Two newly discovered planets, TOI-791 b and TOI-791 c, are larger than Jupiter yet so light they have densities comparable to cotton candy, according to NASA's TESS mission. While massive planets typically exhibit high densities due to gravitational compression, these 'super-puffs' combine enormous size with incredibly low mass and density, forcing astronomers to re-evaluate the conditions and processes that lead to the formation of such extreme exoplanets.
The Cotton Candy Giants
TOI-791 c, a 'super-puff' planet, is larger than Jupiter but contains only 5.9 percent of Jupiter’s mass, according to science.nasa.gov. Its companion, TOI-791 b, is nearly Jupiter's size but holds only 3.0 percent of Jupiter’s mass. Such extreme mass-to-size ratios fundamentally differentiate these planets from our solar system's gas giants, pointing to unique formation or atmospheric processes. The presence of two such planets in one system suggests a common, unknown evolutionary pathway, challenging the assumption that gravitational compression solely dictates gas giant density.
TESS's Expanding Universe
NASA's Transiting Exoplanet Survey Satellite (TESS) mission identified TOI-791 b and TOI-791 c, which orbit a star 1,110 light-years away, according to the New York Post. TESS proves critical for identifying exoplanets with unusual characteristics, continually expanding our understanding of planetary system diversity.
The Search for Answers
Their baffling low densities, according to NASA, demand a radical rethinking of gas giant formation and evolution. The planets' relatively long orbital periods of 139 and 232 days imply stellar irradiation is not the sole cause for their inflated atmospheres. More intrinsic or complex formation challenges likely exist, suggesting factors beyond stellar irradiation. Future observations will be critical to determine the atmospheric composition and internal structure of these planets, providing clues to their unusual formation.
Further characterization of these planets' atmospheres and internal structures will likely reveal unprecedented insights into the extreme conditions under which such 'super-puffs' can form.
