Comparing various multi-component global heliosphere models

¹ Department of Physics and Astronomy, Dartmouth College, Hanover NH 03755, USA e-mail: hans.mueller@dartmouth.edu
² Institute of Geophysics and Planetary Physics, University of California, Riverside CA 92521, USA e-mail: vflorins@ucr.edu; jacobh@ucr.edu
³ Lomonosow Moscow State University, Department of Mechanics and Mathematics & Institute of Mechanics, Moscow 119899, Russia e-mail: izmod@ipmnet.ru
⁴ Institute for Problems in Mechanics, Russian Academy of Sciences, Moscow 119526, Russia
⁵ Ruhr-Universität Bochum, Institut für Theoretische Physik IV: Weltraum- und Astrophysik, 44780 Bochum, Germany e-mail: kls@tp4.rub.de
⁶ Argelander Institute for Astronomy, Dept. of Astrophysics, University of Bonn, Auf dem Hügel 71, 53121 Bonn, Germany e-mail: hfahr@astro.uni-bonn.de

Received: 19 September 2007
Accepted: 31 March 2008

Abstract

Context. Modeling of the global heliosphere seeks to investigate the interaction of the solar wind with the partially ionized local interstellar medium. Models that treat neutral hydrogen self-consistently and in great detail, together with the plasma, but that neglect magnetic fields, constitute a sub-category within global heliospheric models.

Aims. There are several different modeling strategies used for this sub-category in the literature. Differences and commonalities in the modeling results from different strategies are pointed out.

Methods. Plasma-only models and fully self-consistent models from four research groups, for which the neutral species is modeled with either one, three, or four fluids, or else kinetically, are run with the same boundary parameters and equations. They are compared to each other with respect to the locations of key heliospheric boundary locations and with respect to the neutral hydrogen content throughout the heliosphere.

Results. In many respects, the models' predictions are similar. In particular, the locations of the termination shock agree to within 7% in the nose direction and to within 14% in the downwind direction. The nose locations of the heliopause agree to within 5%. The filtration of neutral hydrogen from the interstellar medium into the inner heliosphere, however, is model dependent, as are other neutral results including the hydrogen wall. These differences are closely linked to the strength of the interstellar bow shock. The comparison also underlines that it is critical to include neutral hydrogen into global heliospheric models.