All Figures

Figure 1: Superimposed observations for all the limb distances listed in Table 1. The Stokes parameters Q and U are expressed in the limb reference frame. Dotted lines: intensity I in arbitrary units. The slit has been positioned parallel to the solar limb and the data have been averaged along the slit (one arcmin long) to increase the polarimetric sensitivity. The Sr I line is 460.7333 nm and the neighboring line at 460.7651 nm is a Fe I line that depolarizes the continuum. The broken line is the theoretical value of the limb polarization to which the observed continuum polarization has been superimposed (see text for details).

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In the text

Figure 2: Superposition of adjusted theoretical profiles (lines) and observations (dots) of 2002 December 7 and 9. The theoretical intensity profiles have been computed in a non-magnetized atmosphere and are used to determine  and . Given these values, the theoretical polarization profiles, adjusted to the observations at line center only, are used to determine the microturbulent field strength B from the magnetized atmosphere model.

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In the text

Figure 3: Top: center-to-limb variation of the observed linear polarization (dots), with an exponential least square fit (line, see Eq. (22)), together with the values of the determined microturbulent field strength in Gauss. Bottom: microturbulent field strength in Gauss, as a function of the height above the  level in km. This height results from our line opacity evaluation (see text). The error bars show the effect of the polarimetric inaccuracy only, the theoretical data being assumed to be sure at this stage. The line is a least square fit whose equation is provided.

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In the text