Differential Emission Measure Analysis of Multiple Structural Components of Coronal Mass Ejections in the Inner Corona

Cheng, X.; Zhang, J.; Saar, S. H.; Ding, M. D.

doi:10.1088/0004-637x/761/1/62

Cited by 271 publications

(274 citation statements)

References 71 publications

(101 reference statements)

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“…2 and 5a). These values are consistent with the result from, e.g., Cheng et al (2012). For the CME-EP, we observed hot, moving structures located in the prominence and blob regions, for which the recovered DEMs revealed the temperature range of 0.8-2.5 MK.…”

Section: Discussionsupporting

confidence: 92%

“…Weber et al 2004). The XRT method is available in the SolarSoftWare (SSW) and was successfully implemented for use with the AIA filters (the appendix of Cheng et al (2012)). This is an iterative forward-fitting method where the differences in the fitted and the observed intensities in the six EUV AIA filters used are minimized.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…The DEM analysis of a CME in the early phase of its formation and propagation from the low corona showed the presence of a hot structure in the temperature range 8-14 MK, and a warm (2-4 MK) loop-like front of the eruption (Cheng et al 2012;Hannah & Kontar 2013).…”

Section: Introductionmentioning

confidence: 99%

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Plasma diagnostics in two kinematic classes of CMEs observed by the Atmospheric Imaging Assembly onboard the Solar Dynamic Observatory

et al. 2016

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In order to study the dynamics and thermal properties of two kinematic classes of coronal mass ejections (CMEs) we analyzed two well-observed events in the early stage of their propagation, using multiwavelength observations from the Atmospheric Imaging Assembly (AIA) of the Solar Dynamic Observatory (SDO). For deriving differential emission measure (DEM) profiles and DEM maps of the basic structures of CMEs, we used two methods: the regularized inversion and the iterative forward-fitting approach. For the CME associated with a M2.0 class flare (CME-FL), we identified a hot, moving, blob-like feature which seems to be a candidate for a CME flux rope. Furthermore, an expanding system of loop and coronal dimming was clearly seen in AIA images. For the CME related to an eruptive prominence (CME-EP), we observed an eruptive plasmoid and a failed-eruption of cold plasma. However, we also recognized warm and hot moving signatures that revealed a multi-temperature nature of the eruptive prominence. Our main results are as follows: (a) An analysis of the examples of the two different kinematic classes of CMEs shows that despite the slight variations in the values of speeds and accelerations (CME-FL: v ≈ 174 km s −1 , a ≈ 350 m s −2 ; CME-EP: v ≈ 135 km s −1 , a ≈ 160 m s −2 ) they present the same kinematic behavior; (b) in the field of view of the LASCO coronagraphs these two events have the similar, positive accelerations; (c) for both events we observed an impulsive acceleration phase (IAP); (d) the expanding structures seen in 171 Å, 193 Å, 211 Å in both events move faster than the hotter blobs; (e) the plasmoid core for the CME-FL is hot (8.0-15.8 MK); (f) the expanding blob and the hot structure in the prominence region for the CME-EP event have the similar temperature range (0.8-2.5 MK).

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Section: Discussionsupporting

confidence: 92%

Section: Observations and Data Reductionmentioning

confidence: 99%

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Plasma diagnostics in two kinematic classes of CMEs observed by the Atmospheric Imaging Assembly onboard the Solar Dynamic Observatory

et al. 2016

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“…We carried out DEM reconstructions using the base-difference intensities of the blobs in the six filters and the same program as in Zhang & Ji (2014b). To evaluate the uncertainties of the reconstructed DEM curves, 100 Monte Carlo (MC) simulations were conducted for each inversion (Cheng et al, 2012). The observational parameters are summarized in Table 1.…”

Section: Discussionmentioning

confidence: 99%

Observations of Multiple Blobs in Homologous Solar Coronal Jets in Closed Loop

Zhang

2016

Sol Phys

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Coronal bright points (CBPs) and jets are ubiquitous small-scale brightenings that are often associated with each other. In this paper, we report our multiwavelength observations of two groups of homologous jets. The first group was observed by the Extreme-Ultraviolet Imager (EUVI) aboard the behind Solar TErrestrial RElations Observatory (STEREO) spacecraft in 171Å and 304Å on 2014 September 10, from a location where data from the Solar Dynamic Observatory (SDO) could not observe. The jets (J1−J6) recurred for six times with intervals of 5−15 minutes. They originated from the same primary CBP (BP1) and propagated in the northeast direction along large-scale, closed coronal loops. Two of the jets (J3 and J6) produced sympathetic CBPs (BP2 and BP3) after reaching the remote footpoints of the loops. The time delays between the peak times of BP1 and BP2 (BP3) are 240±75 s (300±75 s). The jets were not coherent. Instead, they were composed of bright and compact blobs. The sizes and apparent velocities of the blobs are 4.5−9 Mm and 140−380 km s −1 , respectively. The arrival times of the multiple blobs in the jets at the far-end of the loops indicate that the sympathetic CBPs are caused by jet flows rather than thermal conduction fronts. The second group was observed by the Atmospheric Imaging Assembly aboard SDO in various wavelengths on 2010 August 3. Similar to the first group, the jets originated from a short-lived bright point (BP) at the boundary of active region 11092 and propagated along a small-scale, closed loop before flowing into the active region. Several tiny blobs with sizes of ∼1.7 Mm and apparent velocity of ∼238 km s −1 were identified in the jets. We carried out the differential emission measure (DEM) inversions to investigate the temperatures of the blobs, finding that the blobs were multithermal with average temperature of 1.8−3.1 MK. The estimated number densities of the blobs were (1.7−2.8)×10 9 cm −3 .

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“…These are obtained using a differential EM (DEM) analysis 23 of six AIA EUV (94 Å, 335 Å, 211 Å, 193 Å, 171 Å, and 131 Å) channels (see Fig. 4 and Supplementary Movie 3).…”

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confidence: 99%

Magnetic reconnection between a solar filament and nearby coronal loops

et al. 2016

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Magnetic reconnection, the rearrangement of magnetic field topology, is a fundamental physical process in magnetized plasma systems all over the universe 1,2 . Its process is difficult to be directly observed. Coronal structures, such as coronal loops and filament spines, often sketch the magnetic field geometry and its changes in the solar corona 3 . Here we show a highly suggestive observation of magnetic reconnection between an erupting solar filament and its nearby coronal loops, resulting in changes in connection of the filament. X-type structures form when the erupting filament encounters the loops. The filament becomes straight, and bright current sheets form at the interfaces with the loops. Many plasmoids appear in these current sheets and propagate bi-directionally. The filament disconnects from the current sheets, which gradually disperse and disappear, reconnects to the loops, and becomes redirected to the loop footpoints. This evolution of the filament and the loops suggests successive magnetic reconnection predicted by theories 1 but rarely detected with such clarity in observations. Our results on the formation, evolution, and disappearance of current sheets, confirm three-dimensional magnetic reconnection theory and have implications for the evolution of dissipation regions and the release of magnetic energy for reconnection in many magnetized plasma systems.Magnetic reconnection 1,2 is considered to play an essential role in the rapid release of the magnetic energy and its conversion to other forms (thermal, kinetic and particle) in magnetized plasma systems (such as accretion disks, solar and stellar coronae, planetary magnetospheres, and laboratory plasmas) throughout the universe. It shows the reconfiguration of the magnetic field geometry. In solar physics, numerous theoretical studies of the magnetic reconnection have been undertaken to explain flares 5 , filament eruptions 6 , et al. In two dimensional (2D) models, reconnection occurs at an X-point where anti-parallel magnetic field lines converge and reconnect 1,5,6 . So far, many observations of magnetic reconnection signatures, e.g., cusp-shaped post-flare loops 7 , loop-top hard X-ray source 3,8 , reconnection inflows 3,9 and outflows 3,10,11 , flare supra-arcades downflows 12,13 , current sheets, and plasmoid ejections 11 , have been reported by using remote sensing data. However, to directly observe the details of magnetic reconnection process is difficult, because of the small spatial scale and the fast temporal evolution of the process.A solar filament is a relatively cool and dense plasma structure in the corona suspended above a magnetic polarity inversion line (PIL), with ends rooted in regions with opposite magnetic polarity. Its spine, a narrow ribbon-like structure through the full filament, consists of horizontal and parallel threads 14 when viewed from above. In the region around a filament, the plasma-beta, i.e., the ratio of thermal to magnetic energy density, is below unity. Because of the high electric conductivity, the...

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Differential Emission Measure Analysis of Multiple Structural Components of Coronal Mass Ejections in the Inner Corona

Cited by 271 publications

References 71 publications

Plasma diagnostics in two kinematic classes of CMEs observed by the Atmospheric Imaging Assembly onboard the Solar Dynamic Observatory

Plasma diagnostics in two kinematic classes of CMEs observed by the Atmospheric Imaging Assembly onboard the Solar Dynamic Observatory

Observations of Multiple Blobs in Homologous Solar Coronal Jets in Closed Loop

Magnetic reconnection between a solar filament and nearby coronal loops

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