Angular momentum transport by internal gravity waves III - Wave excitation by core convection and the Coriolis effect

TL;DR

This paper investigates how the Coriolis effect influences internal gravity waves excited by core convection in a 3 solar mass star, revealing its impact on wave behavior and angular momentum transport.

Contribution

It introduces the role of the Coriolis acceleration in wave excitation and angular momentum transfer, using the traditional approximation with Hough functions for rotating stars.

Findings

Coriolis transforms gravity waves into gravito-inertial waves with equatorial amplitude enhancement.

New wave types emerge, mainly conserving vorticity, affecting angular momentum distribution.

The balance between prograde and retrograde waves is altered by rotation effects.

Abstract

This is the third in a series of papers that deal with angular momentum transport by internal gravity waves. We concentrate on the waves excited by core convection in a 3Msun, Pop I main sequence star. Here, we want to examine the role of the Coriolis acceleration in the equations of motion that describe the behavior of waves and to evaluate its impact on angular momentum transport. We use the so-called traditional approximation of geophysics, which allows variable separation in radial and horizontal components. In the presence of rotation, the horizontal structure is described by Hough functions instead of spherical harmonics. The Coriolis acceleration has two main effects on waves. It transforms pure gravity waves into gravito-inertial waves that have a larger amplitude closer to the equator, and it introduces new waves whose restoring force is mainly the conservation of vorticity. Taking the Coriolis acceleration into account changes the subtle balance between prograde and retrograde waves in non-rotating stars. It also introduces new types of waves that are either purely prograde or retrograde. We show in this paper where the local deposition of angular momentum by such waves is important.