Simultaneous Multifrequency Observations of an Eruptive Prominence at Millimeter Wavelengths
Abstract
Radio images and spectra of an eruptive prominence were obtained from simultaneous multifrequency observations at 36 GHz, 89 GHz, and 110 GHz on May 28, 1991 with the 45-m radio telescope at Nobeyama Radio Observatory (NRO), the National Astronomical Observatory, Japan (NAOJ). The radio spectra indicated that the optical depth is rather thick at 36 GHz whereas it is thin at 89 and 110 GHz. The Hα data, taken at Norikura Solar Observatory, NAOJ, suggest that the eruption of an active region filament was triggered by an Hα flare. The shape and position of the radio prominence generally coincided with those of Hα images. The radio emission is explained with an isothermal cool thread model. A lower limit for the electron temperature of the cool threads is estimated to be 6100 K. The range of the surface filling factors of the cool threads is 0.3-1.0 after the Hα flare, and 0.2-0.5 in the descending phase of the eruptive prominence. The column emission measure and the electron number density are estimated to be of the order of 1028 cm−5 and 1010 cm−3, respectively. The physical parameters of a quiescent prominence are also estimated from the observations. The filling factors of the eruptive prominence are smaller than those of the quiescent prominence, whereas the emission measures and the electron densities are similar. These facts imply that each cool thread of the prominence did not expand after the eruption, while the total volume of the prominence increased.
- Publication:
-
Solar Physics
- Pub Date:
- February 1995
- DOI:
- 10.1007/BF00670232
- Bibcode:
- 1995SoPh..156..363I
- Keywords:
-
- Millimeter Waves;
- Solar Physics;
- Solar Prominences;
- Solar Radio Emission;
- Solar Spectra;
- Sun;
- Electron Density (Concentration);
- H Alpha Line;
- Radio Spectra;
- Solar Flares;
- Solar Physics;
- Filling Factor;
- Emission Measure;
- Radio Telescope;
- Electron Number Density;
- Radio Image