Ajay Tannirkulam
Michigan
University of Florida Astronomy Colloquium - Feb. 13, 2008
A Comprehensive Study of Proto-Planetary Disks around Herbig Ae/Be stars using Long-Baseline Infrared Interferometry
Planetary systems are born in circumstellar disks around young stellar objects (YSOs) and the disk is thought to play a major role in the evolution of planetary systems. A good understanding of disk structure and its time evolution is therefore essential in comprehending planet formation, planet migration and the diversity of planetary systems. In this thesis, I use high angular resolution observations and state-of-the-art radiative transfer modeling to probe circumstellar disk structure and validate current disk models. First, I discuss models and observations of the gas-dust transition region in YSOs. The dust component in circumstellar disks gets truncated at a finite radius from the central star, inside of which it is too hot for dust to survive. The truncated disk forms an "evaporation front" whose shape depends sensitively on dust properties. The possibility of using the front as a probe of the dust physics operating in circumstellar disks is explored. The CHARA near-infrared (near-IR) array is used to resolve out the evaporation front in the Herbig Ae stars MWC275 and AB Aur, and the presence of an additional near-IR opacity source within the "conventional" dust destruction radius is reported. Second, I describe comprehensive disk models that simultaneously explain the SED (from UV to milli-meter ) and long-baseline interferometry (from near-IR to mm) of Herbig Ae stars. The models are constrained with a wide range of data drawn from the literature as well as new observations made for this study. Specifically, new K band interferometry from the CHARA array and new mid-IR interferometry from the novel Keck Aperture Masking Experiment is reported. I will end my talk with a discussion on exciting prospects for measuring the gas-disk morphology on scales of fractions of an AU with the CHARA array, introducing a new powerful tool to understand the "star-disk connection".