Observing the solar corona with a tunable Fabry-Perot filter.
Matthew W Noble1, David M Rust, Pietro N Bernasconi
1Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland 20723, USA.
Applied Optics
|January 6, 2009
Summary
Researchers used a specialized Fabry-Perot etalon during a solar eclipse to rapidly scan the solar corona. This allowed detailed observation of the [Fe X] emission line, revealing coronal structures and velocities.
Area of Science:
- Solar Physics
- Coronal Plasma Studies
- Spectroscopy
Background:
- The solar corona is a dynamic outer atmosphere of the Sun.
- Understanding coronal plasma requires high-resolution spectral analysis of emission lines.
- Observational challenges exist due to the faintness and rapid changes in coronal structures.
Purpose of the Study:
- To utilize a novel solid Fabry-Perot etalon for rapid spectral scanning of the solar corona.
- To observe the [Fe X] emission line during a solar eclipse to map coronal structure.
- To investigate the velocity of coronal plasma features.
Main Methods:
- Employed a Y-cut lithium niobate Fabry-Perot etalon with a 0.16 A passband.
- Used voltage-controlled passband shifting (0.0011 A V(-1)) for spectral scanning.
- Acquired 18 filtergrams across the [Fe X] line profile (6374.4 A) during a 180 s solar eclipse.
Main Results:
- Successfully mapped the structure of the solar corona above a sunspot region.
- Obtained detailed spectral profiles of the forbidden [Fe X] emission line from 10(6) K plasma.
- Detected coronal features with line-of-sight velocities as low as 10 km s(-1).
Conclusions:
- The solid Fabry-Perot etalon is effective for rapid coronal spectral analysis.
- Eclipse observations provide valuable insights into coronal structure and dynamics.
- The study demonstrates the capability to measure subtle velocity variations in coronal plasma.
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