Temporal Variations in the Sun's Rotational Kinetic Energy

TL;DR

This study investigates how the Sun's rotational kinetic energy and angular momentum vary over the solar cycle, revealing latitude-dependent correlations with solar activity through helioseismic data analysis.

Contribution

It provides the first detailed analysis of the Sun's rotational kinetic energy variations across latitudes and their relation to solar activity using helioseismic data.

Findings

High-latitude angular momentum correlates positively with solar activity.

Low-latitude angular momentum correlates negatively with solar activity.

Significant temporal variations in gravitational multipole moments are observed.

Abstract

AIM: To study the variation of the angular momentum and the rotational kinetic energy of the Sun, and associated variations in the gravitational multipole moments, on a timescale of the solar cycle. METHOD: Inverting helioseismic rotational splitting data obtained by the Global Oscillation Network Group and by the Michelson Doppler Imager on the Solar and Heliospheric Observatory. RESULTS: The temporal variation in angular momentum and kinetic energy at high latitudes (>\pi/4) through the convection zone is positively correlated with solar activity, whereas at low latitudes it is anticorrelated, except for the top 10% by radius where both are correlated positively. CONCLUSION: The helioseismic data imply significant temporal variation in the angular momentum and the rotational kinetic energy, and in the gravitational multipole moments. The properties of that variation will help constrain dynamical theories of the solar cycle.