Statistical Study of the Magnetic Field Orientation in Solar Filaments

Hanaoka, Yoichiro; Sakurai, Takashi

doi:10.3847/1538-4357/aa9cf1

Cited by 25 publications

(19 citation statements)

References 43 publications

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“…Spectropolarimetric observations using the He I 1083.0 nm line can provide a very useful diagnosis of magnetic field and flows in filaments and prominences. Hanaoka and Sakurai (2017) used data from full-disk 1083.0 spectropolarimetry to obtain a statistic evaluation of magnetic field orientation in filaments. Sasso et al (2014) analyzed the 1083.0 spectropolarimetric observation of an active region filament activated by a flare and found evidence of a coronal flux rope.…”

Section: Discussion and Future Prospectivementioning

confidence: 99%

Signatures of Magnetic Flux Ropes in the Low Solar Atmosphere Observed in High Resolution

Wang

Liu

2019

Front. Astron. Space Sci.

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Magnetic flux ropes (MFRs) are important physical features closely related to solar eruptive activities with potential space weather consequences. Studying MFRs in the low solar atmosphere can shed light on their origin and subsequent magnetic structural evolution. In recent years, observations of solar photosphere and chromosphere reached a spatial resolution of 0.1 to 0.2 arcsec with the operation of meter class ground-based telescopes, such as the 1.6 m Goode Solar Telescope at Big Bear Solar Observatory and the 1 m New Vacuum Solar Telescope at Yunnan Observatory. The obtained chromospheric Hα filtergrams with the highest resolution thus far have revealed detailed properties of MFRs before and during eruptions, and the observed pre-eruption structures of MFRs are well consistent with those demonstrated by non-linear force-free field extrapolations. There is also evidence that MFRs may exist in the photosphere. The magnetic channel structure, with multiple polarity inversions and only discernible in high-resolution magnetograph observations, may be a signature of photospheric MFRs. These MFRs are likely formed below the surface due to motions in the convection zone and appear in the photosphere through flux emergence. Triggering of some solar eruptions is associated with an enhancing twist in the low-atmospheric MFRs.

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Section: Discussion and Future Prospectivementioning

confidence: 99%

Signatures of Magnetic Flux Ropes in the Low Solar Atmosphere Observed in High Resolution

Wang

Liu

2019

Front. Astron. Space Sci.

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“…Merenda et al (2007) studied the orientation of the magnetic field of a solar filament near disk center, and found that the inclination of the magnetic field is horizontal in the central part of the filament and changes along the filament axis, and its azimuth changes along the filament as well. Hanaoka, & Sakurai (2017) statistically studied the orientation of the magnetic field of filaments and confirmed their hemispheric pattern of chirality.…”

Section: Introductionmentioning

confidence: 86%

Magnetic Structure of an Erupting Filament

Wang

Jenkins

Pillet

et al. 2020

ApJ

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The full 3-D vector magnetic field of a solar filament prior to eruption is presented. The filament was observed with the Facility Infrared Spectropolarimeter at the Dunn Solar Telescope in the chromospheric He i line at 10830Å on May 29 and 30, 2017. We inverted the spectropolarimetric observations with the HAnle and ZEeman Light (HAZEL) code to obtain the chromospheric magnetic field. A bimodal distribution of field strength was found in or near the filament. The average field strength was 24 Gauss, but prior to the eruption we find the 90th percentile of field strength was 435 Gauss for the observations on May 29. The field inclination was about 67 degree from the solar vertical. The field azimuth made an angle of about 47 to 65 degree to the spine axis. The results suggest an inverse configuration indicative of a flux rope topology. He i intensity threads were found to be co-aligned with the magnetic field direction. The filament had a sinistral configuration as expected for the southern hemisphere. The filament was stable on May 29, 2017 and started to rise during two observations on May 30, before erupting and causing a minor coronal mass ejection. There was no obvious change of the magnetic topology during the eruption process. Such information on the magnetic topology of erupting filaments could improve the prediction of the geoeffectiveness of solar storms.

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“…However, the statistical studies by Liu et al (2014) show that the hemispheric rule is followed only in 60% of cases. Therefore, in order to confirm the chirality and the axial orientation of the FRs we use other signatures such as pre-flare sigmoidal structures (Rust & Kumar 1996), J-shaped flare ribbons (Janvier et al 2014), coronal dimmings (Webb et al 2000;Thompson et al 2000;Gopalswamy et al 2018c), coronal cells (Sheeley et al 2013) or filament orientations (Hanaoka & Sakurai 2017). Analyzing the locations of the two core dimming regions or the two ends of the pre-flare sigmoidal structure, one can identify the locations of the two foot points of the FR.…”

Section: Direction Of the Axial Magnetic Field And The Sign Of Helicitymentioning

confidence: 99%

An Observationally Constrained Analytical Model for Predicting the Magnetic Field Vectors of Interplanetary Coronal Mass Ejections at 1 au

Sarkar

Gopalswamy

Srivastava

2020

ApJ

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We report on an observationally constrained analytical model, the INterplanetary Flux ROpe Simulator (INFROS), for predicting the magnetic-field vectors of coronal mass ejections (CMEs) in the interplanetary medium. The main architecture of INFROS involves using the near-Sun flux rope properties obtained from the observational parameters that are evolved through the model in order to estimate the magnetic field vectors of interplanetary CMEs (ICMEs) at any heliocentric distance. We have formulated a new approach in INFROS to incorporate the expanding nature and the time-varying axial magnetic field-strength of the flux rope during its passage over the spacecraft. As a proof of concept, we present the case study of an Earth-impacting CME which occurred on 2013 April 11. Using the near-Sun properties of the CME flux rope, we have estimated the magnetic vectors of the ICME as intersected by the spacecraft at 1 AU. The predicted magnetic field profiles of the ICME show good agreement with those observed by the in-situ spacecraft. Importantly, the maximum strength (10.5 ± 2.5 nT) of the southward component of the magnetic field (Bz) obtained from the model prediction, is in agreement with the observed value (11 nT). Although our model does not include the prediction of the ICME plasma parameters, as a first order approximation it shows promising results in forecasting of Bz in near real time which is critical for predicting the severity of the associated geomagnetic storms. This could prove to be a simple space-weather forecasting tool compared to the time-consuming and computationally expensive MHD models.

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Statistical Study of the Magnetic Field Orientation in Solar Filaments

Cited by 25 publications

References 43 publications

Signatures of Magnetic Flux Ropes in the Low Solar Atmosphere Observed in High Resolution

Signatures of Magnetic Flux Ropes in the Low Solar Atmosphere Observed in High Resolution

Magnetic Structure of an Erupting Filament

An Observationally Constrained Analytical Model for Predicting the Magnetic Field Vectors of Interplanetary Coronal Mass Ejections at 1 au

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