Flaring arches |
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| Authors: | Juan M Fontenla Zdeněk ?vestka Franti?ek Fárník Frances Y Tang |
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| Institution: | (1) The University of Alabama in Huntsville, U.S.A.;(2) Laboratory for Space Research Utrecht, SRON, The Netherlands;(3) Center for Astrophysics and Space Sciences, UCSD, 92093 La Jolla, CA, U.S.A.;(4) Astronomical Institute of the Czechoslovak Academy of Sciences, Ond ejov, Czechoslovakia;(5) Solar Astronomy, CALTECH, 91125 Pasadena, CA, U.S.A. |
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| Abstract: | We show detailed observations in X-rays, UV lines, and H of an extended arch, about 300000 km long, which developed as a consequence of a compact subflare. This subflare occurred in an  included magnetic polarity of relatively low magnetic field strength (compared to that of the sunspots). The apparition of this big arch was preceded by that of a smaller arch, about 30000 km long, which masked the polarity inversion line filament in the early phase of the subflare. The big arch which developed later, around the time of the main X-ray and UV spike of the subflare, connected the included polarity and the main leading sunspot of the region, and became fully developed in a few minutes. The fact that both arches were simultaneously observed in all spectral domains as well as their fine structure in H can only be explained by considering the arch as composed of several unresolved portions of material having widely different temperatures. The H observations can be interpreted as showing the appearance of this cool material as a result of condensation, but a more appealing interpretation is that there was almost simultaneous ejection of superhot (107 K), hot (106 K), mild (105 K), and cool (104 K) material from the subflare site along previously existing magnetic tubes of much lower density. The termination of the subflare was marked by a rather hard X-ray and UV spike which appeared to originate in a different structure than that of the main spike. The material in the arch gradually cooled and drained down after the end of the subflare.Member of Carrera del Investigador, CONICET, Argentina. |
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