Physics
Scientific paper
Sep 1991
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1991soph..135...89f&link_type=abstract
Solar Physics (ISSN 0038-0938), vol. 135, Sept. 1991, p. 89-97.
Physics
8
Calcium, K Lines, Line Shape, Metal Ions, Solar Flares, Charge Coupled Devices, Emission Spectra, H Alpha Line, Line Spectra
Scientific paper
Two-dimensional evolutions of two flares of October 18, 1990 have been well observed in the Ca II K line with a CCD camera at Norikura station of National Astronomical Observatory in Japan. There are two common characteristics for the flares: 3 - 5 min before the impulsive phase, the heating already begins at the footpoints of the flares, but no asymmetry in line emission has been detected. After the onset of the impulsive phase, Ca II K line emission at the footpoints shows strong red asymmetry, with the maximum asymmetry occurring at the same time as the peak of the radio bursts. The maximum downward velocity is about 30-50 km/s. For flare 1, blue and red asymmetries were observed in two sides of the footpoint area. They developed and attained a maximum nearly at the same time and the inferred Doppler velocities are comparable (30-40 km/s). This implies that two mass jets started from a small region and ejected along a loop but in opposite directions with roughly equivalent momentum. A possible mechanism has been discussed.
Fang Chen
Hiei Eijiro
Okamoto Tohru
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