Hot channels (HCs), high temperature erupting structures in the lower corona of the Sun, have been proposed as a proxy of magnetic flux ropes (MFRs) since their initial discovery. However, it is difficult to make definitive proof given the fact that
there is no direct measurement of magnetic field in the corona. An alternative way is to use the magnetic field measurement in the solar wind from in-situ instruments. On 2012 July 12, an HC was observed prior to and during a coronal mass ejection (CME) by the AIA high-temperature images. The HC is invisible in the EUVI low-temperature images, which only show the cooler leading front (LF). However, both the LF and an ejecta can be observed in the coronagraphic images. These are consistent with the high temperature and high density of the HC and support that the ejecta is the erupted HC. In the meanwhile, the associated CME shock was identified ahead of the ejecta and the sheath through the COR2 images, and the corresponding ICME was detected by textit{ACE}, showing the shock, sheath and magnetic cloud (MC) sequentially, which agrees with the coronagraphic observations. Further, the MC contained a low-ionization-state center and a high-ionization-state shell, consistent with the pre-existing HC observation and its growth through magnetic reconnection. All of these observations support that the MC detected near the Earth is the counterpart of the erupted HC in the corona for this event. Therefore, our study provides strong observational evidence of the HC as an MFR.
Filament eruptions often lead to coronal mass ejections (CMEs), which can affect critical technological systems in space and on the ground when they interact with the geo-magnetosphere in high speeds. Therefore, it is an important issue to investigat
e the acceleration mechanisms of CMEs in solar/space physics. Based on observations and simulations, the resistive magnetic reconnection and the ideal instability of magnetic flux rope have been proposed to accelerate CMEs. However, it remains elusive whether both of them play a comparable role during a particular eruption. It has been extremely difficult to separate their contributions as they often work in a close time sequence during one fast acceleration phase. Here we report an intriguing filament eruption event, which shows two apparently separated fast acceleration phases and provides us an excellent opportunity to address the issue. Through analyzing the correlations between velocity (acceleration) and soft (hard) X-ray profiles, we suggest that the instability and magnetic reconnection make a major contribution during the first and second fast acceleration phases, respectively. Further, we find that both processes have a comparable contribution to accelerate the filament in this event.
Hot channel (HC) is a high temperature ($sim$10 MK) structure in the inner corona revealed first by Atmospheric Imaging Assembly (AIA) on board textit{Solar Dynamics Observatory}. Eruption of HC is often associated with flare and coronal mass ejectio
n. Previous studies suggest that HC is a good proxy of magnetic flux rope (MFR) in the inner corona, in addition to another well-known MFR candidate, the prominence-cavity structure that is with a normal coronal temperature ($sim$1-2 MK). In this paper, we report a high temperature structure (HTS, $sim$1.5 MK) contained in an interplanetary coronal mass ejection induced by an HC eruption. According to the observations of bidirectional electrons, high temperature and density, strong magnetic field, and its association with the shock, sheath, and plasma pile-up region, we suggest that the HTS is the interplanetary counterpart of the HC. The scale of the measured HTS is around 14 R$_odot$, and it maintained a much higher temperature than the background solar wind even at 1 AU. It is significantly different from the typical magnetic clouds (MCs), which usually have a much lower temperature. Our study suggests that the existence of a corotating interaction region ahead of the HC formed a magnetic container to inhibit the HC expansion and cooling down to a low temperature.
