Oral Presentation

Azimuthal Asymmetries Reveal the Vertical Structure of Protoplanetary Disks

Author(s): Yansong Qian (University of Toronto), Yanqin Wu (University of Toronto)

Presenter: Yansong Qian (University of Toronto)

The thickness of dust disk is a much sought-after property, and inclined systems provide a unique opportunity to study it. Millimeter observations of inclined rings often show brightness asymmetries between the major and minor axes. These asymmetries are commonly interpreted as optical-depth variations induced by projection effects and used to constrain the vertical distribution of dust, under the assumption of optically thin emission. In this talk, I will show that similar asymmetries can arise naturally from beam convolution, even with a circular beam. Motivated by this effect, we develop a method to measure the dust scale height and optical depth using geometric effects alone.
Taking LkCa 15 as a case study, we find that its dust ring must be as tall as the gas and has an optical depth of order unity at 1.3mm. We also find that the dust ring appears taller and wider in shorter wavelengths. These results provide new insights into dust growth.