fl150.kundu02 Posted: 25-Oct-93 Updated: 24-Jul-94 Events specified: flaring XBP
M.R.Kundu (U.Md.),K.T.Strong (LPARL),M.Pick(Obs.Meudon),K.Harvey(NSO), S.R.Kane(U.C.B),S.M.White(U.Md),H.Hudson(U.HI.) A search was made for meter wave radio emission from more than a dozen coronal bright points as observed in soft X-rays by the Yohkoh/SXT experiment. The radio observations were obtained with the Nancay(France) Radioheliograph (NRH) at five frequencies in the range 150-450 MHz. Several cases of metric radio emission unambiguously associated with isolated flaring XBPs have been found based upon temporal and spatial coincidence of the XBP flares observed by Yohkoh and the radio emission observed by NRH.The metric radio emissions appear to be type III bursts,which are produced by nonthermal beams of electr ons:this represents strong evidence that the XBP- flare mechanism is capable of accelerating particles to nonthermal energies as well as heated material detected in soft X-rays.In one particular case to be discussed in this paper there is very good correspondence between the time profiles of the typeIII and the XBP flare.The radio bursts associated with XBP flares are very weak and nonspectacular in appearance, and are observed to be of restricted bandwidth. The detection of nonthermal emission is important for establishing the relationship between flaring XBPs and solar flares.
Update 24-Jul-94
Part of thie project has been completed.A paper has appeared in ApJ Letters, May 20,1994 issue.Authors ; kundu, Strong, Pick,Harvey,Kane,White,Hudson. Abstract of the work follows: Metric TypeIII Bursts from flaring X-ray bright Points
X-ray bright points are known to show variability on a number of different timescales, including impulsive X-ray brightenings.the relationship between these XBP flares and normal solar flares is poorly known.A fundamental question is whether nonthermal acceleration of particles takes place in XBP flares.We address this issue by searching for nonthermal radio emission at metric wavelengths from flaring XBPs identified in Yohkoh/SXT data.Unequivocal evidence for typeIII like radio bursts usually attributed to beams of nonthermal electrons on open field lines is found.This suggests that XBP flares are similar to normal flares and can indeed accelerate nonthermal populations of energetic particles.
There are more data in both radio and X-rays which remain to be analyzed.We have just started to write a second paper on the subject.