In a significant astronomical discovery, a pair of newly identified planets, known as superpuffs, have been found orbiting a sunlike star named TOI 791, located approximately 1,113 light-years from Earth. These planets are remarkable for their size, being comparable to Jupiter, yet they possess less than 6 percent of Jupiter's mass. This discovery was made possible by the Transiting Exoplanet Survey Satellite (TESS), which detected the planets as they transited in front of their host star, blocking some of its light. The measurements of the planets' radii were determined to be 0.993 and 1.155 times that of Jupiter, indicating their substantial size despite their low mass.
To ascertain the density of these planets, astronomers needed to calculate both their size and mass. The orbits of the planets provided crucial data, as they influence each other's gravitational pull. Dransfield and his team monitored the planets' orbits over several years using the Antarctic Search for Transiting ExoPlanets telescope (ASTEP). The resulting densities were found to be 0.038 and 0.047 grams per cubic centimeter, which is notably less than that of cotton candy, which has a density of about 0.05 grams per cubic centimeter. This finding positions these planets as the lightest known Jupiter-sized planets.
The formation of these superpuff planets raises intriguing questions among astronomers. One prevailing theory suggests that they may have originated far from their star and migrated inward, causing their atmospheres to heat up and expand. However, theoretical astrophysicist Anthony Piro has proposed that the presence of giant ring systems could also contribute to their apparent size, although he dismisses this explanation for the current pair of planets, citing the improbability of two such planets existing around the same star. The rapid spin of the host star may indicate its youth, suggesting that these superpuffs could still be in a cooling phase and may contract as they age.
The next phase of research involves utilizing the James Webb Space Telescope to analyze the composition of these planets, which could provide further insights into their origins and the processes involved in planetary formation. Dransfield emphasizes the importance of discovering such rare planets, as they can enhance our understanding of planetary evolution and the diverse outcomes possible in the cosmos. This knowledge ultimately helps contextualize Earth within the broader universe, shedding light on the complexities of planetary systems and their development over time.
