Wednesday, January 17, 2007 - 3:15pm
Dr. Dimitry A. Semenov (MPIA):
"Chemistry as a Tool to Study Protoplanetary Disks: A Modeller View"
Abstract. In my presentation, I'll discuss the importance of studying the chemical composition and evolution of protoplanetary disks from a modeler's perspective. These disks are thought to resemble our own Solar system at the earliest and most important evolutionary stage when formation of planets and planetary bodies such as comets, asteroids, and Kuiper Belt objects have been taking place. The planet-forming disks are dynamically active entities that are characterized by a wide range of temperature, density, and intensity of high-energy radiation, thus being an ideal laboratory for producing a great variety of molecular species both in gas phase and on dust surfaces.
First, I'll provide a short overview of the cosmic chemistry: what is known from observations, laboratory studies, and modeling, and what are the hot topics and major difficulties. Next, I'll present the results of observations and modeling of the fractional ionization in protoplanetary disks -- an important quantity believed to regulate the efficiency of accretion processes and thus dynamical evolution of the disks. Second, as transport processes play crucial role in the global disk evolution, I'll talk about the importance of turbulent diffusion for the disk chemistry and how these results are compared with the observational findings. Last, I'll present a consistent chemical and physical model used to constrain basic parameters (size, mass, orientation, abundances, age) of the disk and envelope surrounding a young Herbig Ae star AB Aur.