A Theory on the Convective Origins of Active Longitudes on Solar-like Stars

TL;DR

This paper presents a model showing that giant convective cells in stars can cause persistent, preferred longitudes of magnetic flux emergence, explaining observed active longitudes on the Sun and similar stars.

Contribution

It introduces a thin flux tube simulation demonstrating how giant convective cells influence flux emergence patterns, linking convection dynamics to active longitudes.

Findings

Flux emergence is inhomogeneous in longitude.

Emergence patterns exhibit low-order preferred modes.

Active longitudes drift and align across the Equator.

Abstract

Using a thin flux tube model in a rotating spherical shell of turbulent, solar-like convective flows, we find that the distribution of emerging flux tubes in our simulation is inhomogeneous in longitude, with properties similar to those of active longitudes on the Sun and other solar-like stars. The large-scale pattern of flux emergence our simulations produce exhibits preferred longitudinal modes of low order, drift with respect to a fixed reference system, and alignment across the Equator at low latitudes between 15 degrees. We suggest that these active-longitude-like emergence patterns are the result of columnar, rotationally aligned giant cells present in our convection simulation at low latitudes. If giant convecting cells exist in the bulk of the solar convection zone, this phenomenon, along with differential rotation, could in part provide an explanation for the behavior of active longitudes.