磁通量喷发的大气响应Ⅱ.太阳附近的慢激波  

Solar Atmospheric Responses to Magnetic Flux Eruptions II. Slow Shocks Near the Sun

作　　者：胡友秋[1] 郑惠南[1] 

机构地区：[1]中国科学技术大学地球和空间科学系

出　　处：《天体物理学报》1991年第2期188-193,共6页

基　　金：国家自然科学基金

摘　　要：日冕物质喷射的观测速度常低于阿尔芬波速的估计值而高于背景日冕声速,这说明日冕物质喷射可能在日冕中形成慢激波。本文取带赤道电流片的冕流结构作为背景,用冕流底部的磁通量喷发作为驱动机制,对日冕物质喷射触发的慢激波进行数值模拟。结果表明,电流片对激波结构有着重要影响。慢激波只出现在电流片的外部,在电流片中逐渐过渡为快激波,慢激波前方的背景磁场在快磁声波的作用下显著偏转,背景密度下降超过10％。慢激波的纬度范围有限,从电流片的外沿大约延伸到±20°,且具有凹向上方的外形。The observed speeds of coronal mass ejections are often below the estimated Alfven speed but above the sound speed for the background solar corona. This circumstance suggests that coronal mass ejections may form slow shocks in the corona. This paper presents a numerical simulation of the slow shock triggered by a coronal mass ejection, taking a coronal streamer with an equatorial electric current sheet as the background as well as a magnetic flux eruption at the base of the coronal streamer as the driving mechanism. The results show that the current sheet has a significant inf luence on the shock wave structure. The slow shock occurs only on the outside of the current sheet and is gradually being transformed into a fast shock within the sheet. A fast magnetosonic wave exists in front of the slow shock, and it deflects the background magnetic field substantially and reduces the background density by more than 10% over there. The slow shock has a limited latitudinal extent and a concave-upward shape, stretching from the external edge of the current sheet to ±20°.

关 键 词：太阳 磁场 慢激波 

分 类 号：P182.62[天文地球—天文学]