Göttingen 2025 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

EP: Fachverband Extraterrestrische Physik

EP 13: Astrophysics I

EP 13.5: Vortrag

Freitag, 4. April 2025, 10:15–10:30, ZHG101

3D Resistive MHD Perspectives on the Localized Dynamics at the Apex of an Astropause — •Kuljeet Singh Saddal^1,2, Dieter Nickeler¹, and Rodrigo Meneses³ — ¹Astronomický ústav AV CR, Ondřejov, Czech Republic — ²Charles University, Faculty of Mathematics and Physics, Praha, Czech Republic — ³Universidad de Valparaíso. General Cruz 222, Valparaíso

The dynamical interaction zones where stellar winds collide with the interstellar medium, known as astrospheres, are characterized by complex hydrodynamic (HD) or magnetohydrodynamic (MHD) discontinuities. Central to this interaction is the astropause, a boundary separating stellar wind and interstellar flows, whose structure is governed by fluid flow separatrices. In the MHD framework, the presence of a magnetic null point and a velocity stagnation point near the apex of the astropause is essential. Assuming these points coincide, we derive exact solutions to the resistive MHD equations in three-dimensional space. The topology of the magnetic field and two free parameters describes the nature of these solutions. We identify flows that traverse the magnetic field separatrices, i.e., the fan plane and spine line, potentially enabling the identification of true reconnective solutions. The goal of this analysis is to identify and differentiate reconnective and non-reconnective solutions based on specific criteria. Using these solutions, we calculate dissipation rates and derive thermodynamic properties, such as pressure and temperature, at the apex. This enables the computation of radiance and the generation of synthetic sky maps for comparison with observational data.

Keywords: Magnetohydrodynamics; Astrospheres; Magnetic Reconnection; Topological fluid dynamics