Radial velocity discriminated coronal photometric measurements at the July 11, 1991 total eclipse

The results from a set of 12 solar corona radial velocity measurements in the 400–440 nm spectral band during the total solar eclipse of July 11, 1991 are reported. The measurements show that the orbital motion of the F-corona material near the sun in the ecliptic plane is consistent with Keplerian motion and predominantly, but not exclusively, prograde, as is usually assumed. This work demonstrates a method of using the measured radial velocities to sort out the relative amounts of K-corona, near-earth F-corona, near-solar F-corona, and scattered light in each measurement for each observation point W and E of the sun between 2.5Ro(solar radii) and 5Ro along the celestial equator and at three points north of the sun. The near-solar F-corona component is quite weak, contributing only 7–14% of the total signal in each case. The stronger diffraction component from near-earth F-corona is estimated to have been produced by particles with radii of about 11μ. In contrast, the scattered light component appears as strong zero-velocity features dominating all the measurements. The measurements W and E of the sun and near the ecliptic plane also show evidence of a red-shift velocity of at least 330 km s−1, suggestive of a high-speed dust outflow from the sun.