Aris Voulgaris, Paul Gaintatzis, John H. Seiradakis, Jay M. Pasachoff, Thanasis E. Economou
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.
View original:
http://arxiv.org/abs/1202.1535
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