Stream structures in the outer heliosphere

Nineteen magnetic clouds are identified in the years from 1978 through 1982 and studied by the superimposed epoch method. The magnetic fluctuations, density, and temperature are enhanced ahead of the clouds preceded by shocks. Strong magnetic field intensities and low proton temperatures are observed in the clouds. A relatively large (2.5%) decrease in cosmic ray intensity is caused by the turbulent sheath behind an interplanetary shock ahead of a magnetic cloud. Only a small (0.5%) decrease in intensity is associated with the magnetic cloud itself. Magnetic clouds can produce geomagnetic activity with a decrease in the Dst index of the order of 100 gammas. The magnitude of the change in Dst index for the case when southward fields arrive first is comparable to that for the case of northward fields first, and the phase is such that geomagnetic activity is associated with the southward fields

Radiative transfer for parallel streams of radiating gases

Radiative and convective heat transfer between two parallel streams of absorbing and emitting radiating gase

Magnetosphere of Mercury

A model magnetosphere of Mercury using Mariner 10 data is presented. Diagrams of the bow shock wave and magnetopause are shown. The analysis of Mariner 10 data indicates that the magnetic field of the planet is intrinsic. The magnetic tail and secondary magnetic fields, and the influence of the solar wind are also discussed

On mass transfer between two parallel streams

Convective and diffusive mass transfer between two parallel gas stream

Conversion of magnetic field energy into kinetic energy in the solar wind

The outflow of the solar magnetic field energy (the radial component of the Poynting vector) per steradian is inversely proportional to the solar wind velocity. It is a decreasing function of the heliocentric distance. When the magnetic field effect is included in the one-fluid model of the solar wind, the transformation of magnetic field energy into kinetic energy during the expansion process increases the solar wind velocity at 1 AU by 17 percent

Interaction of minor ions with fast and slow shocks

The coronal slow shock was predicted to exist embedded in large coronal holes at 4 to 10 solar radii. A three-fluid model was used to study the jumps in minor ions propertes across the coronal slow shock. The jump conditions were formulated in the de Hoffmann-Teller frame of reference. The Rankine-Hugoniot solution determines the MHD flow and the magnetic field across the shocks. For each minor ion species, the fluid equations for the conservation of mass, momentum, and energy can be solved to determine the velocity and the temperature of the ions across the shock. A simularity solution was also obtained for heavy ions. The results show that on the downstream side of the coronal slow shock the ion temperatures are nearly proportional to the ion masses for He, O, Si, and Fe in agreement with observed ion temperatures in the inner solar wind. This indicates that the possibly existing coronal slow shock can be responsible for the observed heating of minor ions in the solar wind

An inviscid model of the solar wind

Inviscid, thermal conductive, spherically symmetric solar wind model - model solution by integration of mass, momentum, and energy conservation equation

Evolution of the solar wind structure in the outer heliosphere

Shocks and interaction regions play very important roles in the evolution of large-scale solar wind structure in the outer heliosphere. This study is based on (1) plasma and magnetic field data observed from Voyager and Pioneer spacecraft, and (2) a quantitative magnetohydrodynamic simulation model. Interaction regions bounded by a forward and a reverse shock begin to form near 1 AU at the leading edges of a large-scale stream. The total pressure in the region is greater than the ambient pressure by a factor of ten or more. Large jumps in pressure remain as a prominant feature of the interplanetary structure even as the jumps in flow speed become less visible in the outer heliosphere. The propagation of the forward and reverse shocks widens the dimension of an interaction region. As a result, two interaction regions belonging to neighboring streams coalesce to form a merged interaction region (MIR). Collision and merging of shocks take place during the coalescence process. Two MIRs can themselves merge again at greater heliocentric distances. Simulation results agree well with spacecraft observations, and they explain major restructuring of the solar wind in the outer heliosphere

Modelling the magnetosphere of Mercury

A model magnetosphere for Mercury is presented using an upstream image-dipole and nightside 2-dimensional tail current sheet method. The tail field is represented by an analytical formulation. Magnetic field data from the Mercury 1 encounter by Mariner 10 in March 1974 are used to determine quantitative parameters of the model magnetosphere, using the method of least squares. The magnetopause crossing points directly observed are used to determine the size of the magnetosphere, and the solar wind conditions are used to determine the magnetospheric field at the stagnation point. The model produces a magnetosphere-like region with planetary field lines that are confined in nearly circular cross-sections transverse to the sun-planet line. Results are used to show geometry, field line configuration, and contours of constant field intensity inside the magnetosphere

Coalescence of two pressure waves associated with stream interactions

An MHD unsteady 1-D model is used to simulate the interaction and coalescence of two pressure waves in the outer heliosphere. Each of the two pressure waves was a compression region bounded by a shock pair. Computer simulation using Voyager data as input demonstrates the interaction and coalescence process involving one pressure wave associated with a fast stream and the other pressure wave without a fast stream. The process produced a significant change in the magnetic field and plasma signatures. The propagation of the forward and reverse shocks first widened the radial dimension of the shock compression region with increasing heliocentric distances. The shocks belonging to two neighboring compression regions eventually collided and two compression regions began to overlap with each other. This type of interaction is a dominant dynamical process in the outer heliosphere, and significantly and irreversible alters the structure of the medium