Spinning Dust Emission from Wobbling Grains: Important Physical Effects and Implications

Figure 1

Rotational configuration of a triaxial ellipsoid characterized by three principal axes: 𝐚₁, 𝐚₂, and 𝐚₃ in the inertial coordinate system 𝑥𝑦𝑧. Grain angular momentum 𝐉 is conserved in the absence of external torques and directed along 𝑧-axis. The torque-free motion of the triaxial grain comprises the rotation around the axis of major inertia 𝐚₁, the precession of 𝐚₁ around 𝐉, and the wobbling of 𝐚₁ with respect to 𝐉. The dipole moment 𝝁, which is fixed to grain body, moves together with the grain and thus radiates electric dipole emission.