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Analysis of the microwave data, obtained in the 17 GHz channel of the Nobeyama Radioheliograph during the M1.6 flare on 4th Nov 2010, revealed the presence of 11.8-min oscillations of the emitting plasma density. The oscilla- tions decayed with the characteristic time of about 25-min. These oscillations are also well-seen in the variation of EUV emission intensity measured in the 335 A channel of SDO/AIA. The observed properties of the oscillations are consistent with the properties of so-called SUMER oscillations, observed in the EUV and soft X-ray bands usually as a periodic Doppler shift. The accepted interpretation of SUMER oscillations is a standing slow magnetoacoustic wave. Our analysis presents the first direct observation of the slow magnetoacoustic oscillations in the microwave emission of a solar flare., Comment: 12 pages, 4 figures

We found systematic microwave source motions along a flare-arcade using Nobeyama Radioheliograph (NoRH) 17 GHz images. The motions were associated with a X-class disk flare which occurred on 15th February 2011. For this study, we also used EUV images from Atmospheric Imaging Assembly (AIA) and magnetograms from Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory, and multi-channel microwave data from Nobeyama Radiopolarimeters (NoRP) and Korean Solar Radio Burst Locator (KSRBL). We traced centroids of the microwave source observed by NoRH 17 GHz during the flare and found two episodes of the motion with several facts: 1) The microwave source moved systematically along the flare-arcade, which was observed by the AIA 94 A in a direction parallel to the neutral line. 2) The period of each episode was 5 min and 14 min, respectively. 3) Estimated parallel speed was 34 km/s for the first episode and 22 km/s for the second episode. The spectral slope of microwave flux above 10 GHz obtained by NoRP and KSRBL was negative for both episodes, and for the last phase of the second episodes, it was flat with the flux of 150 sfu. The negative spectrum and the flat with high flux indicate that the gyrosynchrotron emission from accelerated electrons was dominant during the source motions. The sequential images from the AIA 304 A and 94 A channels revealed that there were successive plasma eruptions and each eruption was initiated just before the start time of the microwave sources motion. Based on the results, we suggest that the microwave source motion manifests the displacement of the particle acceleration site caused by plasma eruptions., Comment: 14 pages, 6 figures

We have investigated a supra-arcade structure, associated with an M1.6 flare, which occurred on the south-east limb on 4th of November 2010. It is observed in microwaves at 17 GHz with the Nobeyama Radioheliograph (NoRH), soft X-rays in the range of 8-20 keV with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), and EUV with the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). As reported by Reeves & Golub (2011), the supra-arcade structure is observed predominantly in the AIA 131 {\AA} channel, which contains a hot 11 MK component from Fe XIX (Boerner et al. 2011). While this hot flare plasma lasts over the decay phase of the flare, it shows some interesting characteristics in microwaves and soft X-rays: 1) In the supra-arcade structure, the brightness temperature (TB) of the microwave emission increases gradually up to 2\times10^4 K, and 2) two soft X-ray sources appear: one cospatial with the supra-arcade structure and another above the post-flare arcade. We have derived the variation of emission measure, density, and energy of the supra-arcade structure using the TB obtained from 17 GHz microwave observations., Comment: Submitted to the proceeding for The 11th Asian-Pacific Regional IAU Meeting 2011 NARIT Conference Series, Vol. 1