Rotational Disruption of Dust and Ice by Radiative Torques in
  Protoplanetary Disks and Implications for Observations
  Dust and ice mantles on dust grains play an important role in various
processes in protoplanetary disks (PPDs) around a young star, including
planetesimal formation, surface chemistry, and being the reservoir of water in
habitable zones. In this paper, we will perform two-dimensional modeling of
rotational disruption of dust grains and ice mantles due to centrifugal force
within suprathermally rotating grains spun-up by radiative torques for disks
around T-Tauri and Herbig Ae/Be stars. We first study rotational disruption of
large composite grains and find that large aggregates could be disrupted into
individual nanoparticles via the RAdiative Torque Disruption (RATD) mechanism.
We then study rotational desorption of ice mantles and ro-thermal desorption of
molecules from the ice mantle. We will show that ice mantles in the warm
surface layer and above of the disk can be disrupted into small icy fragments,
followed by rapid evaporation of molecules. We suggest that the rotational
disruption mechanism can replenish the ubiquitous presence of polycyclic
aromatic hydrogen (PAHs)/ nanoparticles in the hot surface layers of PPDs as
observed in mid-IR emission, which are presumably destroyed by extreme
ultraviolet (UV) stellar photons. We show that the water snowline is more
extended in the presence of rotational desorption, which would decrease the
number of comets but increase the number of asteroids formed in the solar
nebula. Finally, we suggest that the more efficient breakup of carbonaceous
grains than silicates by RATD might resolve the carbon deficit problem measured
on the Earth and rocky bodies.
