Monday, October 12, 2015 at 4:00 PM

JILA Auditorium

Shadia Habbal, IfA, U. Hawaii

"The Scientific Wealth of Total Solar Eclipse Observations"

Abstract:

In our current golden age of space exploration, images of the solar corona in the extreme ultraviolet (EUV) continue to yield unprecedented details of an extended solar atmosphere filled with complex filamentary structures down to subarcsec resolution, with time cadences of a few seconds, albeit limited to a field of view of less than half a radius above the solar surface. White light coronagraph images of the Sun from space, which currently span several tens of radii, on the other hand, capture filamentary structures streaming away from the Sun in the form of plasma blobs, jets and spectacular coronal mass ejections (CMEs). In these images, the inner corona, below a radius from the surface, is blocked by the inevitable necessity of a manmade disk to occult the bright solar disk in the visible wavelength range. The study of the complex expansion and evolution of the coronal plasmas and magnetic fields from the solar surface outwards into interplanetary space should, in principle, be empirically possible by combining these two types of observations. Unfortunately, by virtue of the inherent properties of the solar emission in these two wavelength ranges, namely the EUV and the visible, this link is missing.

At present, the only observing opportunity available to explore the evolution of coronal structures from the solar surface out to several solar radii is a total solar eclipse. Eclipse observations have historically led to the discovery of the solar corona, of helium, and of highly ionized charge states of Fe (hence a million degrees corona), to name a few. More recently, a number of discoveries have been made possible with the advent of digital photography, affordable scientific grade detectors, and state of the art image processing. This presentation will describe discoveries made over the last decade with broad-band white light and narrow-band multiwavelength images, and more recently with advanced spectroscopic techniques. The unique diagnostic potentials of the visible wavelength range for exploring the physics of the coronal plasmas and the source regions of the solar wind will also be underscored. Although a total solar eclipse is limited to a few minutes once every year at best, this cosmic event continues to present unmatched opportunities for unraveling some of the mysteries of our Star.

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