Thermal Flipping of Interstellar Grains

TL;DR

This paper challenges the prevailing view that internal relaxation causes thermal flipping in interstellar dust grains, showing that thermal flipping is not possible under certain conditions.

Contribution

It demonstrates that thermal flipping cannot occur if the inertia tensor remains constant over time, revising previous assumptions in grain alignment theory.

Findings

Thermal flipping is impossible when the inertia tensor is static.

Internal relaxation alone does not induce thermal flipping.

Implications for models of grain alignment in space.

Abstract

In interstellar dust grains, internal processes dissipate rotational kinetic energy. The dissipation is accompanied by thermal fluctuations, which transfer energy from the vibrational modes to rotation. Together, these processes are known as internal relaxation. For the past several years, internal relaxation has been thought to give rise to thermal flipping, with profound consequences for grain alignment theory. I show that thermal flipping is not possible in the limit that the inertia tensor does not vary with time.