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Measurement of Aerosols Optical Thickness of the Atmosphere using the GLOBE Handheld Sun Photometer
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Solar Diameter Monitor: an instrument to measure long-term changes.
T M Brown1, D F Elmore, L Lacey
1National Center for Atmospheric Research, High Altitude Observatory, PO Box 3000, Boulder, Colorado 80307, USA.
Applied Optics
|April 17, 2010
Summary
Scientists are monitoring the Sun's diameter for variations using a new automated telescope. This research aims to detect subtle changes in solar diameter over time, contributing to our understanding of solar physics.
Area of Science:
- Solar Physics
- Astronomy
- Stellar Evolution
Background:
- Historical data analysis indicates potential variations in the Sun's diameter.
- Such variations, if present, could have amplitudes of tenths of an arcsecond.
- Understanding solar diameter constancy is crucial for solar models.
Purpose of the Study:
- To design and deploy a specialized instrument for detecting solar diameter changes.
- To achieve a high level of precision in measuring the Sun's diameter.
- To test the hypothesis of a varying solar diameter over time.
Main Methods:
- Utilized a custom-built, automated f/50 transit instrument, the Solar Diameter Monitor.
- Employed automated measurements at solar noon to minimize observer bias.
- Measured horizontal diameter via solar disk transit time and vertical diameter against a stable length standard.
Main Results:
- The Solar Diameter Monitor is designed for high-precision solar diameter measurements.
- Preliminary estimates indicate the capability to test solar diameter constancy at the 1-arcsec/century level.
- An observing period of 3-5 years is projected for robust analysis.
Conclusions:
- The developed instrument offers a novel approach to studying solar diameter variations.
- The study aims to provide empirical evidence regarding the Sun's diameter stability.
- Findings will contribute to refining solar models and understanding solar dynamics.
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