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Invisible Tools for Measuring Intangible Fields: Polarimetry for the Detection and Mapping of Solar Magnetic Fields

Event Details

Event Dates: 

Monday, April 15, 2013 - 10:00am

Speaker Name(s): 

Rafael Manso-Sainz

Speaker Affiliation(s): 

Instituto de Astrofisica de Canarias
Seminar Type/Subject

Event Details & Abstract: 

Magnetic fields are what make the solar atmosphere and its outer layers so interesting: they disturb the 'normal' fluid motions forcing the plasma to behave in counterintuitive ways; upper in the atmosphere they compete with gravity keeping the plasma levitating; and they may even be able to eject plasma out towards the interplanetary medium, with important consequences for us here on Earth. However, all this complex behavior is difficult to understand because solar magnetic fields are notably difficult to detect and quantify. They cannot be 'seen' directly; the only quantitative evidence of their presence is through the only property of light we cannot see with our own eyes: polarization.Yet, solar physicists were able to develop spectropolarimetric techniques for the remote sensing of magnetic fields from 90 million miles away. These techniques require the application of advanced optics technology, radiative transfer theory, and quantum mechanics, in order to be able to observe, analyze, and interpret the subtle spectropolarimetric signatures of solar magnetic fields. I will review standard diagnostic techniques and recent developments in this field. I will discuss limitations of these techniques, and how to overcome them through the complementary use of different diagnostic techniques, spectral regions, and statistical analysis. Finally, I will review the main areas for progress in this field: most notably, the 'measurement' of magnetic fields in the extremely dilute and weakly magnetized outer layers of the sun.