Space Climate 7 Meeting Abstract
On the solar dynamo-wind feedback loop
Antoine Strugarek (CEA Saclay-DAp/AIM)
B. Perri and A.S. Brun
The magnetic field of our Sun is generated through an internal dynamo process leading to a cyclic variability of about 11 years. The cyclic field shapes the environment of our star and determines the connectivity in the heliosphere from the photosphere to the Earth orbit and beyond. Indeed, the solar wind is known to be modulated along the magnetic cycle of the Sun with very different wind speed distributions along the helio-latitude between solar maximum and minimum. Conversely the environment of the Sun influences its dynamo process by setting its boundary conditions (e.g. the allowed field topology and helicity flux) at the solar surface. Quasi-static studies have begun to unveil part of this feedback-loop through the characterization of the influence of the dynamo field on the wind distribution. Nevertheless, the full interplay between the two still eludes our understanding. We present an ongoing effort to model the dynamical coupling between the dynamo-generated magnetic field of the Sun and the heliosphere. We use the compressible magnetohydrodynamical code PLUTO to compute simultaneously in 2.5D the generation and evolution of magnetic field inside the star via an alpha-omega dynamo process, and the corresponding evolution of the corona over a solar-like 11-year cycle. A multi-layered boundary condition at the surface of the star connects the inner and outer stellar layers, allowing the feedback-loop to operate. We focus our analysis on the influence of the dynamo field on the magnetic topology and connectivity in the heliosphere, and recover qualitatively the solar wind speed distribution at cycle maximum and minimum. We further assess the impact of the solar wind on the dynamo itself by comparing our result with classical alpha-omega models with simpler potential field boundary conditions. Finally, we give perspectives to incorporate more advanced mean-field models of the solar dynamo by considering the Babcock-Leighton effect. Overall our model gives us a new tool to better understand the Sun-Earth connection at various phases of the solar cycle in a space weather perspective.
Mode of presentation: oral (Need to be confirmed by the SOC)