Multiwavelength Analysis of an X1.6 Flare of 2001 October 19

Abstract

An X1.6 two-ribbon flare was observed on 2001 October 19 using the imaging spectrograph at the Solar Tower of Nanjing University. We obtained a time series of two-dimensional Hα line spectra. Combining the observations by the Nobeyama Radioheliograph (NoRH), the Transition Region and Coronal Explorer (TRACE), the Yohkoh soft X-ray telescope (SXT) and hard X-ray telescope (HXT), and the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO), we performed a multiwavelength analysis for this flare in detail. The hard X-ray (HXR) and radio time profiles for this event have a double-peaked structure. Four Hα bright kernels exist, two of which are identified as the conjugate footpoints of a loop, while the other two are probably the footpoints of two different loops that are closely related. We compared the spatial distribution of the HXR sources with that of the Hα kernels at the two peak times. The results show quite asymmetric HXR emission in the Hα kernels. We ascribe this asymmetric behavior to the magnetic mirroring effect. In addition, we found that different heating mechanisms (nonthermal electron beam vs. heat conduction) may apply to different Hα kernels. We also derived the velocity field and found that the maximum velocity tends to occur at the outer edge of the flare ribbons. This is consistent with the general scenario of two-ribbon flare models.