, the exact mechanisms remain debated. Scientists are now planning to use the powerful James Webb Space Telescope to probe the chemical makeup of their atmospheres, hoping to unlock deeper insights into how these 'super-puff' enigmas came to be and what it means for our broader understanding of cosmic evolution.