Magnetic Connectivity in the Corona as a Source of Structure in the Solar Wind

Abstract

Five decades of satellite data confirm that the solar wind contains many boundaries separating flow with distinct magnetic and plasma properties. Some speculate the boundaries in the solar wind found at Earth originate at the solar surface and are carried along with the expanding solar wind as fossil structures to 1 AU. This begs the question, is it the physics and magnetic structure above the photosphere that creates well‐defined boundaries between different magnetic flux regions at 1 AU in the solar wind? Magnetic boundaries in the corona exist all the time as topological features of null points in the field. These topological magnetic boundaries seem to be likely locations for plasma boundaries. It can be expected that these boundaries are typical locations where field line‐integrated quantities, such as field‐aligned current, experience large and abrupt changes. We perform three‐dimensional resistive magnetohydrodynamic simulations of the solar corona driven by photospheric foot point motions. We find that large and abrupt changes occur for field line‐integrated quantities across a magnetic topological boundary and the cause for these changes is the discontinuous mapping for magnetic field lines and thus for Alfvén waves across these boundaries. It is also demonstrated via in situ properties that thin layers of field‐aligned and perpendicular currents are frequently located at or close to topological boundaries.

Responses and Periodic Variations of Cosmic Ray Intensity and Solar Wind Speed to Sunspot Numbers

“…observed were mostly around descending and ascending phases of the solar cycles. Largely, the uneven phase interactions at different periodicities could be ascribed to the pattern of configuration in the coronal hole and the solar wind outflow from different sources due to the solar magnetic structures [44,45]. e cross-correlation analysis agrees with previous studies.…”

The Compression of the Heliospheric Magnetic Structure by Interplanetary Shocks: Is the Structure at 1AU a Manifestation of Solar-Wind Turbulence or Is It Fossil Structure From the Sun?

“…This finding agrees with an earlier analysis (Borovsky and Denton, 2016) wherein the anisotropy of solar wind current sheets in the compression regions of corotating interaction regions and in the rarefaction regions of the trailing edges of high-speed streams: that analysis found no indication of current sheets isotropizing in the 10's of hours after the solar-wind plasma is compressed or rarefacted. This may support the idea that the heliospheric magnetic structure at 1 AU and its current sheets are largely fossil structure from the solar corona (e.g., Michel, 1967;Borovsky, 2008a;Huang et al, 2014;Burkholder et al, 2019;Eselevich, 2019) or remnants of a near-Sun turbulence that ceased to be active (e.g., Dobrowolny et al, 1980;Telloni et al, 2016).…”

Some Properties of the Solar Wind Turbulence at 1 AU Statistically Examined in the Different Types of Solar Wind Plasma

“…The Parker spiral plasmas (coronal‐hole‐origin plasma and streamer‐belt‐origin plasma) tend to be more Alfvénic, with correlations between the vector velocity fluctuations and the vector magnetic‐field fluctuations. Alfvénic fluctuations in the solar wind seem to be a sign of an open‐flux process, perhaps reconnection events between open field lines and low‐lying closed loops (Burkholder et al, ; He et al, ; Pariat et al, ; Shibata et al, ; Torok et al, ; Yang et al, ) or perhaps firehose instabilities driven by plasma jetting in open flux tubes (Farahani et al, ; Mann et al, ; Zhelyazkov, ).…”