The Spectroscopic Footprint of the Fast Solar Wind

Abstract

We analyze a large, complex equatorial coronal hole (ECH) and its immediate surroundings with a focus on the roots of the fast solar wind. We start by demonstrating that our ECH is indeed a source of the fast solar wind at 1AU by examining in situ plasma measurements in conjunction with recently developed measures of magnetic conditions of the photosphere, inner heliosphere and the mapping of the solar wind source region. We focus the bulk of our analysis on interpreting the thermal and spatial dependence of the non-thermal line widths in the ECH as measured by SOHO/SUMER by placing the measurements in context with recent studies of ubiquitous Alfven waves in the solar atmosphere and line profile asymmetries (indicative of episodic heating and mass loading of the coronal plasma) that originate in the strong, unipolar magnetic flux concentrations that comprise the supergranular network. The results presented in this paper are consistent with a picture where a significant portion of the energy responsible for the transport of heated mass into the fast solar wind is provided by episodically occurring small-scale events (likely driven by magnetic reconnection) in the upper chromosphere and transition region of the strong magnetic flux regions that comprise the supergranular network.

25 pages, accepted to appear in the Astrophysical Journal. Supporting movies can be found in http://download.hao.ucar.edu/pub/mscott/papers/ECH/

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• Observation and Modeling of Solar Jets
• Deciphering Solar Magnetic Activity I: On The Relationship Between The Sunspot Cycle And The Evolution Of Small Magnetic Features
• Observation of High-speed Outflow on Plume-like Structures of the Quiet Sun and Coronal Holes with SDO/AIA
• SDO Observations of Magnetic Reconnection at Coronal Hole Boundaries
• Spectroscopic Observations of Propagating Disturbances in a Polar Coronal Hole: Evidence of Slow Magneto-acoustic Waves
• Observing Evolution in the Supergranular Length Scale During Periods of Low Solar Activity
• Solar Cycle Variations in the Elemental Abundance of Helium and Fractionation of Iron in the Fast Solar Wind - Indicators of an Evolving Energetic Release of Mass from the Lower Solar Atmosphere
• Is magnetic reconnection the cause of supersonic upflows in granular cells ?
• Recent Observations of Plasma and Alfvenic Wave Energy Injection at the Base of the Fast Solar Wind
• IRIS observations of the low-atmosphere counterparts of active region outflows
• Revisiting the relation between nonthermal line widths and transverse MHD wave amplitudes
• Tracking Back the Solar Wind to its Photospheric Footpoints from Wind Observations -- A Statistical Study
• Investigating coronal wave energy estimates using synthetic non-thermal line widths