Magnetic Reconnection Science in the Outer Heliosphere

Abstract

Helio2050 White Paper: Magnetic Reconnection Science in the Outer Heliosphere Authors: Stefan Eriksson1, Alfred Mallet2, Marc Swisdak3, Merav Opher4, Elena Provornikova5, Stuart Bale2, Mihir Desai6, Alexandra Alexandrova7 Affiliations: (1) Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, USA; (2) University of California Berkeley, USA; (3) University of Maryland, USA; (4) Boston University, USA; (5) The Johns Hopkins University Applied Physics Laboratory, USA; (6) Southwest Research Institute, USA; (7) Laboratoire de Physique des Plasmas, France What We Know: There is plentiful evidence of Alfvénic reconnection exhausts across inner heliosphere current sheets of many spatial scales. Most events are observed in time scales ranging from the highest plasma instrument cadence available (>3 s) to several minutes with a few known examples also reported at the hour time scale of Heliospheric Current Sheet (HCS) crossings [e.g., Gosling et al., 2005a; 2005b; 2006a; 2006b; 2006c; 2007]. These exhausts are the “smoking guns” of magnetic reconnection X‐lines that change the magnetic topology and allow the ions and electrons to cross a current sheet (CS) boundary along the magnetic field. Magnetic reconnection is known to be a key mechanism that ultimately converts magnetic field energy into bulk flow energy, particle acceleration and plasma heating [e.g., Drake et al., 2009; Phan et al., 2014]. It may also enable the growth of large‐scale magnetic field structures known as magnetic islands when several X‐lines are present at the same CS. Inner heliosphere reconnection exhausts are mostly observed in a low ion beta (βi<1) regime in agreement with the background βi‐ distribution (Figure 1), where βi is the ratio of proton plasma pressure to magnetic field pressure.