HCS background magnetic field study HYTARO+

Dpt. of Physics and Mathematics, University of Alcalá, Alcalá de Henares, Spain
e-mail: david.arrazola@uah.es

Received: 21 November 2022
Accepted: 24 July 2023

Abstract

Context. HYTARO+ is an analytical model developed to evaluate the influence of the solar magnetic dipole in the topology of the local structure of the heliospheric current sheet (HCS).

Aims. Statistical methods such as MVA, which are typically used in the study of the HCS come with two limitations. On one hand, they do not provide any information about the physical properties of the current sheet and, on the other, they do not offer the possibility of defining the local structure of the HCS from the physical conditions that prevail in the two sectors that separate the sheet. HYTARO model describes the interaction between the magnetic field that defines the structure of the current sheet and the plasma confined within it. HYTARO+ goes deeper into the study of the background magnetic field that is included in the HYTARO model with the aim of identifying its source.

Methods. Multipole expansion is used to provide a general approach to any physical phenomenon of some system, thereby allowing for a potential function representation. In our case, we considered the dipolar and quadrupolar Sun magnetic field contribution in the HCS.

Results. In the development of the HYTARO+ model, we estimated the components of the dipole and quadrupole magnetic fields at 1 AU. In the present study, we establish that the Z component of the dipole field and the X component of the quadrupole field are the more relevant terms of the background field present in the data that correspond to the discontinuities. A summary of the contribution of the multipolar components along the 23 solar cycle is incorporated.