Imaging Forming Planetary Systems Towards Imaging Exo-Earths

Abstract

Thousands of exoplanets have been discovered, although very few have been directly observed. Direct imaging and spectroscopy of the thermal or reflected light from exoplanets offers distinct and complementary information to that gained by indirect methods of detection and, in the future, may enable detailed characterization of the atmospheres of Earth-like planets around nearby Sun-like stars. As the instru- mentation progresses, improvements to on-sky performance are enabling scientific capabilities that were previously impossiblesuch as imaging young giant planets and the environments in which they form. In this thesis, I present my work on ground- based imaging of young planetary systems, including several looks into individual planetary systems in formation, a holistic analysis of the planets discovered so far by direct imaging, and a roadmap toward imaging lower-mass exoplanets. I begin by presenting one of the first results from a new class of adaptive optics systems: the discovery of a two-armed spiral disk with the VLT, followed by an orbital monitoring study showing that the systems low-mass stellar companion is responsible for the two-armed spiral structure. I then present a deep thermal imaging study of another young spiral disk with the LBT, and report the detection of a candidate giant planet matching many properties of the predicted planet. I then present results of optical imaging of PDS 70b with MagAO, which enabled one of the first mass accretion rate measurements of a young giant planet inside of a gapped- disk. Finally, I present a holistic study of the planets and brown-dwarf companions discovered by direct imaging to date, including a direct measurement of the wide- orbit planetary mass function. I conclude with an outlook for what the next years of exoplanet imaging may bring, and discuss how we will continue towards imaging exo-Earths.