Exploring ‘Rogue Planets’ with JWST
Ray Jayawardhana (York University)
NIRISS Science Team
Deep surveys in nearby star-forming regions have revealed sub-stellar objects down to very low masses, and have begun to determine their characteristics. Results to date suggest that brown dwarfs likely represent the extension of the stellar mass function. However, surveys with follow-up spectroscopy tend to be incomplete below ~10 M_Jupiter, and particularly below ~5 M_Jupiter. A large population of `rogue planets,’ formed in disks around nascent stars and then ejected, is expected in young star clusters. With the James Webb Space Telescope, we will be able to search for and confirm such free-floating siblings of giant exoplanets for the first time. In particular, our GTO program, using the Wide-Field Slitless Spectroscopy mode of NIRISS, will be able to identify, confirm and perform basic characterization of young planetary-mass sub-stellar objects in one go, making it a compelling and exciting early science initiative for JWST. We outline the planned observations, and discuss the implications of this first direct exploration of Jovian-mass rogue planets for star and planet formation.