We analyzed the full Stokes spectra using simultaneous measurements of thephotospheric (FeI 630.15 and 630.25 nm) and chromospheric (MgI b2 517.27 nm)lines. The data were obtained with the HAO/NSO Advanced Stokes Polarimeter,about a near disc center sunspot region, NOAA AR 9661. We compare thecharacteristics of Stokes profiles in terms of Doppler shifts and asymmetriesamong the three spectral lines, which helps us to better understand thechromospheric lines and the magnetic and flow fields in different magneticregions. The main results are: (1) For penumbral area observed by thephotospheric FeI lines, Doppler velocities derived from Stokes I (Vi) are veryclose to those derived from linear polarization profiles (Vlp) butsignificantly different from those derived from Stokes V profiles (Vzc), whichprovides direct and strong evidence that the penumbral Evershed flows aremagnetized and mainly carried by the horizontal magnetic component. (2) Therudimentary inverse Evershed effect observed by the MgI b2 line provides aqualitative evidence on its formation height that is around or just above thetemperature minimum region. (3) Vzc and Vlp in penumbrae and Vzc in poresgenerally approach their Vi observed by the chromospheric MgI line, which isnot the case for the photospheric FeI lines. (4) Outer penumbrae and pores showsimilar behavior of the Stokes V asymmetries that tend to change from positivevalues in the photosphere (FeI lines) to negative values in the lowchromosphere (MgI line). (5) The Stokes V profiles in plage regions are highlyasymmetric in the photosphere and more symmetric in the low chromosphere. (6)Strong red shifts and large asymmetries are found around the magnetic polarityinversion line within the common penumbra of the Delta spot. This study thusemphasizes the importance of spectro-polarimetry using chromospheric lines.
展开▼
