Global Field Orientation Across the Heliopause As a Result of Regions of Reconnection

Monday, 15 December 2014
Merav Opher1, James Frederick Drake2, Bertalan Zieger1 and Tamas I Gombosi3, (1)Boston University, Boston, MA, United States, (2)University of Maryland College Park, College Park, MD, United States, (3)Univ of Michigan, Ann Arbor, MI, United States
Based on the difference between the orientation of the interstellar and the solar magnetic fields, there was an expectation by the community that the magnetic field direction will rotate dramatically across the heliopause (HP). Based on the radio emission, the Voyager team concluded that Voyager 1 (V1) crossed into interstellar space at the end of August 2013. The question is then why there was no significant rotation in the direction of the magnetic field across the HP. Our recent global simulations (Opher & Drake 2013) revealed that strong rotations in the direction of the magnetic field at the HP at the location of V1 (and Voyager 2) are not expected. We showed that for a wide range of orientations of BISM the angle δ = a sin(BN /B) is small (around 10◦–20◦) ahead of V1 as seen in the observations. Only after some significant distance outside the HP (~ 20AU) is the direction of the interstellar field distinguishably different from that of the Parker spiral. The field outside the HP slowly rotates with a small change (around 2 degree/AU); as seen by observations (Burlaga & Ness 2014). Here we show that the reason for the twist of the BISM to the solar direction is due to favorable locations for global reconnection on the HP. We explore of the effect of the location of the reconnection on the draping of the magnetic field and flows just outside the HP. We further explore the consequences for what Voyager 2 will encounter.