The discovery of two super-puff planets, TOI-791 b and TOI-791 c, has captivated the scientific community and sparked a frenzy of excitement and curiosity. These planets, with densities lower than cotton candy, are a testament to the wonders of the universe and the ongoing quest to understand planetary formation and evolution.
What makes these planets even more fascinating is their unique orbital arrangement, known as a 5:3 mean-motion resonance. This resonance means that for every five orbits completed by the inner planet, the outer planet completes almost exactly three. This gravitational dance between the planets creates small but measurable changes in the timing of their transits, providing valuable insights into their masses and sizes.
The discovery of these planets was made possible by the tireless efforts of citizen scientists participating in the Planet Hunters TESS project. These volunteers, working alongside professional astronomers, flagged the planets as potential candidates for further study. The project, which searches for signs of unknown worlds in observations collected by NASA's Transiting Exoplanet Survey Satellite (TESS), has been instrumental in the discovery of many exoplanets.
The role of Antarctica in this discovery cannot be overstated. The ASTEP telescope, located at the Concordia Station in Antarctica, provided crucial data for the study. The long winter nights in Antarctica allowed astronomers to observe the planets' unusually long transits, each lasting more than 11 hours, without interruption. These observations, combined with data from telescopes around the world, enabled researchers to determine the planets' sizes and masses, and ultimately, their incredibly low densities.
The formation of super-puff planets remains a mystery, with scientists proposing various theories. One leading explanation suggests that these planets possess enormous atmospheres rich in hydrogen and helium, accounting for a large fraction of their total mass. These thick gaseous envelopes may have formed when the planets were much farther from their star, in colder regions of the protoplanetary disc where gas could rapidly accumulate around a solid planetary core.
The discovery of TOI-791 b and TOI-791 c highlights the importance of continued international collaboration in astronomy. The study, which involved researchers from the University of Oxford, Université Côte d'Azur/Observatoire de la Côte d'Azur, and the University of Birmingham, underscores the value of combining observations from Antarctica, space telescopes, and observatories across several continents. As we continue to explore the cosmos, these discoveries remind us of the endless possibilities and the importance of teamwork in advancing our understanding of the universe.
