Multiwavelength and Dual-perspective Observations of Eruption and Untwisting of Two Homologous Magnetic Flux Ropes

Abstract In this paper, we present a detailed morphological, kinematic, and thermal analysis of two homologous magnetic flux ropes (MFRs) from NOAA 11515 on 2012 July 8–9. The study is based on multiwavelength and dual-perspective imaging observations from the Solar Dynamics Observatory and the Solar Terrestrial Relations Observatory Ahead spacecraft, which can reveal the structure and evolution of the two MFRs. We find that both of the MFRs show up in multiple passbands and their emissions mainly consist of a cold component peaking at a temperature of ∼0.4–0.6 MK and a hot component peaking at ∼7–8 MK. The two MFRs exhibit erupting, expanding, and untwisting motions that manifest distinctive features from two different viewpoints. Their evolution can be divided into two stages—a fast-eruption stage with speeds of about 105–125 km s−1 for MFR-1 and 50–65 km s−1 for MFR-2—and a slow-expansion (or untwisting) stage with speeds of about 10–35 km s−1 for MFR-1 and 10–30 km s−1 for MFR-2 in the plane of the sky. We also find that during the two-stage evolution, the high-temperature features mainly appear in the interface region between MFRs and ambient magnetic structures and also in the center of MFRs, which suggests that some heating processes take place in such places as magnetic reconnection and plasma compression. These observational results indicate that the eruption and untwisting processes of MFRs are coupled with the heating process, among which an energy conversion exists.

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When do solar erupting hot magnetic flux ropes form?

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038832 ◽

2020 ◽

Vol 642 ◽

pp. A109 ◽

Cited By ~ 1

Author(s):

A. Nindos ◽

S. Patsourakos ◽

A. Vourlidas ◽

X. Cheng ◽

J. Zhang

Keyword(s):

Magnetic Flux ◽

Flux Rope ◽

Flare Activity ◽

Solar Dynamics Observatory ◽

Magnetic Flux Ropes ◽

Morphological Criteria ◽

Flux Ropes ◽

Solar Eruptions ◽

Solar Dynamics ◽

Mass Ejection

Aims. We investigate the formation times of eruptive magnetic flux ropes relative to the onset of solar eruptions, which is important for constraining models of coronal mass ejection (CME) initiation. Methods. We inspected uninterrupted sequences of 131 Å images that spanned more than eight hours and were obtained by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to identify the formation times of hot flux ropes that erupted in CMEs from locations close to the limb. The appearance of the flux ropes as well as their evolution toward eruptions were determined using morphological criteria. Results. Two-thirds (20/30) of the flux ropes were formed well before the onset of the eruption (from 51 min to more than eight hours), and their formation was associated with the occurrence of a confined flare. We also found four events with preexisting hot flux ropes whose formations occurred a matter of minutes (from three to 39) prior to the eruptions without any association with distinct confined flare activity. Six flux ropes were formed once the eruptions were underway. However, in three of them, prominence material could be seen in 131 Å images, which may indicate the presence of preexisting flux ropes that were not hot. The formation patterns of the last three groups of hot flux ropes did not show significant differences. For the whole population of events, the mean and median values of the time difference between the onset of the eruptive flare and the appearance of the hot flux rope were 151 and 98 min, respectively. Conclusions. Our results provide, on average, indirect support for CME models that involve preexisting flux ropes; on the other hand, for a third of the events, models in which the ejected flux rope is formed during the eruption appear more appropriate.

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Magnetic Flux Ropes of Venus: A Paradigm for Helical Magnetic Structures in Astrophysical Systems

Unstable Current Systems and Plasma Instabilities in Astrophysics ◽

10.1007/978-94-009-6520-1_4 ◽

1985 ◽

pp. 43-46 ◽

Cited By ~ 1

Author(s):

R. C. Elphic

Keyword(s):

Magnetic Flux ◽

Magnetic Structures ◽

Magnetic Flux Ropes ◽

Flux Ropes

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Statistical Study of Small-Scale Interplanetary Magnetic Flux Ropes in the Vicinity of the Heliospheric Current Sheet

Frontiers in Physics ◽

10.3389/fphy.2021.745152 ◽

2021 ◽

Vol 9 ◽

Author(s):

Qiang Liu ◽

Yan Zhao ◽

Guoqing Zhao

Keyword(s):

Magnetic Flux ◽

Current Sheet ◽

Interplanetary Space ◽

Axial Direction ◽

Heliospheric Current Sheet ◽

Normal Direction ◽

Small Scale ◽

Magnetic Structures ◽

Magnetic Flux Ropes ◽

Flux Ropes

The small-scale interplanetary magnetic flux ropes (SIMFRs) are common magnetic structures in the interplanetary space, yet their origination is still an open question. In this article, we surveyed 63 SIMFRs found within 6-day window around the heliospheric current sheet (HCS) and investigated their axial direction, as well as the local normal direction of the HCS. Results showed that the majority (48/63) of the SIMFRs were quasi-parallel to the associated HCS (i.e., the axial direction of SIMFRs was quasi-perpendicular to the normal direction of the associated HCS). They also showed that the SIMFRs quasi-parallel to the associated HCS statistically had shorter duration than the cases quasi-perpendicular. The results indicate that most of these SIMFRs may be generated in the nearby HCSs.

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Magnetic Flux Ropes of Venus: A Paradigm for Helical Magnetic Structures in Astrophysical Systems

Symposium - International Astronomical Union ◽

10.1017/s0074180900075495 ◽

1985 ◽

Vol 107 ◽

pp. 43-46

Author(s):

R. C. Elphic

Keyword(s):

Magnetic Flux ◽

Small Scale ◽

Magnetic Structures ◽

Magnetic Flux Ropes ◽

Kink Mode ◽

Cylindrically Symmetric ◽

Direct Measurements ◽

Flux Ropes ◽

Symmetric Structures

The magnetic flux ropes of Venus are small scale (ion gyroradius) cylindrically symmetric structures observed in situ by the Pioneer Venus orbiter in the largely magnetic field-free ionosphere of the planet. They are so named because of their helical magnetic structure, which in turn is due to primarily field-aligned currents within the rope. Empirical models can be used to examine the current structure in detail, and these models indicate that flux ropes may be unstable to the helical kink mode. Statistics of rope distribution and orientation also support this instability picture. The results of investigations into the direct measurements of Venus flux ropes may be relevant to certain astrophysical phenomena that must be observed remotely.

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