The einstein observatory medium sensitivity survey

Results are presented from an X-ray survey of 50 square degrees of the high galactic latitude sky at sensitivities in the range 7·10^–14 – 5·10^–12 erg/cm² sec (0·3–3·5 keV) carried out with the Imaging Proportional Counter (IPC) aboard the Einstein Observatory. The extragalactic sample consists of 48 sources which have been used to determine the number flux relation. The content of the sample is analyzed in terms of types of sources and is found to be significantly different from the content of similar samples selected at higher fluxes.     

Victor A. Brumberg and Eugene V. Brumberg,Celestial Dynamics at High Eccentricities

Space Science Reviews -     

Interplanetary shock waves: Recent developments

Direct and indirect observations of interplanetary shock waves have been extended to the study of (i) the shock structure itself; (ii) the disturbed solar wind in its wake; (iii) additional discontinuities such as reverse shocks and pistons; and (iv) the shock's kinematic behavior. The last item — the trajectory — has benefited by the procedure (suggested by Pintér) of matching type II radio drift-inferred velocities with indirectly-inferred initial velocities found from at least two successive measurements in space. The significance of making type II observations at hectometric and kilometric wavelengths (as made, for example, by Slysh and Malitson, Feinberg and Stone) cannot be over-emphasized due to this technique's ability to make unambiguous solar terrestrial relationships. More direct and physically-meaningful observations, however, are still dependent uponin situ plasma and magnetic field measurements. Additional emphasis is presently being placed on numerical modeling of shock-induced disturbances in the solar wind as generated by both flares and stream-stream interactions. The former mechanism is emphasized in this review with several recommendations for further research: (a) further numerical modeling for shocks, starting when they are born within relatively low-Alfvén speed coronal regions; (b) expanded synoptic studies by spacecraft at various heliocentric longitudes, radii, and (eventually) latitudes with coordinated diagnostics; and (c) extended patrol of natural probes, such as comets, augmented with theoretical studies of possible shock-induced mechanical and chemical effects.     

Can space exploration survive the end of the Cold War?

The first, heroic age of space exploration was drived by national rivalry between the USA and USSR. There have indeed been recent achievements, but as the Cold War ends the superpowers are turning their attention to domestic issues and the prospect looms of a prolonged hiatus in space exploration. The only way forward is through international cooperation, but this will never happen without a serious investment of political will. A well-planned, long-term strategy for the exploration of Mars could provide the necessary focus.     

Saturn's Rings: pre-Cassini Status and Mission Goals

Theoretical and observational progress in studies of Saturn's ring system since the mid-1980s is reviewed, focussing on advances in configuration and dynamics, composition and size distribution, dust and meteoroids, interactions of the rings with the planet and the magnetosphere, and relationships between the rings and various satellites. The Cassini instrument suite of greatest relevance to ring studies is also summarized, emphasizing how the individual instruments might work together to solve outstanding problems. The Cassini tour is described from the standpoint of ring studies, and major ring science goals are summarized. This revised version was published online in August 2006 with corrections to the Cover Date.     

Three-dimensional global simulation of multiple ICMEs’ interaction and propagation from the Sun to the heliosphere following the 25–28 October 2003 solar events

This study performs simulations of interplanetary coronal mass ejection (ICME) propagation in a realistic three-dimensional (3D) solar wind structure from the Sun to the Earth by using the newly developed hybrid code, HAFv.2+3DMHD. This model combines two simulation codes, Hakamada–Akasofu–Fry code version 2 (HAFv.2) and a fully 3D, time-dependent MHD simulation code. The solar wind structure is simulated out to 0.08 AU (18 Rs) from source surface maps using the HAFv.2 code. The outputs at 0.08 AU are then used to provide inputs for the lower boundary, at that location, of the 3D MHD code to calculate solar wind and its evolution to 1 AU and beyond. A dynamic disturbance, mimicking a particular flare’s energy output, is delivered to this non-uniform structure to model the evolution and interplanetary propagation of ICMEs (including their shocks). We then show the interaction between two ICMEs and the dynamic process during the overtaking of one shock by the other. The results show that both CMEs and heliosphere current sheet/plasma sheet were deformed by interacting with each other.     

R. von Steiger,R. Lallement,and M.S. Lee (eds.). The Heliosphere in the Local Interstellar Medium

Space Science Reviews -     

A transient MHD model applicable for the source of solar cosmic ray acceleration

A two-dimensional, time-dependent magnetohydrodynamic (MHD) model is used to describe the possible mechanisms for the source of solar cosmic ray acceleration following a solar flare. The hypothesis is based on the propagation of fast mode MHD shocks following a sudden release of energy. This model has already been used with some success for simulation of some major features of type II shocks and white light coronal transients. In this presentation, we have studied the effects of initial magnetic topology and strength on the formation of MHD shocks. We consider the plasma beta (thermal pressure/magnetic pressure) as a measure of the $\text{initial}$, relative strength of the field. During dynamic mass motion, the Alfvén Mach number is the more appropriate measure of the magnetic field's ability to control the outward motion. We suggest that this model (computed self-consistently) provides the shock wave and the disturbed mass motion behind it as likely sources for solar cosmic ray acceleration.     

Bengt Hultqvist and Marit Oieroset (eds.), Transport Across the Boundaries of the Magnetosphere

Space Science Reviews -