Dust Rotational Dynamics and Stellar Feedback

Very large molecules, nanoparticles, and dust grains (hereafter referred to as cosmic dust) play important role in astrophysics. I study how cosmic dust interact with ambient environments, spun-up to rapid rotation, and the resulting effects of superfast grain rotation on the grain structure and molecules frozen on the grain surface. We identified important effect of stellar feedback from cosmic transients including supernova, Gamma-ray burst, and kilonova on surrounding dust.

Rotational Disruption of Grains by Radiative Torques

Hoang et al. discovered that grains near a strong radiation source can be spun-up to extremely fast rotation at billion rounds per second, such that centrifugal force can instantaneously disrup the grain into small fragments. This is a new mechanism to destroy dust grains by strong radiation fields based on the principle of centrifugal force within a spining body, which we term Radiative Torque Disruption (RATD) mechanism. We are exploring many effects of centrifugal force due to rapid rotationi.

Thiem Hoang Tram Le Ngoc, Hyeseung Lee, and S-H. Ahn, Rotational Disruption of dust grains by Radiative Torques in strong radiation fields, 2019, Nature Astronomy, published on May 6

Thiem Hoang, A dynamical constraint on interstellar dust models from radiative torque disruption, 2019, ApJ, 876, 13

Rotational Disruption of Nanoparticles in Shocks

We study rotation of nanoparticles in shocks and discovered that smallest nanoparticles are disrupted by centrifugal forces due to extremely fast rotation.

Thiem Hoang, Tram Le Ngoc, Dust Rotational Dynamics in C-shocks: Rotational Disruption of Nanoparticles by Stochastic Mechanical Torques and Spinning Dust Emission, ApJ, in press

Tram Le Ngoc, Thiem Hoang, Dust rotational dynamics in CJ-shocks: rotational disruption of nanoparticles by stochastic mechanical torques and spinning dust emission 2019, submitted

Rotational Desorption of Complex Molecules from Grain Surface

We study the effect of suprathermal rotation on desorption of molecules from the grain surface in star-forming regions. We discover a new process that can desorb molecules at lower temperatures than the popular thermal desorption mechanism.

Thiem Hoang, Ngo Duy Tung, Chemistry on Rotating Grain Surface: Ro-Thermal Desorption of Molecules from Ice Mantles, submitted to ApJ

Thiem Hoang, Tram Le Ngoc, Rotational Desorption of Ice Mantles and Complex Molecules from Suprathermally Rotating Grains around YSOs, submitted, 2019, submitted