Super-puff planets defy planetary formation models
Two newly discovered exoplanets, TOI-791b and TOI-791c, are rewriting what scientists thought possible about planetary formation. Detected by NASA's TESS mission over seven years of observations, these Jupiter-sized planets have densities comparable to cotton candy — or, as one researcher put it, 'a nice blob of shaving foam fresh from the can.' TOI-791b is nearly Jupiter's size but contains only 3% of its mass, while TOI-791c is even larger yet holds just 5.9% of Jupiter's mass.
Seven years of data capture rare system
The planets orbit a Sun-like star called TOI-791, located 1,113 light-years away in the southern constellation Volans. Their long orbital periods — 139 days for TOI-791b and 232 days for TOI-791c — required TESS to accumulate 1,122 days of observations over seven years. The planets' gravitational tug on each other caused subtle timing variations in their transits, allowing astronomers to calculate their masses and confirm their extraordinarily low densities.
Webb Space Telescope to probe atmosphere
The research team, led by the University of Oxford's Dr. Georgina Dransfield and including scientists from the University of Birmingham and NASA's Ames Research Center, has proposed follow-up observations using the James Webb Space Telescope. Webb will analyze the planets' atmospheres for carbon, nitrogen, and oxygen compounds — key clues to understanding how these strange worlds formed. The findings were published in the Monthly Notices of the Royal Astronomical Society.