Dynamical Fine Structure of a Quiescent Filament
Abstract
A quiescent filament was observed near the center of the disk (N5, W5) with the MSDP spectrograph of the 50 cm refractor of the PicduMidi Observatory on June 17, 1986. We focus our study on the statistical moments of the Dopplershift, V _{1}, and the intensity, I _{1}, at the center of a chord of the H α profile (±0.256 Å), versus the minimum intensity I _{0}. We use a statistical model simulating a number n _{max} of threads (of optical thickness τ _{0} and source function S _{0}), seen over the chromosphere. The threads j along the same lineofsight i are identical except for the velocity v _{j} (gaussian distribution v _{0}, σ _{v}). We search for the best fit between the observed and simulated quantities: V _{1}, σ ( V _{1}), I _{1}, σ( I _{1}), and the histogram of the I _{0} values over the field of view. A good fit is obtained with: (a) threads characterized by τ _{0} = 0.2, S _{0} = 0.06 (unit of the continuum at disk center), mean upward velocity v _{0} = 1.7 km s^{1} and gaussiantype velocity distribution σ _{v} = 3.5 km s^{1}. Other possible values of τ _{0} and σ _{v} are discussed; (b) underlying chromosphere deduced from observed quiet Sun (outside the filament) by modifying the chromospheric velocities: additional mean upward velocity 0.7 km s^{1}, standard deviation reduced by a factor F _{c} ∼ 0.7. The results are discussed in connection with the values deduced from prominence observations.
 Publication:

Solar Physics
 Pub Date:
 April 1994
 DOI:
 10.1007/BF00654083
 Bibcode:
 1994SoPh..151...75M
 Keywords:

 Chromosphere;
 Doppler Effect;
 Solar Prominences;
 Spectrum Analysis;
 Velocity Distribution;
 H Alpha Line;
 Histograms;
 Mathematical Models;
 Statistical Analysis;
 Solar Physics