Contribution Review talk
The Physics and Chemistry of Gas Rich Disks from Young to Old
In this talk I will review our current, and evolving, understanding of the physics and chemistry of gas rich disks, including the youngest stages as the disk is forming. The record of the earliest stages of disk formation is only now being constrained and it is an open question as how much of the initial chemical composition is altered during this stage. In this light, I will discuss key aspects of this stage including the variability of accretion and the potential for disk formation to alter the composition inherited from the cold quiescent pre-stellar phase. At the Class II stage, disks are exposed to both stellar and interstellar UV/X-ray radiation along the the potential presence of galactic cosmic rays, which heats disk surfaces, provides ionizing agents to power chemical reactions, and links the neutrals to magnetic fields. We will summarize what is known about the propagation of these agents, including a discussion of the penetration of galactic cosmic rays. The resulting chemistry is dominated by the formation of simple species for which we now have a host observational constraints from spatially unresolved data and a growing body of resolved detections from ground-based interferometers. Thus, we will discuss how observations of simple species are potentially revealing dominant effects in the overall chemistry, while potentially setting limits on the formation of complex organics.
As astrochemists we aim to explore the chemical composition associated with planet formation. In the current age of ALMA we must now begin to link our astronomical understanding to that of the record the solar system and beyond. Thus, where possible, I will discuss potential links to the our knowledge regarding the formation and chemistry of small and large bodies in the solar system along with giant planets in other planetary systems.