Daily variations of the photospheric equatorial rotation velocity of the sun and its absolute values in 1981 and 1982 as determined from measurements using a two-dimensional photodiode array
Abstract
Doppler velocity measurements using the solar spectral line Fe I 6301.5 Å and the terrestrial O2 line at 6302.0 Å as a reference were used to determine the equatorial rotation velocity of the solar photosphere. The spectral lines were recorded by a two-dimensional photodiode array.
The absolute values of the rotation velocity were 1988 m/s in April 1981 and 1953 m/s in May 1982. The daily variations did not exceed 10 m/s when time averages of several hours existed. The comparison with results from other observes and other observatories shows the same behaviour from 1981 to 1982: a decrease of the rotation velocity by about 35 m/s. But neither the absolute values nor the daily changes are in good agreement with other observations.- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 1983
- Bibcode:
- 1983A&A...123...29K
- Keywords:
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- Angular Velocity;
- Photodiodes;
- Photosphere;
- Solar Rotation;
- Diurnal Variations;
- Doppler Effect;
- Velocity Measurement;
- Solar Physics