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 6374A [Fex] line using a multislit spectrograph. These spectra have a dispersion of 2.5 A 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 A and 2.4A. A large number of locations have half-widths around 1.3 A 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.