A 3-dimensional model of tangential YORP

TL;DR

This paper introduces the first 3D model of tangential YORP (TYORP), incorporating shadowing and self-illumination effects, to better understand its influence on asteroid rotation, showing it is smaller but comparable to normal YORP.

Contribution

The study develops a comprehensive 3D model of TYORP, including shadowing and self-illumination, advancing beyond previous simplified 1D models.

Findings

TYORP torque is smaller than previous estimates but still significant.

TYORP is comparable in magnitude to normal YORP torques.

Model parameters influence TYORP dependence significantly.

Abstract

Tangential YORP, or TYORP, has recently been demonstrated to be an important factor in the evolution of an asteroid's rotation state. It is complementary to normal YORP, or NYORP, which used to be considered previously. While NYORP is produced by non-symmetry in the large-scale geometry of an asteroid, TYORP is due to heat conductivity in stones on the surface of the asteroid. Yet to date TYORP has been studied only in a simplified 1-dimensional model, substituting stones by high long walls. This article for the first time considers TYORP in a realistic 3-dimensional model, also including shadowing and self-illumination effects via ray tracing. TYORP is simulated for spherical stones lying on regolith. The model includes only 5 free parameters, and the dependence of the TYORP on each of them is studied. The TYORP torque appears to be smaller than previous estimates from 1-dimensional model, but still comparable to the NYORP torques. These results can be used to estimate TYORP of different asteroids, and also as a basis for more sophisticated models of TYORP.