Exoplanet System Ages from Galactic Kinematics and their Impact on Planet Formation and Evolution

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A research group of faculty and students from Johns Hopkins University will measure the ages of planets orbiting nearby stars. Many questions related to planet formation and evolution cannot be answered without a better understanding of planet ages. It is understood that both stars and their planets have the same age, however most of the usual ways to infer stellar ages fail for stars that host planets, so new approaches must be taken. The awarded investigation will apply a new method to derive ages for populations of stars. This new technique will then be used to identify why some planetary systems are different from our own. This research program will provide internships for STEM undergraduates from Morgan State University as well as Johns Hopkins University, and it will form the basis for a PhD thesis. In addition, this group will start a program of portable planetarium visits to several Baltimore City Enoch Pratt Public Library branches. The difficulty of estimating exoplanet host star ages is a major problem preventing progress in understanding planet formation and evolution. Traditional isochrone, asteroseismic, gyrochronological, stellar activity-based, or lithium-based age estimates are unreliable or unavailable for most planet host stars, so new approaches must be taken to solve the problem of exoplanet host star ages. As a thin disk stellar population ages, its constituent stars experience random kicks due to interactions with molecular clouds, transient disk features, and the Galactic bar. The investigation will make use of the Galactic velocity dispersion of a thin disk stellar population as a proxy for exoplanet age. The investigation will use this Galactic velocity dispersion technique to calculate relative ages for exoplanet host stars with different characteristic, as well as stars without planets, to explore planet formation and evolution. The application of the Galactic velocity dispersion technique for exoplanets could reveal the origin of significant stellar obliquities in exoplanet systems, the origin and fate of ultra-short orbital period planets, and the reason that multiple-planet systems are often observed just wide of mean-motion resonances.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.