Abstract
Abstract. Solar wind ram pressure variations occuring within the solar activity cycle are communicated to the outer heliosphere as complicated time-variabilities, but repeating its typical form with the activity period of about 11 years. At outer heliospheric regions, the main surviving solar cycle feature is a periodic variation of the solar wind dynamical pressure or momentum flow, as clearly recognized by observations of the VOYAGER-1/2 space probes. This long-periodic variation of the solar wind dynamical pressure is modeled here through application of appropriately time-dependent inner boundary conditions within our multifluid code to describe the solar wind – interstellar medium interaction. As we can show, it takes several solar cycles until the heliospheric structures adapt to an average location about which they carry out a periodic breathing, however, lagged in phase with respect to the solar cycle. The dynamically active heliosphere behaves differently from a static heliosphere and especially shows a historic hysteresis in the sense that the shock structures move out to larger distances than explained by the average ram pressure. Obviously, additional energies are pumped into the heliosheath by means of density and pressure waves which are excited. These waves travel outwards through the interface from the termination shock towards the bow shock. Depending on longitude, the heliospheric sheath region memorizes 2–3 (upwind) and up to 6–7 (downwind) preceding solar activity cycles, i.e. the cycle-induced waves need corresponding travel times for the passage over the heliosheath. Within our multifluid code we also adequately describe the solar cycle variations in the energy distributions of anomalous and galactic cosmic rays, respectively. According to these results the distribution of these high energetic species cannot be correctly described on the basis of the actually prevailing solar wind conditions.Key words. Interplanetary physics (heliopause and solar wind termination; general or miscellaneous) – Space plasma physics (experimental and mathematical techniques)
Highlights
Solar wind ram pressure variations occuring within the solar activity cycle are communicated to the outer heliosphere as complicated time-variabilities, but repeating its typical form with the activity period of about 11 years
The inclusion of pick-up ions (PUIs), anomalous cosmic rays (ACRs)- and galactic cosmic rays (GCRs)-fluids in a physical sense opens up new reaction modes for the whole interaction system, if timedependent inner boundary conditions modeling typical solar cycle variations are installed
In the case of model 1, we used a similar parameter set, as discussed in Table 1, but without any interaction of the PUIs, ACRs, and GCRs as input for the sinusoidal solar cycle model
Summary
Since Parker (1963) published the first description of the heliospheric interface configuration, it was already obvious that the locations of the solar wind termination shock and the heliopause would vary under different inner heliospheric pressure conditions. Fahr: Breathing of heliospheric structures triggered by the solar-cycle activity quately described if the whole interaction system is consistently estimated, including all involved time-dependent processes, especially, for example, the back reactions from the heliopause and the bow shock In this sense Steinolfson (1994) and Karmesin et al (1995) have run the first two-dimensional, time-dependent interaction codes to study solar cycle effects and could show that the resulting migrations of the shock location in their timedependent studies turn out to be much more moderate compared to migrations achieved if the shock could instantly react to the actual inner solar wind conditions. These latter components are pick-up ions (PUIs), anomalous cosmic rays (ACRs) and galactic cosmic rays (GCRs) (see Fahr et al, 2000; Scherer et al, 2002)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
