Origin and Evolution of the Polar Planets

Many planets around distant stars have been found with strange orbits characterized by large differences between the axis of host star rotation and the orbit of the planet. A team led by the Massachusetts Institute of Technology will explore the origins of these planets. The work will yield predictions that are testable with observations by the James Webb Space Telescope. The team will undergo on-site visits to local high schools and middle schools in the Boston metropolitan area, with a focus on the most diverse and economically disadvantaged districts using a portable planetarium system to give engaging astronomy presentations that allow students to experience the wonders of a dark sky without having to travel to a professional planetarium or a remote location. The educational program will be focused on Solar System objects, nearby stars, and planets. The visits will broaden students’ perspectives about Earth’s cosmic context and inspire students to pursue STEM subjects in college. A sizable fraction of the polar planets are warm Neptune- or super-Neptune-sized planets orbiting cool stars. These polar Neptunes share a variety of distinguishing characteristics: moderately eccentric and polar orbits, locations in or near the so-called hot Neptune desert, puffy atmospheres that show evidence for mass loss in many cases, and evidence for exterior massive companion planets in many cases. The team will perform a comprehensive theoretical analysis of the polar to fully understand the origins of both their orbital and physical properties. Analysis will follow the long-term orbital evolution of planets to see whether resonance can explain present-day orbital properties after gigayears of evolution that follow an initial resonance encounter. The team will study the response of the planets’ interiors and atmospheres to tidal heating to explain present-day observations and will couple the orbital and interior models together to derive holistic constraints on the polar Neptunes’ origins and long-term evolution. The work will yield predictions that are testable with atmospheric observations. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.