Millimeter emission from protoplanetary disks : dust, cold gas, and relativistic electrons

Star formation occurs when a dense cloud of interstellar gas and dust gravitationally collapses. Rotation during this collapse leads naturally to the formation of a flattened circumstellar disk around the forming star. These disks are additionally known as protoplanetary disks because the orbiting circumstellar dust and cold gas represent the building blocks for planets. How long this material survives and how it evolves in this time will determine the propensity for (and the diversity of) planetary systems. This thesis is split into three parts that analyze different aspects of disk evolution and the circumstellar environment. In part one, we use observations at millimeter wavelengths to probe (and then model and compare) the dust and gas properties around low-mass Sun-like stars. We conclude that high-resolution spatial and spectral imaging of optically thinner molecular lines will provide the most robust description of the disk structure and evolution using future instrumentation. During these routine observations, we report recurring millimeter flares resulting in part two. We attribute this phenomenon to synchrotron emission from relativistic electrons trapped in the (colliding) magnetospheres of a young binary system. Finally, we present a microgravity experiment to probe the collisional growth mechanism for the first steps of planet formation