Spectroscopic Coronal Observations during the Total Solar Eclipse of 11 July 2010

TL;DR

This study captures spectroscopic observations of the solar corona during the 2010 total solar eclipse, revealing variations in coronal emission lines and identifying weak lines associated with high excitation regions.

Contribution

It provides new spectroscopic data during a solar eclipse at the beginning of Solar Cycle 24, highlighting differences from previous cycles and detecting weak emission lines in the corona.

Findings

Observed variations in red and green coronal line intensities compared to 2008 eclipse.

Detected forbidden Ca XV emission line in high excitation regions.

Measured chromospheric height using spectral lines from light and heavy elements.

Abstract

The flash spectrum of the solar chromosphere and corona was measured with a slitless spectrograph before, after, and during the totality of the solar eclipse, of 11 July 2010, at Easter Island, Chile. This eclipse took place at the beginning of the Solar Cycle 24, after an extended minimum of solar activity. The spectra taken during the eclipse show a different intensity ratio of the red and green coronal lines compared with those taken during the total solar eclipse of 1 August 2008, which took place towards the end of the Solar Cycle 23. The characteristic coronal forbidden emission line of forbidden Fe XIV (5303 {\AA}) was observed on the east and west solar limbs in four areas relatively symmetrically located with respect to the solar rotation axis. Subtraction of the continuum flash-spectrum background led to the identification of several extremely weak emission lines, including forbidden Ca XV (5694 {\AA}), which is normally detected only in regions of very high excitation, e.g., during flares or above large sunspots. The height of the chromosphere was measured spectrophotometrically, using spectral lines from light elements and compared with the equivalent height of the lower chromosphere measured using spectral lines from heavy elements.