Response to "Concerning Thermal Tides on Hot Jupiters" (Goodman 2009; arXiv: 0901.3279)

TL;DR

This paper demonstrates that thermal tides can induce significant quadrupole moments in hot Jupiters, potentially causing asynchronous rotation and explaining their inflated radii and eccentric orbits.

Contribution

It provides an idealized analysis showing thermal forcing can generate quadrupoles and torques, challenging previous claims and supporting a mechanism for hot Jupiter characteristics.

Findings

Thermal forcing can induce significant quadrupole moments.

Quadrupoles can be oriented to torque planets away from synchronous rotation.

Supports thermal tide mechanism for hot Jupiter phenomena.

Abstract

Motivated by the comments of Goodman (2009) on our paper concerning thermal tides (Arras and Socrates 2009a), we have studied an idealized problem to understand the global response of a completely fluid gas giant planet to thermal forcing at the surface (Arras and Socrates 2009b). Our findings disagree with the main claims in Goodman (2009). We find that significant quadrupole moments can indeed be induced as a result of thermal forcing. Furthermore, we find that it is possible for the orientation of the quadrupoles to be such that the planet is torqued away from synchronous rotation. Given these results, we believe our proposed thermal tide mechanism (Arras and Socrates 2009a) provides a viable scenario for generating steady-state asychronous rotation, inflated radii and possibly eccentric orbits of the hot Jupiters.