Remote sensing observations of mass ejections and shocks in interplanetary space

Abstract

It has long been known that disturbances can propagate from Sun to Earth with periods of a few days following large solar flares. These disturbances involve a significant portion of the lower solar corona and the energy of the flare. Several techniques have been used to remotely detect and follow different structures as they propagate outward from the Sun. These techniques include interplanetary scintillation (IPS), kilometric radio and HELIOS photometer observations. Structures in the interplanetary medium can generally be classed as those which propagate outward from the Sun and those which co-rotate with approximately the solar rotation rate. In this review I will concentrate on ejecta and shocks known to be associated with large solar flares observed on the surface of the Sun and their manifestations using various observational techniques. The observational techniques most commonly used are each sensitive to a specific type of structure and more sensitive at one portion of the interplanetary medium than another. Because of the different techniques used, there can often be misinterpretation of the data. In addition, none of the remote sensing observations has complete spatial or temporal coverage. Thus, both the basic physics as well as the spatial and temporal evolution of mass ejections can be confused as these events propagate through the interplanetary medium. Examples of the data related to mass ejections from each of these techniques are shown and interpreted. We expect that future observations will more accurately describe the structures present as their basic physics becomes better known.