Eclipse observations of coronal emission lines. I.[FeX]6374 A profiles at the eclipse of 16 February 1980

Abstract

Coronal spectra during the total solar eclipse of February 16, 1980, obtained in the 6374 A (forbidden Fe X) line using a multislit spectrograph are discussed. The dispersion of these spectra is 2.5 A/mm. The observed line profiles from 1.1 to 1.7 earth radii, with a spatial resolution of 10 x 22 sq arcsec, yield half-widths that vary from 0.6 A to 2.4 A. A large number of locations are found to have half-widths around 1.3 A, corresponding to a temperature of 4.6 x 10 to the 6th K. If temperatures of the order of 1.3 x 10 to the 6th K are typical of the regions that emit in the forbidden Fe X, then turbulent velocities of approximately 30 km/s are required for the enhanced line broadening. The line-of-sight velocities measured are found to range from +14 km/sec to -17 km/sec. The velocities of most of the locations are less than + or - 5 km/s. It is concluded that the corona does not show any localized differential mass motion and that it co-rotates with the photospheric layers deeper down.