A Full Study on the Sun–earth Connection of an Earth-Directed Cme Magnetic Flux Rope

Vemareddy, P.; Mishra, Wageesh

doi:10.1088/0004-637x/814/1/59

Cited by 26 publications

(38 citation statements)

References 109 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The net flux in these regions is plotted in the bottom panels, which show continuous decreasing evolution. We thus suggest from these observational evidences that the persistent slow shearing and converging motions about the PIL played prime role in the cancellation of fluxes leading to the initiation and eruption of the sigmoid configuration (Green & Kliem 2009;Green et al 2011;Savcheva et al 2012;Vemareddy & Mishra 2015;Vemareddy 2017b).…”

Section: Evolution Of Photospheric Magnetic Parametersmentioning

confidence: 70%

Formation and Eruption of Sigmoidal Structure from a Weak Field Region of NOAA 11942

Vasantharaju

Vemareddy

Ravindra

et al. 2019

ApJ

Self Cite

View full text Add to dashboard Cite

Using observations from Solar Dynamics Observatory, we studied an interesting example of a sigmoid formation and eruption from small-scale flux canceling regions of active region (AR) 11942. Analysis of HMI and AIA observations infer that initially the AR is compact and bipolar in nature, evolved to sheared configuration consisting of inverse J-shaped loops hosting a filament channel over a couple of days. By tracking the photospheric magnetic features, shearing and converging motions are observed to play a prime role in the development of S-shaped loops and further flux cancellation leads to tethercutting reconnection of J-loops. This phase is co-temporal with the filament rise motion followed by sigmoid eruption at 21:32 UT on January 6. The flux rope rises in phases of slow (v avg = 26 km s −1 ) and fast (a avg = 55 ms −2 ) rise motion categorizing the CME as slow with an associated weak C1.0 class X-ray flare. The flare ribbon separation velocity peaks at around peak time of the flare at which maximum reconnection rate (2.14 Vcm −1 ) occurs. Further, the EUV light-curves of 131, 171Å have delayed peaks of 130 minutes compared to 94Å and is explained by differential emission measure. Our analysis suggests that the energy release is proceeded in a much long time duration, manifesting the onset of filament rise and eventual eruption driven by converging and canceling flux in the photosphere. Unlike strong eruption events, the observed slow CME and weak flare are indications of slow runway tether-cutting reconnection where most of the sheared arcade is relaxed during the extended post phase of the eruption.

show abstract

Section: Evolution Of Photospheric Magnetic Parametersmentioning

confidence: 70%

Formation and Eruption of Sigmoidal Structure from a Weak Field Region of NOAA 11942

Vasantharaju

Vemareddy

Ravindra

et al. 2019

ApJ

Self Cite

View full text Add to dashboard Cite

show abstract

“…They occur in a time scale of less than an hour or so, far less than that of build up of the sigmoid. From similar studies of ARs (Green & Kliem 2009;Green et al 2011;Vemareddy & Mishra 2015), the mechanism that best explains the eruptions in our AR 12371 is tether cutting model (Moore & Labonte 1980;Moore et al 2001;Moore & Sterling 2006). In this model, the pre-eruptive sigmoid consists of a central shear core about PIL and two oppositely curved loops as magnetic elbows.…”

Section: Initiation and Triggering Mechanismmentioning

confidence: 82%

Successive Homologous Coronal Mass Ejections Driven by Shearing and Converging Motions in Solar Active Region NOAA 12371

Vemareddy

2017

ApJ

Self Cite

View full text Add to dashboard Cite

We study magnetic field evolution in AR12371 relating its successive eruptive nature. During the disk transit of seven days, the AR launched four sequential fast coronal mass ejections (CMEs) associated with long duration M-class flares. Morphological study delineates a pre-eruptive coronal sigmoid structure above the polarity inversion line (PIL) similar to Moore et al study. Velocity field derived from tracked magnetograms indicates persistent shear and converging motions of polarity regions about the PIL. While these shear motions continue, the crossed arms of two sigmoid elbows are being brought to interaction by converging motions at the middle of PIL, initiating tether-cutting reconnection of field lines and the onset of CME explosion. The successive CMEs are explained by a cyclic process of magnetic energy storage and release terming "sigmoid-to-arcade-to-sigmoid" transformation driven by photospheric flux motions. Further, the continued shear motions inject helicity flux of dominant negative sign, which contributes to core field twist and its energy by building a twisted flux rope (FR). After a limiting value, the excess coronal helicity is expelled by bodily ejection of the FR initiated by some instability as realized by intermittent CMEs. This AR is in contrast to the confined AR12192 with predominant negative signed larger helicity flux but very weaker (-0.02turns) normalised coronal helicity content. While predominant signed helicity flux is a requirement for CME eruption, our study suggests the magnetic flux normalized helicity flux as a necessary condition accommodating the role of background flux and appeals a further study of large sample of ARs.

show abstract

“…Therefore, we are able to determine all the near-Sun FR properties of the CME in order to use those as realistic inputs for INFROS model. The source location of the M6.6 flare that occurred in AR 11719, was associated with a pre-eruptive sigmoidal structure (Vemareddy & Mishra 2015;Joshi et al 2017). Panel (a) of Figure 5 shows the highly skewed pre-flare sigmoid observed in EUV images of AIA passbands (94 A, 335Å and 193Å).…”

Section: Infros Model Validation: a Test Casementioning

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

View full text Add to dashboard Cite

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.

show abstract

A Full Study on the Sun–earth Connection of an Earth-Directed Cme Magnetic Flux Rope

Cited by 26 publications

References 109 publications

Formation and Eruption of Sigmoidal Structure from a Weak Field Region of NOAA 11942

Formation and Eruption of Sigmoidal Structure from a Weak Field Region of NOAA 11942

Successive Homologous Coronal Mass Ejections Driven by Shearing and Converging Motions in Solar Active Region NOAA 12371

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

Contact Info

Product

Resources

About