Shape of the sun
This thesis describes the design, construction, and operation of a telescope capable of measuring the shape of the sun to an accuracy of about one milliarcsecond. The instrument is similar to that used by Dicke in 1966, but with added angular resolution around the solar limb to detect the presence of photospheric fuculae and sunspots. Data were collected on 131 days in the 5-month period May-September 1983 at Mt. Wilson, California. A solar oblateness of ..delta..r = r/sub equator/-r/sub pole/ = 12.8 +/- 2.4 milliarcseconds was measured for the period, where the sun's radius is 960 arcseconds. The 12-day rotating distortion seen in '66 was not detected in the present data set, nor were any higher-frequency oscillations. These reuslts are consistent at the 2sigma level with the oblateness ..delta..r = 7.8 milliarcseconds expected from the sun's surface rotation alone, and inconsistent with Dicke's '66 results. There is some indication in the data that there exists a polar temperature excess of T/sub pole/-T/sub equator/ approx. = 4/sup 0/C in the quiet photosphere. Solar faculae and anomalous lensing effects in the earth's atmosphere were found to be the major sources of systematic error in the measurement, but neither of these error sources can explain the '66 data. In fact no explanation (other than a changing sun) was found for the discrepancy between the two measurements.
- Research Organization:
- Princeton Univ., NJ (USA)
- OSTI ID:
- 5988291
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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