A coronal hole observed by 8-cm wavelength radioheliograph
Abstract
Around the end of 1975, a low brightness region was detected by an 8-cm radioheliograph at Toyokawa. It was observed over a period of three solar rotations. It was accompanied by a high-speed solar wind stream and caused recurrent-type geomagnetic storms. This region was identified as a coronal hole. The brightness temperature of this coronal hole was 6000 K lower than that of the normal quiet region. A simple model of the solar atmosphere was used to calculate the brightness temperature at 8-cm wavelength in the coronal hole and the normal quiet region. The electron pressure at the base of the corona obtained by EUV and soft X-ray observations is too high to explain the present radio observations of the coronal hole and the normal quiet region.
- Publication:
-
COSPAR, 20th Plenary Meeting
- Pub Date:
- June 1977
- Bibcode:
- 1977cosp.meetS....S
- Keywords:
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- Centimeter Waves;
- Solar Corona;
- Solar Radio Emission;
- Spectroheliographs;
- Atmospheric Models;
- Brightness Temperature;
- Far Ultraviolet Radiation;
- Magnetic Storms;
- Solar Physics