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

Abstract

Coronal spectra during the total solar eclipse of 1980 February 16, were obtained in the 6374Å [Fex] line using a multislit spectrograph. These spectra have a dispersion of 2.5 Å mm^-1. The observed line profiles from 1.1 to 1.7 R_⊙ with a spatial resolution of 10 × 22 arcsec², give half-widths that vary between 0.6 Å and 2.4Å. A large number of locations have half-widths around 1.3 Å corresponding to a temperature of 4.6 × 10⁶ K. If temperature of the order of 1.3 × 10⁶ K are typical of the regions that emit [Fex], then turbulent velocities of ~ 30 km s^-1 need to be invoked for the enhanced line broadening. The line-of-sight velocities measured range between +14 km s^-1 to -17 km s^-1. Most of the locations have velocities less than ±5 km s^-1. From these observations we conclude that corona does not show any localized differential mass motion and that it co-rotates with the photospheric layers deeper down.