ON THE STRUCTURE OF 3.11.94 ECLIPSE CORONA

We present the results of our observations of the white-light corona in polarized light performed at Criciuma eclipse, Brazil.

During the observation of 3.11.94 we have made five couple of pictures of the solar corona in polarization light. The telescope with equatorial mounting with LOMO lens diameter D = 7.5 cm and focus f = 75 cm used in the observation.

Fig.1. Optical scheme of the instrument.

To suppress the radial gradient of the coronal emission it was used an mask of diameter d = 3 cm puted between the lens and the film at a distance l = 25 cm from the focal plane. Radius R and the focal length f of the lens were selected in such a way to provide complete blinding of the lens at the moon edge and a full opening of the lens at the distance g from the centre of the 6x6 cm picture. Couples of pictures with exposures 2, 4, 8, 16 and 32 sec were made. Revealed fine structure of the streamers allowed to perform careful analysis of the solar corona structure.

Fig.2. Images of the corona in polarized light.
Fig.3. Computed stereo-diagram of the 3-D structure of the = 0 surface. The polarization degrees are marked by the colors: red (0 - 20%), yellow ( 21 - 40%), orange ( 41 - 60%), blue ( 61 - 80%), dark blue ( 81 - 100%).

Fig.4. Plot of the polarization degree and structural drawing of the corona for 3.11.96.

We propose new method of reconstructing the ray structure of the solar corona for distances more than 1.5 from photosphere.

The method based on the calculation of the =0 surface. It was used the photospheric data as boundary conditions and assumed potential approximation for the magnetic field with this approach, we have built a =0 surface for 3.11.94. In our empirical model large streamers are represented as folds and pleats of the thin geliospheric current sheet adjacent to the = 0 surface.

In the present work we test the assumptions underlying our method of calculating the coronal sheet near = 0 and compare the obtained results with the observations of the corona of 3.11.94. Clear correspondence of the observed ray structures to the configuration of the observed ray structures to the configuration of the folds. This result is a very important confirmation of the adequacy of the our approach.

The same conclusion can be derived from the analysis of the polarization of main rays. The greatest of the polarization is observed for the points located along the direction of the maximal extent of the corona.

References:

Koutchmy S., Molodensky M., Starkova L., Ershov A., Matsuura O.: 1995, Proceedings of the International Symposium on the Total Eclipse of November 3, 1994. Revista de la Academia Nacional de Ciencias de Bolivia 69, 60-71.

Molodensky M., Starkova L., Koutchmy S., Ershov A.: 1996, Solar Drivers of Interplanetary and Terrestrial Disturbances ( Ed. K.S.Balasubramaniam, S.Keil, and R.Smart ), 385-392.

Molodensky M.M., Starkova L.I., Koutvitsky V. and Ershov A.: 1996, Astronomicheskii Zhurnal, 73, 934-938.

Koutchmy S., Molodensky M.M., Starkova L.I. Koutvitsky V. and Ershov A.: 1996, Izvestia VUZov, Radiofizika 39, 1381-1388.

Koutchmy S., Molodensky M.M., Starkova L.I. Koutvitsky V. and Ershov A. : 1997, Pis'ma v Astronomicheskii Zhurnal, 23, 939-948.