Magnetized Jets Driven by the Sun, the Structure of the Heliosphere Revisited: Consequences for Draping of BISM ahead of the HP and Time Variability of ENAs

Abstract:

Recently we proposed (Opher et al. 2015) that the structure of the heliosphere might be very different than we previously thought. The classic accepted view of the heliosphere is a quiescent, comet-like shape aligned in the direction of the Sun’s travel through the interstellar medium (ISM) extending for thousands of astronomical units. We have shown, based on magnetohydrodynamic (MHD) simulations, that the tension force of the twisted magnetic field of the Sun confines the solar wind plasma beyond the termination shock and drives jets to the north and south very much like astrophysical jets. These heliospheric jets are deflected into the tail region by the motion of the Sun through the ISM. As in some astrophysical jets the interstellar wind blows the two jets into the tail but is not strong enough to force the lobes into a single comet-like tail. Instead, the interstellar wind flows around the heliosphere and into the equatorial region between the two jets. We show that the heliospheric jets are turbulent (due to large-scale MHD instabilities and reconnection) and strongly mix the solar wind with the ISM. The resulting turbulence has important implications for particle acceleration in the heliosphere. The two-lobe structure is consistent with the energetic neutral atom (ENA) images of the heliotail from IBEX where two lobes are visible in the north and south and the suggestion from the Cassini ENAs that the heliosphere is “tailless.” The new structure of the heliosphere is supported by recent analytic work (Drake et al. 2015) that shows that even in high \beta heliosheath the magnetic field plays a crucial role in funneling the solar wind in two jets. Here we present these recent results and show that the heliospheric jets mediate the draping of the magnetic field and the conditions ahead of the heliopause. We show that reconnection between the interstellar and solar magnetic field both at the flanks of the jets and in between them twist the interstellar magnetic field in a small layer ahead of the HP in agreement with Voyager 1 observations (as seen in Opher & Drake 2013). We present results of the heliospheric jets for a weaker magnetic field, representative of the 2010-2012 period and what is expected to be seen in the ENA maps with solar cycle.