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arXiv 1101.0641astro-ph.SR
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日冕物质抛射源位置的统计研究:从日冕图看日冕物质抛射

Statistical Study of Coronal Mass Ejection Source Locations: Understanding CMEs Viewed in Coronagraphs

Yuming Wang, Caixia Chen, Bin Gui, Chenglong Shen, Pinzhong Ye, S. Wang

摘要:

如何正确理解白光日冕仪观测到的日冕物质抛射(CME)现象,是太阳物理和空间物理中许多相关研究的关键。本文通过对1997 - 1998年CME星表中1078个LASCO CME的源位置及其与CME视参数的相关性研究,着重讨论了这一问题。通过人工检查这些CME的LASCO和EIT影像,我们发现,除了231个CME的源位置因资料不足而无法确定外,在EIT的视场中,有288个CME的源位置被确定在太阳的正面盘面上,234个CME出现在太阳临边之上,325个CME没有明显的喷发特征。根据CME源位置的统计结果,详细分析了SOHO LASCO和EIT对CME的遗漏率、CME的质量、晕CME的成因和CME在日冕中的偏转等四个物理问题。结果表明:(1)约32%的正面日冕物质抛射不能被SOHO识别;(2)在任何日心距离上,日冕物质抛射的亮度与其速度大致正相关,由亮度推算的日冕物质抛射质量可能被高估;(3)投射效应和剧烈喷发是晕日冕物质抛射的主要原因,尤其是对于临边晕日冕物质抛射,(4)在太阳活动极小期附近,大多数日冕物质抛射向赤道偏转,这些偏转可分为不对称膨胀、非径向抛射和偏转传播三种类型。

英文摘要:

How to properly understand coronal mass ejections (CMEs) viewed in white-light coronagraphs is crucial to many relative researches in solar and space physics. The issue is now particularly addressed in this paper through studying the source locations of all the 1078 LASCO CMEs listed in CDAW CME catalog during 1997 -- 1998 and their correlation with CMEs' apparent parameters. By manually checking LASCO and EIT movies of these CMEs, we find that, except 231 CMEs whose source locations can not be identified due to poor data, there are 288 CMEs with location identified on the front-side solar disk, 234 CMEs appearing above solar limb, and 325 CMEs without evident eruptive signatures in the field of view of EIT. Based on the statistical results of CMEs' source locations, four physical issues, including (1) the missing rate of CMEs by SOHO LASCO and EIT, (2) the mass of CMEs, (3) the causes of halo CMEs and (4) the deflections of CMEs in the corona, are exhaustively analyzed. It is found that (1) about 32% of front-side CMEs can not be recognized by SOHO, (2) the brightness of a CME at any heliocentric distance is roughly positively correlated with its speed, and the CME mass derived from the brightness is probably overestimated, (3) both projection effect and violent eruption are the major causes of halo CMEs, and especially for limb halo CMEs, the latter is the primary one, (4) most CMEs deflected towards equator near the solar minimum, and these deflections can be classified into three types, the asymmetrical expansion, non-radial ejection, and the deflected propagation.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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