The HELCATS Project: Characterising the Evolution of Coronal Mass Ejections Observed During Solar Cycle 24
Abstract:Understanding the evolution of coronal mass ejections (CMEs) is fundamental to advancing our knowledge of energy and mass transport in the solar system, thus also rendering it crucial to space weather and its prediction. The advent of truly wide-angle heliospheric imaging has revolutionised the study of CMEs, by enabling their direct and continuous observation as they propagate from the Sun out to 1 AU and beyond. The recently initiated EU-funded FP7 Heliospheric Cataloguing, Analysis and Technique Service (HELCATS) project combines European expertise in the field of heliospheric imaging, built up over the last decade in particular through lead involvement in NASA’s STEREO mission, with expertise in such areas as solar and coronal imaging as well as the interpretation of in-situ and radio diagnostic measurements of solar wind phenomena.
The goals of HELCATS include the cataloguing of CMEs observed in the heliosphere by the Heliospheric Imager (HI) instruments on the STEREO spacecraft, since their launch in late October 2006 to date, an interval that covers much of the historically weak solar cycle 24. Included in the catalogue will be estimates of the kinematic properties of the imaged CMEs, based on a variety of established, and some more speculative, modelling approaches (geometrical, forward, inverse, magneto-hydrodynamic); these kinematic properties will be verified through comparison with solar disc and coronal imaging observations, as well as through comparison with radio diagnostic and in-situ measurements made at multiple points throughout the heliosphere. We will provide an overview of the HELCATS project, and present initial results that will seek to illuminate the unusual nature of solar cycle 24.