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arXiv 0903.2776astro-ph.SR
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与临晕日冕物质抛射有关的大磁暴

Large Geomagnetic Storms Associated with Limb Halo Coronal Mass Ejections

Nat Gopalswamy, Seiji Yashiro, Hong Xie, Sachiko Akiyama, Pertti Makela

摘要:

由于太阳和日光层观测站飞行任务所载的大角度和光谱日冕物质抛射仪具有高动态范围和扩大的视场,在第23个太阳活动周观测到了数百次晕日冕物质抛射。超过三分之二的日冕物质抛射起源于太阳正面,被发现是地球效应的(Dst < -50 nT)。已经发现晕CME的开始和随后的地磁暴的峰值之间的延迟时间取决于太阳源位置(Gopalswamy等人,2007年)。特别是,临晕日冕物质抛射(源经度> 45度)的延迟时间平均要短20%。认为由临晕引起的磁暴是由于行星际日冕物质抛射(ICME)的鞘层部分引起的,因此可以解释较短的延迟时间。我们证实了这一建议,通过检查鞘和喷出物部分ICME风和ACE数据,对应的肢体晕。详细的检查表明,三对肢体晕是相互作用的事件。五个盘晕之后的磁暴实际上是由其他盘晕产生的。风暴之后的四个孤立的边缘晕和那些与相互作用的边缘晕,都是由于鞘的ICME部分。

英文摘要:

Solar cycle 23 witnessed the observation of hundreds of halo coronal mass ejections (CMEs), thanks to the high dynamic range and extended field of view of the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission. More than two thirds of halo CMEs originating on the front side of the Sun have been found to be geoeffective (Dst =< -50 nT). The delay time between the onset of halo CMEs and the peak of ensuing geomagnetic storms has been found to depend on the solar source location (Gopalswamy et al., 2007). In particular, limb halo CMEs (source longitude > 45deg) have a 20% shorter delay time on the average. It was suggested that the geomagnetic storms due to limb halos must be due to the sheath portion of the interplanetary CMEs (ICMEs) so that the shorter delay time can be accounted for. We confirm this suggestion by examining the sheath and ejecta portions of ICMEs from Wind and ACE data that correspond to the limb halos. Detailed examination showed that three pairs of limb halos were interacting events. Geomagnetic storms following five limb halos were actually produced by other disk halos. The storms followed by four isolated limb halos and the ones associated with interacting limb halos, were all due to the sheath portions of ICMEs.

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