http://arxiv.org/abs/1812.08391
Interstellar dust is an essential component of the interstellar medium and plays critical roles in astrophysics. Achieving an accurate model of interstellar dust is therefore of great importance. Interstellar dust models are usually built based on observational constraints such as starlight extinction and polarization, but dynamical constraints such as grain rotation are not considered. In this paper, we show that a newly discovered effect by Hoang et al., so-called RAdiative Torque Disruption (RATD), due to centrifugal stress within suprathermally rotating grains spun-up by radiative torques (RATs) is an important dynamical constraint for dust models. Using this dynamical constraint we will derive the maximum grain size for four different grain models, including a contact binary, a composite grain, a silicate-core and icy amorphous carbon mantle, and compact model for the different radiation fields. We find that the different dust models have different the maximum size due to their different tensile strengths, and the largest maximum size corresponds to compact grains, strongest grain structure. We show that the composite grain model cannot be ruled out if constituent particles are small with radius $a_{p}\le$ 25 nm, but large composite grains would be destroyed if the particles are large with $a_{p}\ge 50$ nm. Finally, we suggest that grain internal structures can be constrained with observational data by using RATD effect.
T. Hoang
Fri, 21 Dec 18
2/72
Comments: 11 pages, 4 figures
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