Solar Eclipses Reveal Iron Line In Solar Corona

Solar Eclipses Reveal Iron Line In Solar Corona

Solar Eclipses Reveal Iron Line In Solar Corona

This image of the solar corona contains a color overlay of the emission from highly ionized iron lines and white light taken of the 2008 eclipse. Red indicates iron line Fe XI 789.2 nm, blue represents iron line Fe XIII 1074.7 nm, and green shows iron line Fe XIV 530.3 nm. This is the first such map of the 2-D distribution of coronal electron temperature and ion charge state. Credit: Habbal, et al. More images

Solar physicists attempting to unlock the mysteries of the solar corona have found another piece of the puzzle by observing the Sun's outer atmosphere during eclipses.

Ground-based observations reveal the first images of the solar corona in the near-infrared emission line of highly ionized iron, or Fe XI 789.2 nm.

The observations were taken during total solar eclipses in 2006, 2008, and 2009 by astrophysicist Adrian Daw of NASA's Goddard Space Flight Center in Greenbelt, Md., with an international team of scientists led by Shadia Habbal from the University of Hawaii's Institute for Astronomy (IfA).

"The first image of the corona in Fe XI 789.2 nm was taken during the total solar eclipse of March 29, 2006," said Daw.

The images revealed some surprises. Most notably, that the emission extends out at least three solar radii - that's one-and-a-half times the Sun's width at its equator, or middle - above the surface of the Sun, and that there are localized regions of enhanced density for these iron ions.