Instabilities and Magnetic Reconnection near the Heliopause

Abstract:

Recent observations from the Voyager 1 spacecraft show that it is sampling the local interstellar medium (LISM). This is quite surprising because standard steady-state and time-dependent models of the solar wind (SW) interaction with the LISM cannot give the heliopause position at about 120 AU without unrealistic assumptions about the LISM properties. This includes such models that assume a strong redistribution of the ion energy to the tails in the pickup ion distribution function. We investigate the heliopause (HP) stability with increased spatial resolution to reveal the details of the coupling between the heliospheric and interstellar magnetic fields (HMF and ISMF) at the heliospheric interface. In particular, this resolution makes it possible to perform a detailed comparison with Voyager observations. We also analyze magnetic field simulation results to identify the areas of possible magnetic reconnection between the HMF and ISMF lines. The Rayleigh-Taylor instability is considerably suppressed near the HP nose by the heliospheric magnetic field in steady-state models, but reveals itself in the presence of solar cycle effects. We argue that Voyager 1 may have penetrated into the LISM through such instability region. We also compare numerical simulations with the LISM properties taken from either Ulysses or IBEX observations.