Color of the Corona Continuum of July 11, 1991

The color of the coronal continuum was determined from observations in order to search for manifestations of coronal expansion. A brief review of studies determining the color of the coronal continuum finds that the previously obtained results are inconsistent. The color index for the coronal continuum is defined. The necessity of the use of a relative color index is substantiated.RCIestimates of expected values are made with respect to the electron speed. A two-dimensionalRCIdistribution for the corona of July 11, 1991, was constructed. Comparison of the distribution with the coronal structure illustrates the absence of uniformity of the coronal and photospheric spectra and reveals reddening with distance over the entire corona at all positional angles. It is noted that theRCIdistribution for the corona on July 11, 1991, and that earlier obtained for the corona on March 29, 2006, are the first confirmations of theoretical calculations on the shift of the continuum spectrum to the red side due to electron fluxes propagating from the Sun throughout the corona.