Articles | Volume 33, issue 1
Ann. Geophys., 33, 47–53, 2015

Special issue: Observation, analysis and modelling of solar and heliospheric...

Ann. Geophys., 33, 47–53, 2015

Regular paper 12 Jan 2015

Regular paper | 12 Jan 2015

Three-dimensional multi-fluid model of a coronal streamer belt with a tilted magnetic dipole

L. Ofman1,2,3, E. Provornikova1,2, L. Abbo4, and S. Giordano4 L. Ofman et al.
  • 1Department of Physics, Catholic University of America, Washington, DC 20064, USA
  • 2NASA Goddard Space Flight Center, Code 671, Greenbelt, MD 20771, USA
  • 3Visiting Associate Professor, Department of Geosciences, Tel Aviv University, Tel Aviv, Israel
  • 4INAF-Astrophysical Observatory of Torino, via Osservatorio 20, 10025 Pino Torinese, Italy

Abstract. Observations of streamers in extreme ultraviolet (EUV) emission with SOHO/UVCS show dramatic differences in line profiles and latitudinal variations in heavy ion emission compared to hydrogen Ly-α emission. In order to use ion emission observations of streamers as the diagnostics of the slow solar wind properties, an adequate model of a streamer including heavy ions is required. We extended a previous 2.5-D multi-species magnetohydrodynamics (MHD) model of a coronal streamer to 3-D spherical geometry, and in the first approach we consider a tilted dipole configuration of the solar magnetic field. The aim of the present study is to test the 3-D results by comparing to previous 2.5-D model result for a 3-D case with moderate departure from azimuthal symmetry. The model includes O5+ ions with preferential empirical heating and allows for calculation of their density, velocity and temperature in coronal streamers. We present the first results of our 3-D multi-fluid model showing the parameters of protons, electrons and heavy ions (O5+) at the steady-state solar corona with a tilted steamer belt. We find that the 3-D results are in qualitative agreement with our previous 2.5-D model, and show longitudinal variation in the variables in accordance with the tilted streamer belt structure. Properties of heavy coronal ions obtained from the 3-D model together with EUV spectroscopic observations of streamers will help understanding the 3-D structures of streamers reducing line-of-sight integration ambiguities and identifying the sources of the slow solar wind in the lower corona. This leads to improved understanding of the physics of the slow solar wind.

Short summary
First results from the three-fluid 3D model of the solar corona are reported. The model extends previous 2.5D three-fluid studies, and includes electron, protons, and oxygen ions (O5+) as coupled fluids in a tilted dipole solar magnetic field configuration. The model demonstrates the variation in abundances of the oxygen ions relative to protons in a coronal streamer belt, thus identifying the sources of the slow solar wind and helping in the interpretation of past spectroscopic observations.