New measurements of the polarization of X-ray solar flares

Measurements of three X-ray flares in October/November 1970 abord the Intercosmos 4 satellite confirm the existence of polarization in the initial phase of the X-ray bursts. The polarization can be observed for a few up to ten minutes, and an increase in polarization is observed during secondary maxima of the bursts as well.     

On the localization,size and structure of the regions of the X-ray flares on the Sun

With the use of X-ray heliographs carried by the satellites Cosmos-166 and Cosmos-230 the height of an X-ray flare was found to be about 20–25 000 km. The regions of the X-ray flares possess a filamentary structure which, during the development of the flares, shows spatial changings with speeds up to 10⁷ cm/sec.     

On the polarization of the emission of X-ray solar flares

X-ray polarization measurements at three flares occurred in October 1969 were performed by means of a Thomson scattering type instrument installed on board the satellite Intercosmos-1. The polarization (P) at the wavelength of about 0,8 Å was detected at the rising phase and at the second maximum of intensity. The obtained averaged value of P for all three flares is 0.4 ± 0.2 at confidence level 0.9.     

Further polarization measurements of the solar flare X-ray emission

An improved X-ray polarimeter is briefly described and preliminary results of the measurements carried out on the satellite Intercosmos-7 are presented. One flare with considerable polarization (P 16%) was observed on 1972 August 4. Two other flares with rather low polarization (P 4%; P 2%) were observed on 1972 August 7 and 11.