Cd. Pike et He. Mason, Rotating transition region features observed with the SOHO coronal diagnostic spectrometer, SOLAR PHYS, 182(2), 1998, pp. 333-348
Strong evidence has been found from SOHO-CDS (Solar and Heliospheric Observ
atory - Coronal Diagnostic Spectrometer) observations to support the hypoth
esis that rotation plays a major role in the dynamics of transition region
features. A comprehensive survey of the CDS daily synoptic rasters has been
carried out to select dynamic events by searching for spectral line shifts
in the O V emission line at 629.73 Angstrom (formed at a temperature of 2.
5 x 10(5) K). Unique CDS observations of a macrospicule were reported by Pi
ke and Harrison (1997), and several more macrospicule-like solar features h
ave now been identified in the polar regions both on the limb and disk. The
se show blue- and red-shifted emission on either side of an axis stretching
above the limb from a footpoint region on the disk. These observations are
interpreted as indicating the presence of a rotating plasma, a sort of sol
ar tornado. In the examples studied, the rotation velocities increase with
height. The implications for coronal heating models are discussed.