Tearing instability and periodic density perturbations in the slow solar wind

Abstract

In contrast with the fast solar wind, that originates in coronal holes, the source of the slow solar wind is still debated. Often intermittent and enriched with low FIP elements -- akin to what is observed in closed coronal loops -- the slow wind could form in bursty events nearby helmet streamers. Slow winds also exhibit density perturbations which have been shown to be periodic and could be associated with flux ropes ejected from the tip of helmet streamers, as shown recently by the WISPR white light imager onboard Parker Solar Probe (PSP). In this work, we propose that the main mechanism controlling the release of flux ropes is a flow-modified tearing mode at the heliospheric current sheet (HCS). We use MHD simulations of the solar wind and corona to reproduce realistic configurations and outflows surrounding the HCS. We find that this process is able to explain long ($\sim 10-20$h) and short ($\sim 1-2$h) timescales of density structures observed in the slow solar wind. This study also sheds new light on the structure, topology and composition of the slow solar wind, and could be, in the near future, compared with white light and in situ PSP observations.

8 pages, 5 figures, accepted for publication in ApJL

References in corpus (10)

• PLUTO: a Numerical Code for Computational Astrophysics
• Instability of current sheets and formation of plasmoid chains
• Turbulence in the sub-Alfvénic solar wind driven by reflection of low-frequency Alfvén waves
• Examining Periodic Solar Wind Density Structures Observed in the SECCHI Heliospheric Imagers
• The temporal and spatial scales of density structures released in the slow solar wind during solar activity maximum
• Relating streamer flows to density and magnetic structures at the Parker Solar Probe
• Observational evidence for the associated formation of blobs and raining inflows in the solar Corona
• Diamagnetic and Expansion Effects on the Observable Properties of the Slow Solar Wind in a Coronal Streamer
• In situ measurements of the variable slow solar wind near sector boundaries
• Global solar magnetic field organization in the outer corona: influence on the solar wind speed and mass flux over the cycle

Cited by in corpus (6)

• Flux ropes and dynamics of the heliospheric current sheet
• Validation of a wave heated 3D MHD coronal-wind model using Polarized Brightness and EUV observations
• Modeling Solar Wind Variations over an 11-yr Cycle with Alfvén Wave Dissipation: a Parameter Study
• A comparison study of extrapolation models and empirical relations in forecasting solar wind
• Influence of the heliospheric current sheet on the evolution of solar wind turbulence
• Current sheets, plasmoids and flux ropes in the heliosphere. Part II: Theoretical aspects