Accelerating and Supersonic Density Fluctuations in Coronal Hole Plumes: Signature of Nascent Solar Winds

Abstract

Slow magnetoacoustic waves in a static background provide a seismological tool to probe the solar atmosphere in the analytic frame. By analyzing the spatiotemporal variation of the electron number density of plume structure in coronal holes above the limb for a given temperature, we find that the density perturbations accelerate with supersonic speeds in the distance range from 1.02 to 1.23 solar radii. We interpret them as slow magnetoacoustic waves propagating at about the sound speed with accelerating subsonic flows. The average sonic height of the subsonic flows is calculated to be 1.27 solar radii. The mass flux of the subsonic flows is estimated to be 44.1$\%$ relative to the global solar wind. Hence, the subsonic flow is likely to be the nascent solar wind. In other words, the evolution of the nascent solar wind in plumes at the low corona is quantified for the first time from imaging observations. Based on the interpretation, propagating density perturbations present in plumes could be used as a seismological probe of the gradually accelerating solar wind.

Accepted for publication in ApJL, 11 pages, 5 figures

References in corpus (27)

• Solar Chemical Abundances Determined with a CO5BOLD 3D Model Atmosphere
• Prevalence of Small-scale Jets from the Networks of the Solar Transition Region and Chromosphere
• Generation of Solar Spicules and Subsequent Atmospheric Heating
• Hinode/EIS observations of propagating low-frequency slow magnetoacoustic waves in fan-like coronal loops
• Observation of High-speed Outflow on Plume-like Structures of the Quiet Sun and Coronal Holes with SDO/AIA
• Formation of quasi-periodic slow magnetoacoustic wave trains by the heating/cooling misbalance
• Frequency-dependent damping in propagating slow magneto-acoustic waves
• Propagating MHD waves in coronal holes
• STEREO Observations of Quasi-Periodically Driven High Velocity Outflows in Polar Plumes
• The Independency of Stellar Mass Loss Rates on stellar X-ray Luminosity and Activity Level based on Solar X-ray flux and Solar Wind Observations
• A coronal seismological study with streamer waves
• Propagating intensity disturbances in polar corona as seen from AIA/SDO
• First comparison of wave observations from CoMP and AIA/SDO
• Accelerating waves in polar coronal holes as seen by EIS and SUMER
• The polytropic index of solar coronal plasma in sunspot fan loops and its temperature dependence
• Streamer Wave Events Observed in Solar Cycle 23
• Spectroscopic Observations of Propagating Disturbances in a Polar Coronal Hole: Evidence of Slow Magneto-acoustic Waves
• Differential Emission Measure Plasma Diagnostics of a Long-Lived Coronal Hole
• Heating of an erupting prominence associated with a solar coronal mass ejection on 2012 January 27
• 2D solar wind speeds from 6 to 26 solar radii in solar cycle 24 by using Fourier filtering
• Collisional and Radiative Processes in Optically Thin Plasmas
• Properties of Streamer Wave Events Observed During the STEREO Era
• SITES: Solar Iterative Temperature Emission Solver for differential emission measure inversion of EUV observations
• Non-equilibrium ionization effects on solar EUV and X-ray imaging observations
• Coronal Bright Points as possible sources of density variations in the Solar Corona
• Non-equilibrium Ionization Effects on Extreme-Ultraviolet Emissions Modulated by Standing Sausage Modes in Coronal Loops
• Seismological determination of the Alfvén speed and plasma-beta in solar photospheric bright points

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