Constraining giant exoplanet formation and migration with direct imaging surveys - Henry Ngo (Caltech)

Résumé

Over the past two decades, planet finding surveys have found gas giant exoplanets on orbital separations spanning more than four orders of magnitudes. The giant planets with the smallest semi-major axes were the first planets detected via radial velocity and transit surveys. Known as 'hot Jupiters', these giant planets can have orbital semi-major axes as low as 0.01 AU. At the other extreme, recent direct imaging discoveries revealed giant planets beyond their system ice lines, with separations as large as hundreds of AU. However, it is not known whether these two groups of extreme giant planets formed in situ or if they instead formed at moderate distances and then migrated to their current locations. I will present two direct imaging surveys to explore the origins and to characterize the population of these extreme gas giant planets. The first survey focuses on the influence of stellar companions on hot Jupiter formation and migration. Our work shows that stellar companions are unlikely affect hot Jupiter migration but they may have an important role in giant planet formation. The second study searches for directly imaged giant planets near their system ice lines. We will compare our imaged giant population with the radial velocity detected giant planets to compare formation mechanisms. We are able to access these small separations for the first time using the new vortex coronagraph recently installed on Keck/NIRC2.