Astronomy and Astrophysics – Astrophysics
Scientific paper
Dec 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009agufmsh41b1659c&link_type=abstract
American Geophysical Union, Fall Meeting 2009, abstract #SH41B-1659
Astronomy and Astrophysics
Astrophysics
[7509] Solar Physics, Astrophysics, And Astronomy / Corona, [7549] Solar Physics, Astrophysics, And Astronomy / Ultraviolet Emissions
Scientific paper
The determination of non-thermal line broadening and velocities from the spectral linewidth measurements in the EUV provide an observational limits to available energy from unresolved sources within the observed coronal structures. These non-thermal velocity components can result from a number of sources including wave motions , turbulence, and electron beam interactions among others each of which has been suggested as a possible means of generating the required energy for the coronal heating process. .This study presents the determination and statistical analysis of the non-thermal velocity components of 397 identified EUV spectral lines from the combined observations of the SERTS 1991-1997 flights covering the wavelength range from 174-418Å. Similar analysis is also presented for the distributions of active region, quiet sun, and off-limb emission lines respectively which combine to form the composite distribution. We find, for all four of these velocity distributions, a strong non-thermal velocity peak corresponding to a velocity of 20-24 km/s regardless of location or activity level. These velocities suggest the majority of SERTS observed lines do not produce sufficient energy within their non-thermal components to contribute significantly to the heating process and are likely instead to observed motions of plasma cooling into the SERTS temperature range, peaked near 1.4 MK. The active region velocity distribution, however, exhibits evidence of a multi-component distribution through the existence of a high velocity shoulder which can be fit with a secondary distribution peaking near 47 km/s. This higher velocity component, does possess enough energy to overcome typical energy losses and potentially contribute to the available energy of the observed coronal plasma.
Coyner Aaron J.
Davila Jose Manuel
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