Interferometer observations of Type III, Type II and Type IV bursts at 20 and 25 MHz on 29 May 2014

Valentin Melnik, Institute of Radio Astronomy of National Academy of Sciences of Ukraine

Results of interferometer observations of Type IV durst, Type III bursts and Type II bursts by the UTR-2 radio telescope at frequencies 20 and 25 MHz on 29 May 2014 are discussed. For interferometer observations we used 4 sections of west-east arm of UTR-2 the radio telescope. These observations were supported by the URAN-2 radio telescope observations in the usual spectrographic regime. There were eight bright Type III bursts, some parts of Type II burst and Type IV burst during the event happened from 9:06 till 11:15 UT. We found that the source of the stationary Type IV burst was situated at the distance of 30-35 arcmin at both frequencies and had unchanged sizes of 27 and 37 arcmin at frequencies 25 and 20 MHz correspondingly. Parts of Type II burst and their fine structures were at distances from 25 to 30 arcmin at these frequencies. Their sizes were in the range 10-24 arcmin. We also measured distances and sizes of eight bright Type III bursts occurred from 9:06 to 11:15 UT. Sources places were turned out to be about 41-43 and 45-47 arcmin from the center of the Sun. At these distances radio emission at frequencies 25 and 20 MHz are radiated at the second harmonic in the Newkirk model. This result is confirmed by the low polarizations of all Type III bursts, which according to URAN-2 radio telescope were not higher than 5%. Sizes of Type III sources were 20-22 and 24-27 arcmin at frequencies 25 and 20 MHz correspondingly. This gives the brightness temperatures of Type III bursts in the range 2x10^9- 4x10^10 К. We also found that velocities of Type III electrons were 0.2-0.3c.