Ts. S. Khetsuriani

Solar investigations at Abastumani Astrophysical Observatory of the Academy of Sciences of Georgia, U.S.S.R.

The paper deals with the review of works on solar observations at Abastumani Astrophysical Observatory during the past 12 years. The works accomplished on the basis of patrol observations, with the horizontal solar telescope, small and large coronagraphs, and those based on the data obtained during eclipse observations are discussed separately.

The results of coronal investigation at the September 22, 1968 solar eclipse

The 1968 Abastumani Astrophysical Observatory Solar Eclipse Expedition obtained photographic records of the polarization and intensity of the solar corona on September 22 from a site of the South Urals (Western Siberia). A photometric study of the corona was carried out. Polarization has been computed both in a total corona and in some of its streamers. The coronal intensity Ik and IF components are separated. Electron concentrations and temperatures are computed.

On the formations connected with the limb flare of November 6, 1979

We analyzed the observation data obtained at Abastumani astrophysical observatory in the form of spectrograms and filtergrams of formations associated with the November 6, 1979 limb flare. We studied the system of flare loops, the late stage of the bright flare loop development, and postflare coronal loops obtained inHα and coronal lines. The physical parameters of the structures observed as well as their dimensions and mutual locations are determined. The Doppler velocities at different altitudes are measured and the prevailing upward direction of the matter motion in the flare loops is revealed.

A Polarization Investigation of Prominences

A theoretically possible value of the polarization in various spectral lines is determined by quantum mechanical parameters of corresponding transitions (Chandrasekar, 1953). From this standpoint the resonance line of CaI λ4227 (4151-41P0) is very convenient for polarization measurements as the polarization predicted theoretically for this line is high (~100%). In D3 He (λ5876 33D - 23P) line consisting of three components the theoretical polarization in the whole line does not exceed 24%. But in the long wave component of the multiplet λ5875.989 whose intensity is ten times lower than that of the primary line the polarization is about 100%. Therefore based on the data obtained with high spectral resolution the polarization investigations of these lines can be performed using the method of photographic photometry. Particularly for high prominences, as it is known due to Baumbach’s (1938) calculations, the polarization of prominence radiation increases with the distance from the solar limb.