Cosmic processes dictate sub-Neptune sizes and locations

A new study from researchers at Penn State reveals how various cosmic processes shape the formation of sub-Neptunes, which are planets larger than Earth but smaller than Neptune. The study was published in the Astronomical Journal and utilized data from NASA's Transiting Exoplanet Survey Satellite (TESS). It focuses on young sub-Neptunes that orbit close to their stars. These planets have orbits much closer to their stars than Mercury is to the sun. The study aims to uncover how sub-Neptunes can survive intense radiation from their host stars. Many exoplanets discovered so far have close orbits, raising questions about their formation. The researchers specifically examined sub-Neptunes around young stars, which are often difficult to observe due to high levels of radiation and activity. They developed a tool called Pterodactyls over six years to help identify these young planets from TESS data. The findings indicate that the frequency of close-in sub-Neptunes decreases as stars age. Younger stars have fewer sub-Neptunes compared to stars that are a bit older. This may suggest that many sub-Neptunes start farther from their stars and gradually move closer over time. Alternatively, some planets may lose their atmospheres over time due to stellar radiation. The research team hopes to expand their observation window to study planets with longer orbital periods. They are also interested in future missions that could help identify smaller planets, like those in our solar system, to better understand how planetary systems form and evolve. The study involved various experts and received funding from NASA and other organizations. The team emphasizes that discovering more about different planets could change our understanding of planetary formation and the uniqueness of our solar system.