Journal
SOLAR PHYSICS
Volume 244, Issue 1-2, Pages 115-137Publisher
SPRINGER
DOI: 10.1007/s11207-007-9034-2
Keywords
coronal mass ejection : interplanetary; magnetic fields : interplanetary; magnetic reconnection : observational signatures; solar wind : disturbances
Categories
Ask authors/readers for more resources
The solar wind conditions at one astronomical unit (AU) can be strongly disturbed by interplanetary coronal mass ejections (ICMEs). A subset, called magnetic clouds (MCs), is formed by twisted flux ropes that transport an important amount of magnetic flux and helicity, which is released in CMEs. At 1 AU from the Sun, the magnetic structure of MCs is generally modeled by neglecting their expansion during the spacecraft crossing. However, in some cases, MCs present a significant expansion. We present here an analysis of the huge and significantly expanding MC observed by the Wind spacecraft during 9-10 November 2004. This MC was embedded in an ICME. After determining an approximate orientation for the flux rope using the minimum variance method, we obtain a precise orientation of the cloud axis by relating its front and rear magnetic discontinuities using a direct method. This method takes into account the conservation of the azimuthal magnetic flux between the inbound and outbound branches and is valid for a finite impact parameter (i.e., not necessarily a small distance between the spacecraft trajectory and the cloud axis). The MC is also studied using dynamic models with isotropic expansion. We have found (6.2 +/- 1.5)x10(20) Mx for the axial flux and (78 +/- 18)x10(20) Mx for the azimuthal flux. Moreover, using the direct method, we find that the ICME is formed by a flux rope (MC) followed by an extended coherent magnetic region. These observations are interpreted by considering the existence of a previously larger flux rope, which partially reconnected with its environment in the front. We estimate that the reconnection process started close to the Sun. These findings imply that the ejected flux rope is progressively peeled by reconnection and transformed to the observed ICME (with a remnant flux rope in the front part).
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available