The drivers of active region outflows into the slow solar wind

Abstract

Plasma outflows from the edges of active regions have been suggested as a possible source of the slow solar wind. Spectroscopic measurements show that these outflows have an enhanced elemental composition, which is a distinct signature of the slow wind. Current spectroscopic observations, however, do not have sufficient spatial resolution to distinguish what structures are being measured or to determine the driver of the outflows. The High-resolution Coronal Imager (Hi-C) flew on a sounding rocket in May, 2018, and observed areas of active region outflow at the highest spatial resolution ever achieved (250 km). Here we use the Hi-C data to disentangle the outflow composition signatures observed with the Hinode satellite during the flight. We show that there are two components to the outflow emission: a substantial contribution from expanded plasma that appears to have been expelled from closed loops in the active region core, and a second contribution from dynamic activity in active region plage, with a composition signature that reflects solar photospheric abundances. The two competing drivers of the outflows may explain the variable composition of the slow solar wind.

To be published in The Astrophysical Journal. Figures 1, 2, 3 and 12 are reduced resolution to meet size requirements. The original figures will appear in the published version

References in corpus (10)

• Observing the Roots of Solar Coronal Heating - in the Chromosphere
• High Resolution Observations and Modeling of Dynamic Fibrils
• Flows and Non-thermal Velocities in Solar Active Regions Observed with the Extreme-ultraviolet Imaging Spectrometer on Hinode: A Tracer of Active Region Sources of Heliospheric Magnetic Fields?
• Observations of Active Region Loops with the EUV Imaging Spectrometer on Hinode
• Modelling of EIS spectrum drift from instrumental temperatures
• Hinode/Extreme-Ultraviolet Imaging Spectrometer Observations of the Temperature Structure of the Quiet Corona
• FIP Bias Evolution in a Decaying Active Region
• Flows and Motions in Moss in the Core of a Flaring Active Region: Evidence for Steady Heating
• High-resolution observations of active region moss and its dynamics
• Comprehensive Determination of the Hinode/EIS Roll Angle

Cited by in corpus (18)

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• IRIS observations of the low-atmosphere counterparts of active region outflows
• A comparison of the active region upflow and core properties using simultaneous spectroscopic observations from IRIS and Hinode
• Plasma composition measurements in an active region from Solar Orbiter/SPICE and Hinode/EIS
• Inconspicuous Solar Polar Coronal X-ray Jets as the Source of Conspicuous Hinode/EUV Imaging Spectrometer (EIS) Doppler Outflows
• Near subsonic solar wind outflow from an active region
• The Formation and Lifetime of Outflows in a Solar Active Region
• Widespread Occurrence of High-Velocity Upflows in Solar Active Regions
• Dropouts of Fully Stripped Ions in the Solar Wind: A Diagnostic for Wave Heating versus Reconnection
• Dynamics in the transition region beneath active region upflows viewed by IRIS
• Signature and escape of highly fractionated plasma in an active region
• Population of Bright Plume Threads in Solar Polar Coronal Holes
• Pre-flare and active region plasma flows and structure seen by the short wavelength camera on SOLAR-C/EUVST
• Active region upflows in various coronal structures and their coupling to the lower atmosphere
• Testing the Alfvén-wave model of the solar wind with interplanetary scintillation