Imaging Protoplanets with Adaptive Optics and Interferometry

For decades, astronomers have used observations of mature planets to inform our understanding of planet formation, beginning with our own solar system and now with the thousands of known exoplanets. While this has placed general constraints on the planet formation process, many open questions remain. Evincing the details of how planets grow and accrete, and how they interact with their natal environments, requires direct observations of forming planets themselves. Compared to mature planets, protoplanets are expected to have low contrasts relative to their host stars in the infrared. However, nearby star forming regions lie at much greater distances (~150 pc) than typical directly imaged planets (~10 pc). Protoplanets on orbits of several AU will be at or within the diffraction limit of 8-meter class telescopes, necessitating novel imaging techniques even beyond high performance coronagraphs. The technique of non-redundant masking (NRM), which turns a conventional telescope into an interferometric array, is well suited for direct protoplanet detection. I will present the results of NRM protoplanet searches in transition disks - protoplanetary disks with inner clearings that may be shaped by forming planets. I will then describe a related interferometric technique, kernel phase, which will enable simultaneous protoplanet detection and characterization using integral field spectrographs. Lastly, I will discuss prospects for protoplanet detection and characterization using interferometry and spectroscopy on the next generation of instruments and telescopes.