Title: Thermal Response of Dust and Gas to Shadows in Protoplanetary Disks

Speaker: Xiaoyi Ma (Peking University)

Time: 14:00pm, July 27, 2026

Location: 3-402, PMO Xianlin Campus

Abstract: Shadows have been observed in more than a dozen protoplanetary disks in scattered light, produced by misaligned or warped inner structures. In some systems, corresponding dips also appear in millimeter continuum emission as well as molecular line emissions, likely tracing the thermal response of dust and gas in disk to these shadows. Since gas and dust rotate in and out of the shadow due to orbital motion, they receive time-dependent heating and cooling. Thus how they response to the shadow depends on the timescales of the dust cooling and dust-gas collisional coupling. We present a one-dimensional framework that models this response by incorporating energy advection, radiative cooling and gas-dust collisional coupling. By solving the coupled gas-dust temperature equations, we show that the hierarchy of cooling and coupling timescales governs both the depth and azimuthal offset of midplane temperature dips. The model identifies distinct thermal regimes and provides a fast method for predicting gas and dust's thermal responses, which can be used to constrain cooling time from observations. More importantly, this model provides a unique thermodynamical way to constrain the Stokes number, a critical dust aerodynamic parameter for planet formation.