Active Region Moss: Basic physical parameters and their temporal variation

Abstract

We present a study of the physical plasma parameters such as electron temperature, electron density, column depth and filling factors in the moss regions and their variability over a short (an hour) and a long period (5 consecutive days) of time. Primarily, we have analyzed the spectroscopic observations recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) aboard Hinode. In addition we have used supplementary observations taken from TRACE and the X-Ray Telescope (XRT). We find that the moss emission is strongest in the Fe xii and Fe xiii lines. Based on analyses using line ratios and emission measure we found that the moss region has a characteristic temperature of log T = 6.2. The electron densities measured at different locations in the moss regions using Fe xii ratios are about 1-3\times1010 cm(-3) and about 2-4\times10^9 cm^(-3) using Fe xiii and Fe xiv. The electron density substantially increases (by a factor of about 3-4 or even more in some cases) when a background subtraction was performed. The density and temperature show very small variation over time. The filling factor of the moss plasma can vary between 0.1-1 and the path length along which the emission originates is from a few 100 to a few 1000 kms long. By combining the observations recorded by TRACE, EIS and XRT, we find that the moss regions correspond to the foot-points of both hot and warm loops.

10 pages, 12 figures, Accepted for publication in Astronomy and Astrophysics

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• High precision density measurements in the solar corona: I. Analysis methods and results for Fe XII and Fe XIII
• On active region loops: Hinode/EIS observations
• Observations of Active Region Loops with the EUV Imaging Spectrometer on Hinode
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Cited by in corpus (30)

• Solar UV and X-Ray Spectral Diagnostics
• Observing coronal nanoflares in active region moss
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• Emission Measure Distribution and Heating of Two Active Region Cores
• Diagnosing the time-dependence of active region core heating from the emission measure: I. Low-frequency nanoflares
• Velocity measurements for a solar active region fan loop from Hinode/EIS observations
• Temperature distribution of a non-flaring active region from simultaneous Hinode XRT and EIS observations
• Investigating the response of loop plasma to nanoflare heating using RADYN simulations
• A Coronal Hole Jet Observed with Hinode and the Solar Dynamics Observatory
• IRIS observations of short-term variability in moss associated with transient hot coronal loops
• High spatial resolution FeXII observations of solar active region
• Evidence of Impulsive Heating in Active Region Core Loops
• The Evolution of the EM Distribution in the Core of an Active Region
• Spectroscopic Observations of a Coronal Loop: Basic Physical Plasma Parameters Along the Full Loop Length
• Asymmetries in Coronal Spectral lines and Emission Measure Distribution
• Observations of Plasma Upflow in a Warm Loop with Hinode/EIS
• EUV Spectra of Solar Flares from the EUV Spectroheliograph SPIRIT aboard CORONAS-F satellite
• Active Region Moss: Doppler Shifts from Hinode/EIS Observations
• Fan Loops Observed by IRIS, EIS and AIA
• High-resolution observations of active region moss and its dynamics
• Emission Measure Distribution for Diffuse Regions in Solar Active Regions
• Energetics of Hi-C EUV Brightenings
• Coronal Abundances in an Active Region: Evolution and Underlying Chromospheric and Transition Region Properties
• Quantifying the Influence of Key Physical Processes on the Formation of Emission Lines Observed by IRIS: I. Non-Equilibrium Ionization and Density-Dependent Rates
• How transverse MHD wave-driven turbulence influences the density filling factor in the solar corona?
• Formation and Dynamics of Transequatorial Loops
• High Resolution Observations of the Low Atmospheric Response to Small Coronal Heating Events in an Active Region Core
• The Transition Region of Solar Flare Loops
• Machine Learning-based Separation of the He I 10830Å Chromospheric Signal: Quantitative Analysis of Chromosphere-Corona Intensity in the Quiet Sun
• Plasma Diagnostics From Active Region and Quiet Sun Spectra Observed by Hinode/EIS: Quantifying the Departures from a Maxwellian Distribution