Interplanetary flux rope ejected from an X-ray bright point. The smallest magnetic cloud source-region ever observed
Interplanetary flux rope ejected from an X-ray bright point. The smallest magnetic cloud source-region ever observed
复制标题
DOI：
10.1051/0004-6361:20041079
复制
发表时间：
2005-05
影响因子：
6.5
通讯作者：
C. Mandrini;S. Pohjolainen;S. Dasso;L. Green;P. Démoulin;L. Driel-Gesztelyi;C. Copperwheat;C. Foley
中科院分区：
文献类型：
--
作者：
C. Mandrini;S. Pohjolainen;S. Dasso;L. Green;P. Démoulin;L. Driel-Gesztelyi;C. Copperwheat;C. Foley
使用多仪器和多波长观测（SOHO/MDI和EIT，TRACE和Yohkoh/SXT），以及计算一个微小的双极的日冕磁场结合风的模拟原位数据，我们提供了有史以来观察到的最小事件的证据，将S形喷发与行星际磁云（MC）联系起来。在非常接近太阳盘中心的地方观察到的微小双极，其通量比经典的活动区（AR）少100倍。在日冕中，它具有S形结构，主要在EUV中观察到，并且我们在建模磁场中发现了非常高的非电势水平，比我们在任何AR中发现的高10倍。从1998年5月11日起，直到它消失，S形肌经历了三次强烈的脉冲事件。这些事件中最大的一个具有扩展的EUV变暗和尖点。4.5天后，风号探测器探测到了迄今为止发现的最小的MC之一（轴向分量的磁通量比平均MC的磁通量小100倍）。这最后一次喷发和行星际磁云之间的联系得到了几个证据的支持：良好的时间，相同的日冕环和MC方向，相同的磁场方向和日冕环和MC中的磁螺旋度符号。我们进一步量化这种联系，通过估计磁通量（在变暗区域和MC中测量）和磁螺旋度（前到事件发生后的太阳日冕和MC的螺旋度内容的变化）。在不确定性的范围内，磁通量和螺旋度都有合理的一致性，这进一步证明了它们之间的联系。这些观测结果表明，微小磁通绳的喷射确实是可能的，并对CME模型提出了新的限制。
Using multi-instrument and multi-wavelength observations (SOHO/MDI and EIT, TRACE and Yohkoh/SXT), as well as computing the coronal magnetic field of a tiny bipole combined with modelling of Wind in situ data, we provide evidences for the smallest event ever observed which links a sigmoid eruption to an interplanetary magnetic cloud (MC). The tiny bipole, which was observed very close to the solar disc centre, had a factor one hundred less flux than a classical active region (AR). In the corona it had a sigmoidal structure, observed mainly in EUV, and we found a very high level of non- potentiality in the modelled magnetic field, 10 times higher than we have ever found in any AR. From May 11, 1998, and until its disappearance, the sigmoid underwent three intense impulsive events. The largest of these events had extended EUV dimmings and a cusp. The Wind spacecraft detected 4.5 days later one of the smallest MC ever identified (about a factor one hundred times less magnetic flux in the axial component than that of an average MC). The link between this last eruption and the interplanetary magnetic cloud is supported by several pieces of evidence: good timing, same coronal loop and MC orientation, same magnetic field direction and magnetic helicity sign in the coronal loops and in the MC. We further quantify this link by estimating the magnetic flux (measured in the dimming regions and in the MC) and the magnetic helicity (pre- to post-event change in the solar corona and helicity content of the MC). Within the uncertainties, both magnetic fluxes and helicities are in reasonable agreement, which brings further evidences of their link. These observations show that the ejections of tiny magnetic flux ropes are indeed possible and put new constraints on CME models.