Coronal Euv and Radio Variability And

We present sensitive coronal line (Fe IX and Fe XII) observations by the Extreme ultraviolet Imaging Telescope (EIT) onboard the SOHO satellite. The thermal emission of the quiet corona is detected to uctuate in time and space, presumably the result of localized heat inputs. Signiicant uctuations are found in 85% of all pixels. The more prominent enhancements are identiied with previously reported X-ray network ares above the magnetic network of the quiet Sun chromosphere. In coronal EUV lines they are amenable to detailed analysis suggesting that the brightenings are caused by additional, dense plasma injected from below and heated to slightly higher temperature than the preexisting corona. An associated radio enhancement at 3.6 or 6 cm wavelength is found in most cases. About half of them show decreasing spectra indicating gyrosynchrotron radiation. Such radio signature is suggestive of non-thermal electrons well-known as an important constituent of regular ares. Therefore we propose that these enhancements are indeed microoares produced by a reconnection process in the corona. Assuming that these ndings apply to all observed EUV enhancements, their energy input would correspond to one fth of the heating requirement of the quiet corona. These observations give convincing evidence for the rst time that microoare heating is a signiicant process.