An Improved Analytical Model of the Local Interstellar Magnetic Field: The Extension to Compressibility

• Published in: The Astrophysical journal Vol. 838; no. 1; pp. 75 - 84
• Main Authors: Kleimann, Jens, Röken, Christian, Fichtner, Horst
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 20.03.2017; IOP Publishing
• Subjects: Adiabatic equations; APPROXIMATIONS; Astrophysics; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; COMPRESSIBILITY; Computational fluid dynamics; Computer simulation; DENSITY; EQUATIONS OF STATE; Flow velocity; Fluid flow; Heliopause; HELIOSPHERE; Incompressible flow; INTERSTELLAR MAGNETIC FIELDS; Magnetic fields; Magnetism; Magnetohydrodynamic simulation; MAGNETOHYDRODYNAMICS; magnetohydrodynamics (MHD); Mathematical analysis; Mathematical models; methods: analytical; Momentum balance; SIMULATION; STREAMS; SUBSONIC FLOW; SUN; Sun: heliosphere; VELOCITY
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/aa5f15

A previously published analytical magnetohydrodynamic model for the local interstellar magnetic field in the vicinity of the heliopause (Röken et al. 2015) is extended from incompressible to compressible, yet predominantly subsonic flow, considering both isothermal and adiabatic equations of state. Exact expressions and suitable approximations for the density and the flow velocity are derived and discussed. In addition to the stationary induction equation, these expressions also satisfy the momentum balance equation along stream lines. The practical usefulness of the corresponding, still exact, analytical magnetic field solution is assessed by comparing it quantitatively to results from a fully self-consistent magnetohydrodynamic simulation of the interstellar magnetic field draping around the heliopause.