The Sun at 8.5 mm wavelength ? results of observations with high angular resolution

High-resolution single dish observations of the solar radio emission with the Effelsberg 100-m telescope at 8.5-mm wavelength (antenna beam width is 31") show a good correlation of small active regions seen in quiet Sun areas, associated with the longitudinal magnetic fields, but not with structures seen in H alpha light. Some characteristics of these 8.5-mm structures, such as diameter and temperature, point to a correlation with supergranular cells. Although the lifetime of these structures is longer than several hours, weak intensity variations within a time scale of minutes could be recorded. From the observational results, it was possible to derive an approximate energy dissipation rate for the 8.5-mm structures. This value is a factor of 100 higher than that obtained earlier at 2.8-cm wavelength in a similar manner. A center-to-limb variation at 8.5 mm, especially a limb brightening, could not be detected.