The Observational Features and Theoretical Explanations of the Coronal Transients

The major observational features and theoretical models of the coronal transients are reviewed in the present paper. The coronal transient is the process with a large amount of mass ejection from the solar corona into the interplanetary space. There is 5×10¹⁵ grams of mass which is driven into the heliosphere with the typical velocity 500 km/sec in the period of 10³ seconds. There are close connections between the coronal transients and the events of solar flare and eruptive prominence. As a recent discovered phenomenon of the solar activity, many theoretical explanations have suggested for the coronal transient processes in the recent years. One approach is the numerical similarity, in which the coronal transient is driven by the pulsation of one of the thermodynamical quantities or the magnetic pressure at the low corona. Several analytical models consider that the loop transient is driven by the Lorentz force in the loop, or by the magnetic pressure outside the loop, or the MHD buoyancy force of the loop. By consideration of the connection between the transient and the solar flare and eruptive prominence, piston driving model suggest that the coronal transient is driven by the ejection of the dense plasma. More researches should be completed in both the observations snd the theories in future.