Imaging of coronal mass ejections by the HELIOS spacecraft

Abstract

The zodiacal light photometers on board the HELIOS spacecraft can be used to form images of coronal mass ejections in the interplanetary medium. Several aspects of these data are unique: they trace coronal mass ejections using Thomson scattering techniques to distances from the Sun greater than 0.5 AU; their perspective from the HELIOS orbits allow information to be gained about the three-dimensional shapes of specific mass ejections viewed both by coronagraphs and HELIOS; the global view afforded by the spacecrafts photometers can image the mass ejection from within and thus relate in situ measurements to the shape of the whole structure. To date, the HELIOS photometers have been used to study coronagraph-observed mass ejections including those which originate at the Sun on 7 May, 24 May, and 27 November, 1979, and 21 May, 18 June, 29 June, and 6 November, 1980. Masses of ejections determined from these data are generally a few times larger than masses determined from SOLWIND coronagraph images.