Understanding planet formation with ALMA and EVLA

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Over 450 extrasolar planets are now known, and planets have recently been directly imaged around two stars. Although we know that planets must form in protoplanetary disks of gas and solids around forming stars, the actual process by which planets are built up in disks is not yet known. The completion of two high-resolution telescope arrays, ALMA (Atacama Large Millimeter-submillimeter Array) in northern Chile and the EVLA (Expanded Very Large Array) in New Mexico will enable us to image the process of planet formation for the first time using high-resolution studies of the detailed structures within protoplanetary disks. The combination of these instruments is ideal for tracing the onset of planet formation, when micron-sized particles start to agglomerate into larger pebbles. We will search for evidence of these pebbles to determine when and where the onset of planet formation occurs. Our observations will reveal whether special conditions are needed to start the build up of pebbles or whether the process is robust and occurs throughout the disks. Comparison of disks in different regions will reveal whether the environment in which stars forms impacts the formation of planets around them. We will also observe older disks by which time planetary mass bodies must have formed. Planets in the final stages of formation could be directly imaged within disks, and many more will be revealed by the gaps and holes that form due to the interaction of the planet with material in the disk. Where we find evidence of planets, we will take detailed observations of the gas content to learn what the atmospheres of forming planets could contain. With all these data in hand, we will soon better understand the formation of our own Solar System, the Earth and perhaps even life itself.