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... Show moreStar 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. Show less
Stars form as a result of gravitational collapse of an interstellar molecular cloud. In the process, a circumstellar disk, often referred to as a protoplanetary disk, is formed as well as a result... Show moreStars form as a result of gravitational collapse of an interstellar molecular cloud. In the process, a circumstellar disk, often referred to as a protoplanetary disk, is formed as well as a result of the net angular momentum of the parental cloud. This thesis addresses several questions about the formation of this disk and, in particular, the evolution of the velocity field surrounding the young star. The composition of the velocity field (i.e., the ratio of infall to rotation) can be use to trace the evolution of young stellar objects. This method of characterizing the evolutionary stage of protostars is applied to two objects, NGC1333-IRAS2A and L1489 IRS, the first of which we find to be a very young object while the latter is significantly more evolved. In addition, one chapter of this thesis presents a new radiation transfer code which has been developed by the author. Show less
