Professor Akimasa Kataoka of the National Astronomical Observatory of Japan will be the virtual speaker at an upcoming Department of Physics and Astronomy colloquium. His talk is titled, "Measuring the Grain Size in Protoplanetary Disks by ALMA Polarization Observations."
Dust coagulation is the first stage of planet formation, and observational constraints on the grain size in protoplanetary disks are essential for unveiling planet formation. We are tackling this task by using ALMA polarimetric observations. While polarization has been used for finding the direction of magnetic fields, we have shown that this is not the case in protoplanetary disks; the major process of the polarization is due to self-scattering of thermal dust emission. This new mechanism reveals that dust grains have a size of ~100 micron in protoplanetary disks. This contradicts a common assumption of millimeter to centimeter grains inferred from spectral index measurements. In this talk, Kataoka would like to discuss the basic mechanisms of the self-scattering polarization and implications to planet formation through the grain size measurements.
Meeting number (access code): 120 458 5210
Meeting password: kxPTJCP?462
Department of Physics and Astronomy