The total eclipse taking place on 2013 November 3 (at around 14:25 UT) will be observed from the ground with a suite of filters designed to isolate and measure the intensity of visible lines from selected key ions like Fe X, XI, XIII and XIV between 5000 A to 11000 A. As the field of view of the observation extends from the limb up to 4 solar radii, these measurements will provide a unique window on the physical properties of the extended solar corona, providing us with AIA-like 2D images of the solar corona, which hold the additional advantages over AIA of 1) better spectral/temperature purity and 2) 10 times larger effective field of view.
Emission lines in the visible are formed by radiative scattering of disk emission starting from approximately 1.1 Rsun. The combination of visible spectral lines with 1) collisionally dominated EUV coronal lines from EIS and 2) visible observations of the background continuum will allow us to apply unique spectroscopic diagnostic techniques that will provide:
1 - The first ever empirical determination of fast and slow solar wind freeze-in heights for Fe;
2 - The empirical determination of the frozen-in Fe charge state composition to be directly compared with in-situ data;
3 - An empirical model of the fast and slow wind velocity, electron temperature and electron density profiles from the limb to the freeze-in region using the novel technique developed by Landi et al. 2012 (ApJ, 750, 159)
4 - Large scale distributions of plasma parameters (electron density, temperature and filling factor) in streamers and coronal holes.
COMP observations of the Fe XIII 10747 and 10800 line pair will allowthe determination of the electron density below 1.5 solar radii to be compared with Hinode/EIS determinations, as well as cross-calibration between EIS, COMP and the eclipse observations.
We propose supporting observations from Hinode/EIS and Hinode/XRT during the eclipse, and for a few hours before and after the eclipse on 2013 November 3. The targets will be slowly evolving large-scale coronal structures (active region, streamer and coronal holes) before and after the eclipse.
During the eclipse we would like to observe a prominence cavity at the limb, which will allow us to easily co-align EIS observations with eclipse images. In the absence of a cavity, we will observe an active region at the limb. |
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