Astronomy and Astrophysics, volume 391, 741-748 (2002/8-4)
Multi-wavelength observations of a flare spray and CME of 1 October 2001.
LI H., YOU J., YU X. and WU Q.
Abstract (from CDS):
Using the Multi-channel Infrared Solar Spectrograph (MISS) at the Purple Mountain Observatory (PMO), we obtained the Hα, CaII 8542Å, HeI 10830Å spectra and slit-jaw Hα images of a large dramatic flare spray near the south-west solar limb on 1 October 2001. For this event, we also got Extreme-Ultraviolet (EUV) images at 171Å from TRACE and 195Å from EIT/SOHO, coronal images from the C2 and C3/LASCO coronagraph on SOHO, soft X-ray (SXR) images from the Soft X-ray Telescope (SXT) and hard X-ray (HXR) flux from the Hard X-ray Telescope (HXT) onboard Yohkoh, X-ray flux from GOES, and Hα images and radio-frequency spectrograms from the National Astronomical Observatories of China (NAOC). The complex eruption event lasted about 40 min and was composed of two flaring and three distinct mass ejecting processes. The preliminary analysis leads to the following results: (1) the three peak-times on the HXR light curves correspond to the interactions and reconnections of coronal loops shown on the SXR images and are consistent with the flaring times in Hα; (2) the first mass ejection process of this event is apparently related to the loop interaction and magnetic opening and reconnection, while the second mass ejection, i.e., the large flare spray, is associated with the second flare. There are bright fine arcs connecting the onset location of the spray and the footpoints of the flare loops. The rising speeds the three ejections in the sky plane are all 296 km.s–1 and uniform in the early phase; (3) comparisons show that the flare spray has nearly the same shape in Hα, 171Å, 195Å and SXR images, which implies that plasma with temperatures differs by a factor of more than 100 can exist in the same spray and move by about 2x105km with the same shape; (4) we infer from the height-time curves of the spray and CME that the observed CME by LASCO is closely related to the flare spray. However, we could not conclude what the trigger of the CME is due to the lack of more direct and convincing evidence, such as images from the LASCO C1 coronagraph. Meanwhile, the CME is accelerated at about 2 R☉ presumably due to change in the large-scale magnetic field structure; (5) in the initial phase of the spray, all the Hα, CaII 8542Å and HeI 10830Å spectra show unusually broadened profiles and large blue-shift velocities, and the maximum of the line-of-sight velocity reaches 286km/s.