PROGRAM: S-8
Title:
TIME-VARYING HELIOSPHERIC SIZE DUE TO VARIATIONS IN SOLAR ACTIVITY2Center for Space Plasma and Aeronomic Research
3 Department of Space Science, University of Alabama in Huntsville, Huntsvulle, AL35899, USA
Abstract:
Using a three-dimensional MHD simulation, we examine the time-varying outer heliospheric structure and distance to the heliopause. Voyager 2 solar wind observations show that a global merged interaction region (GMIR) with a ram-pressure of the order of several nPa normalized at 1 AU enters the distant solar wind at an average rate of about one per year. This series of GMIRs adds an additional perturbative increase to the solar-wind ram-pressure in the inner heliosheath, and it also reduces the surrounding interstellar medium pressure acting on the heliopause, consequently our simulation results in the distance to the heliopause being ~14 AU larger when compared to the case when a series of GMIRs is not taken into account. In addition, OMNI data shows that the solar-wind ram-pressure near the Earth increases from ~1.3 nPa in year 2010 and before to 1.7-2.4 nPa after that until the present time. These variations in the overall ram-pressure of the solar-wind are also included in our simulation. The inclusion of the time variable solar-wind ram-pressure and the series of GMIRs allows us to illustrate how the realistic distance to the heliopause varies in response to both long- time and short-time variability in solar activity.