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Speaker: Silvano Fineschi, INAF, Italy
Time: 1:30 - 2:30 pm
Date: Wednesday, March 19, 2014
Location: CG1 - 1210 South Auditorium (also webcast at http://www.fin.ucar.edu/it/mms/cg-live.htm)
Title: Solar UV Polarimetry for Probing Coronal Magnetism
The high-temperature (1.e+4 to 1.e+7 K) plasmas in the solar upper atmoshpere and corona have strong emissions in the ultraviolet (UV and extreme ultraviolet (EUV) wavelength region (tens to hundreds nm). Spectro-polarimetric UV observations from space of these line-emissions, interpreted in terms of the Zeeman and the Hanle effects, are a powerful tool for the diagnostics of magnetic fields in the solar chromosphere/corona.
Through the anisotropic Doppler-dimmng effect, the linear polarization of optically thin spectral lines is sensitive to anisotropic ion-velocity distributions that can be induced by the ion-cyclotron resonance between plasmas and MHD waves in corona. This effect is believed to influence some heavy ions in the solar corona. Thus, coronal polarimetry of resonantly scattered UV spectral lines can also serve as a powerful tool for probing the magnetic field mechanism(s)of energy deposition in corona.
The past and current status of diagnostic and observing techniques for space UV polarimetry are briefly reviewed. The future prospectives are also described of new space instruments for implementing solar UV polarimetry.The goal of the talk is to give an overview of techniques based on polarimetry of EUV emission lines to obtain information on coronal magnetism and to assess the strengths and weaknesses of the techniques.