双重电流片和日冕瞬变

当背景磁场在日冕中存在零磁场线时,反向新磁通量的喷发将会产生双重电流片,包括零场区附近的磁场受到挤压而形成的横向电流片和新喷发场、原背景场之间形成的拱形电流片、本文用一对线偶极子来模拟背景场,用一对线磁荷来模拟反向喷发场,讨论了上述双重电流片的形成和演变过程。在电流片形成过程中,物质将向电流片集中。拱形电流片物质主要来自过渡层和光球层,并通过辐射损失进一步冷却,形成低温日珥环;横向电流片的物质则全部来自日冕,从而形成高温日冕环。以上结果可用来解释1984年4月14日观测到的日冕瞬变。

Double Current Sheet and Coronal Transients

A double current sheet occurs as an opposite magnetic flux emerges into a background magnetic field which has a line of zero magnetic field in the corona, ft consists of a transversal sheet, resulting from the squeeze of magnetic field near the zero magnetic field region, and an arched sheet formed in between the newly emerging field and the background. Adapting a pair of line magnetic dipoles to model the background and a pair of line magnetic charges -the newly emerging field, this paper discusses the formation and evolution of the abovemen-tioned double current sheet. Material will concentrate to the sheets during their formation. The material in the arched sheet comes mainly from the transition region and the photosphere and is further cooled by radiation, giving rise to a low-temperature prominence loop. On the other hand, all the material in the transversal sheet comes from the corona and produces a high-temperature coronal loop. The above prediction may be responsible for the coronal transient of April 14, 1984.