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Coordinated observations obtained at Meudon (MSDP) and at Ondejov provide surge spectra in optical range (H, H, H, Hµ, Ca H and K lines) and in radio range. The MSDP data allowed us to follow the time evolution of the surge. The spectra of Balmer lines were used to derive the electron density of the expelled cool material. The radio bursts indicate that the acceleration of electrons took place in the low and dense atmosphere, giving a good argument for a reconnection near the transition region. 相似文献
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MEIN P. MEIN N. MALHERBE J.-M. HEINZEL P. KNEER F. VON UEXKULL M. STAIGER J. 《Solar physics》1997,172(1-2):161-170
A small flare was observed at the Teide Observatory on October 5, 1994. Simultaneous data were obtained at the German Vacuum Tower Telescope (VTT) with the MSDP spectrograph providing high-resolution imaging spectroscopy in two chromospheric lines, and the Gregory Coudé Telescope (GCT) providing information about the magnetic field. Basic flare characteristics are:The area of the flare kernel ( 2 x 2 arc sec) is similar in H and Caii 8542 Å.The early phase of the flare is characterized by a blue asymmetry in H and a red one in Caii 8542 Å line.The evolutions of line profiles are different; the red asymmetry observed in the Caii line is detected a few seconds later in H.The maximum asymmetry of the Caii line does not coincide with the maximum brightness.The flare occurs in a region of a strong horizontal gradient of the line-of-sight component of the magnetic field.Brightness and asymmetry in H and Caii are discussed in the context of standard flare models and velocity fields. Our observations suggest that a magnetic reconnection could occur at low levels of the solar atmosphere. 相似文献
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