PLASMA DYNAMICS ABOVE SOLAR FLARE SOFT X-RAY LOOP TOPS

We measure non-thermal motions in flare loop tops and above the loop tops using profiles of highly ionized spectral lines of Fe XXIV and Fe XXIII formed at multimillion-degree temperatures. Non-thermal motions that may be due to turbulence or multiple flow regions along the line of sight are extract...

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Bibliographic Details
Published in:The Astrophysical journal 2014-06, Vol.788 (1), p.1-13
Main Authors: Doschek, G A, McKenzie, D E, Warren, H P
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Atmospherics
Coverings
EXTREME ULTRAVIOLET RADIATION
Flares
Fluid dynamics
Imaging spectrometers
IRON
Line of sight
SOFT X RADIATION
SOLAR FLARES
SUN
Tops
TURBULENCE
VELOCITY
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Summary:We measure non-thermal motions in flare loop tops and above the loop tops using profiles of highly ionized spectral lines of Fe XXIV and Fe XXIII formed at multimillion-degree temperatures. Non-thermal motions that may be due to turbulence or multiple flow regions along the line of sight are extracted from the line profiles. The non-thermal motions are measured for four flares seen at or close to the solar limb. The profile data are obtained using the Extreme-ultraviolet Imaging Spectrometer on the Hinode spacecraft. The multimillion-degree non-thermal motions are between 20 and 60 km s super(-1) and appear to increase with height above the loop tops. Motions determined from coronal lines (i.e., lines formed at about 1.5 MK) tend to be smaller. The multimillion-degree temperatures in the loop tops and above range from about 11 MK to 15 MK and also tend to increase with height above the bright X-ray-emitting loop tops. The non-thermal motions measured along the line of sight, as well as their apparent increase with height, are supported by Solar Dynamics Observatory Atmospheric Imaging Assembly measurements of turbulent velocities in the plane of the sky.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/788/1/26