Calculating Energy Storage Due to Topological Changes in Emerging Active Region Noaa Ar 11112

Tarr, Lucas A.; Longcope, D. W.

doi:10.1088/0004-637x/749/1/64

Cited by 12 publications

(23 citation statements)

References 29 publications

(51 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this view, new region emergence might trigger flares or CMEs by processes such as breakout reconnection (Antiochos, DeVore, and Klimchuk 1999) between overlying fields in the old flux system and the new flux system, enabling stressed, inner fields in the old flux system to erupt. We believe that more involved analyses of the magnetic interactions between new and old regions using potential fields -such as those undertaken by Longcope et al (2005), Tarr and Longcope (2012), and Tarr et al (2014) -can provide much more information than our interaction-energy approach, although only with greater effort.…”

Section: Discussionmentioning

confidence: 99%

“…(Free energy requires the existence of currents, and in this case, currents would flow on the separatrix between the new and pre-existing flux systems.) Qualitatively, the origin of this energy can be understood in topological terms: it arises from the significant differences in magnetic connections that will generally be present between the actual and potential post-emergence magnetic fields, at least until reconnection between new and preexisting flux systems occurs (e.g., Longcope et al 2005;Tarr and Longcope 2012;Tarr et al 2014). We therefore refer to free energy arising from the emergence of a new region as "topological" free energy, as opposed to the "internal" free energy associated with currents present in the emerging flux system (e.g., McClymont and Fisher 1989;Leka et al 1996) and pre-existing fields.…”

Section: Theorymentioning

confidence: 99%

See 1 more Smart Citation

Active Region Emergence and Remote Flares

Welsch

2016

Sol Phys

View full text Add to dashboard Cite

We study the effect of new emerging solar active regions on the large-scale magnetic environment of existing regions. We first present a theoretical approach to quantify the "interaction energy" between new and pre-existing regions as the difference between (i) the summed magnetic energies of their individual potential fields and (ii) the energy of their superposed potential fields. We expect that this interaction energy can, depending upon the relative arrangements of newly emerged and pre-existing magnetic flux, indicate the existence of "topological" free magnetic energy in the global coronal field that is independent of any "internal" free magnetic energy due to coronal electric currents flowing within the newly emerged and pre-existing flux systems. We then examine the interaction energy in two well-studied cases of flux emergence, but find that the predicted energetic perturbation is relatively small compared to energies released in large solar flares. Next, we present an observational study on the influence of the emergence of new active regions on flare statistics in pre-existing active regions, using NOAA's Solar Region Summary and GOES flare databases. As part of an effort to precisely determine the emergence time of active regions in a large event sample, we find that emergence in about half of these regions exhibits a two-stage behavior, with an initial gradual phase followed by a more rapid phase. Regarding flaring, we find that the emergence of new regions is associated with a significant increase in the occurrence rate of X-and M-class flares in pre-existing regions. This effect tends to be more significant when pre-existing and new emerging active regions are closer. Given the relative weakness of the interaction energy, this effect suggests that perturbations in the large-scale magnetic field, such as topology changes invoked in the "breakout" model of coronal mass ejections, might play a significant role in the occurrence of some flares.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Active Region Emergence and Remote Flares

Welsch

2016

Sol Phys

View full text Add to dashboard Cite

show abstract

“…The basis of the proposed approach in tracking the flux content in evolving magnetic polarities is much simpler than the approach taken by Tarr & Longcope (2012) or Tarr et al (2013) in which the authors track individual polarities (with necessary assumptions on how they are connected). The condition here is that the non-colliding conjugate polarities are adequately isolated from other bipoles so that they can serve as a "calibration" or reference flux level.…”

Section: The Conjugate Flux Deficit Methodsmentioning

confidence: 99%

The Origin of Major Solar Activity: Collisional Shearing between Nonconjugated Polarities of Multiple Bipoles Emerging within Active Regions

Chintzoglou

Zhang

Cheung

et al. 2019

ApJ

108

View full text Add to dashboard Cite

Active Regions (ARs) that exhibit compact Polarity Inversion Lines (PILs) are known to be very flare-productive. However, the physical mechanisms behind this statistical inference have not been demonstrated conclusively. We show that such PILs can occur due to the collision between two emerging flux tubes nested within the same AR. In such multipolar ARs, the flux tubes may emerge simultaneously or sequentially, each initially producing a bipolar magnetic region (BMR) at the surface. During each flux tube's emergence phase, the magnetic polarities can migrate such that opposite polarities belonging to different BMRs collide, resulting in shearing and cancellation of magnetic flux. We name this process "collisional shearing" to emphasize that the shearing and flux cancellation develops due to the collision. Collisional shearing is a process different from the known concept of flux cancellation occurring between polarities of a single bipole, a process that has been commonly used in many numerical models. High spatial and temporal resolution observations from the Solar Dynamics Observatory for two emerging ARs, AR11158 and AR12017, show the continuous cancellation of up to -2 -40% of the unsigned magnetic flux of the smallest BMR, which occurs at the collisional PIL for as long as the collision persists. The flux cancellation is accompanied by a succession of solar flares and CMEs, products of magnetic reconnection along the collisional PIL. Our results suggest that the quantification of magnetic cancellation driven by collisional shearing needs to be taken into consideration in order to improve the prediction of solar energetic events and space weather.

show abstract

“…As the flux concentrations are continuously combining and separating, there is no guarantee that any one pole exists continuously in the many-poles model. Tarr & Longcope (2012) took steps to remedy this by utilizing automated tracking algorithms to gain consistency as the sources evolve in time. Here, at the expense of losing some of the finer topological detail about the two-AR system, we gain continuity by reduction to a quadrupole.…”

Section: Potential Field Modelmentioning

confidence: 99%

Measuring and Modeling the Rate of Separator Reconnection between an Emerging and an Existing Active Region

McCarthy¹,

Longcope²,

Malanushenko³

et al. 2019

ApJ

View full text Add to dashboard Cite

Magnetic reconnection occurs when new flux emerges into the corona and becomes incorporated into the existing coronal field. A new active region (AR) emerging in the vicinity of an existing AR provides a convenient laboratory in which reconnection of this kind can be quantified. We use high time-cadence 171Å data from SDO/AIA focused on new/old active region pair 11147/11149, to quantify reconnection. We identify new loops as brightenings within a strip of pixels between the regions. This strategy is premised on the assumption that the energy brightening a loop originates in magnetic reconnection. We catalog 301 loops observed in the 48-hour time period beginning with the emergence of AR 11149. The rate at which these loops appear between the two ARs is used to calculate the reconnection rate between them. We then fit these loops with magnetic field, solving for each loop's field strength, geometry, and twist (via its proxy, coronal α). We find the rate of newly-brightened flux overestimates the flux which could be undergoing reconnection. This excess can be explained by our finding that the interconnecting region is not at its lowest energy (constant-α) state; the extrapolations exhibit loop-to-loop variation in α. This flux overestimate may result from the slow emergence of AR 11149, allowing time for Taylor relaxation internal to the domain of the reconnected flux to bring the α distribution towards a single value which provides another mechanism for brightening loops after they are first created.

show abstract

Calculating Energy Storage Due to Topological Changes in Emerging Active Region Noaa Ar 11112

Cited by 12 publications

References 29 publications

Active Region Emergence and Remote Flares

Active Region Emergence and Remote Flares

The Origin of Major Solar Activity: Collisional Shearing between Nonconjugated Polarities of Multiple Bipoles Emerging within Active Regions

Measuring and Modeling the Rate of Separator Reconnection between an Emerging and an Existing Active Region

Contact Info

Product

Resources

About