VLA observations of spatial structure in the quiet sun at 6 centimeters, during the 1977 October eclipse
Abstract
Observations of a quiet region on the solar disk were made during the partial solar eclipse of 1977 October 12, using the VLA at 4.9 GHz. Data from 21 baselines were used to make a series of one-dimensional synthesis maps as the Moon de-occulted the field of view. Taking successive differences of the one-dimensional maps and applying a coordinate transformation yielded a two-dimensional map in which the basic resolution was 2".5 × 12".7. The map showed that the small-scale structure of the region was dominated by a small number of compact sources, whose mean angular size and peak brightness temperature were in the range 9"-25" and (6-8) × 104 K, respectively. Although comparison with high-resolution Hα photographs showed no clear correlation with the chromospheric network, at least three of six source positions were consistent with the locations of small bipolar regions. This raises the possibility that the radio sources are associated with X-ray bright points.
Theoretical considerations based on published EUV data show that the observed microwave structure cannot be explained by the normal chromospheric network. The available soft X-ray and EUV data are consistent, however, with the hypothesis that the microwave sources represent X-ray bright points.- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1980
- DOI:
- 10.1086/157828
- Bibcode:
- 1980ApJ...236.1017M
- Keywords:
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- Solar Eclipses;
- Solar Physics;
- Solar Radiation;
- Solar X-Rays;
- Antenna Arrays;
- Astronomical Maps;
- Brightness Temperature;
- Radio Interferometers;
- Spatial Distribution;
- Spectroheliographs;
- Solar Physics