Hinode EIS line widths in the quiet corona up to 1.5 Rsun
arXiv:1905.09783 · doi:10.1051/0004-6361/201834625
Abstract
We present an analysis of several Hinode EIS observations of coronal line widths in the quiet Sun, up to 1.5 Rsun radial distances. No significant variations are found, which indicates no damping of Alfvén waves in the quiescent corona. However, the uncertainties in estimating the instrumental width mean that a firm conclusion cannot be reached. We present a discussion of various EIS instrumental issues and suggest that the strongest lines, from Fe XII at 193.5 and 195.1 A, have anomalous instrumental widths. We show how line widths in EIS are uncertain when the signal is low, and that the instrumental variation along the slit is also uncertain. We also found an anomalous decrease (up to 40%) in the intensities of these lines in many off-limb and active region observations, and suggest that this is due to opacity effects. We find that the most reliable measurements are obtained from the weaker lines.
Submitted to A&A, under revision - comments welcomed
References in corpus (6)
- Solar UV and X-Ray Spectral Diagnostics
- High precision density measurements in the solar corona: I. Analysis methods and results for Fe XII and Fe XIII
- Solar coronal lines in the visible and infrared. A rough guide
- Evidence for Wave Heating of the Quiet Sun Corona
- Predicting the COSIE-C Signal from the Outer Corona up to 3 Solar Radii
- Spectroscopic evidence of Alfvén wave damping in the off-limb solar corona
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- Fe XII and Fe XIII Line Widths in the Polar Off-limb Solar Corona up to 1.5 Rsun
- Estimating Ion Temperatures at the Polar Coronal Hole Boundary
- Plasma Diagnostics From Active Region and Quiet Sun Spectra Observed by Hinode/EIS: Quantifying the Departures from a Maxwellian Distribution