Critical Magnetic Field Strengths for Solar Coronal Plumes in Quiet Regions and Coronal Holes?

Avallone, Ellis A.; Tiwari, Sanjiv K.; Panesar, Navdeep K.; Moore, Ronald L.; Winebarger, Amy R.

doi:10.3847/1538-4357/aac82c

Cited by 9 publications

(21 citation statements)

References 34 publications

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“…As described in Wang et al (2016; see also Avallone et al 2018;Qi et al 2019), plume emission brightens as supergranular flows converge, bringing network, intranetwork, and ER fluxes together to form dense clumps; as the underlying flows diverge again and the clumps are dispersed, the Fe IX emission gradually fades. During the convergence phase, which lasts several hours, the entrained minority-polarity flux is brought into increasingly close contact with the open flux that threads the dominant-polarity network elements, driving interchange reconnection at progressively faster rates.…”

Section: Diffuse Plume Emission and The Origin Of Low-frequency Alfvén Wavesmentioning

confidence: 83%

Small-scale Flux Emergence, Coronal Hole Heating, and Flux-tube Expansion: A Hybrid Solar Wind Model

Wang

2020

ApJ

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Extreme-ultraviolet images from the Solar Dynamics Observatory often show loop-like fine structure to be present where no minority-polarity flux is visible in magnetograms, suggesting that the rate of ephemeral region (ER) emergence inside "unipolar" regions has been underestimated. Assuming that this rate is the same inside coronal holes as in the quiet Sun, we show that interchange reconnection between ERs and open field lines gives rise to a solar wind energy flux that exceeds 10 5 erg cm −2 s −1 and that scales as the field strength at the coronal base, consistent with observations. In addition to providing ohmic heating in the low corona, these reconnection events may be a source of Alfvén waves with periods ranging from the granular timescale of ∼10 minutes to the supergranular/plume timescale of many hours, with some of the longer-period waves being reflected and dissipated in the outer corona. The asymptotic wind speed depends on the radial distribution of the heating, which is largely controlled by the rate of flux-tube expansion. Along the rapidly diverging flux tubes associated with slow wind, heating is concentrated well inside the sonic point (1) because the outward conductive heat-flux density and thus the outer coronal temperatures are reduced, and (2) because the net wave energy flux is dissipated at a rate proportional to the local Alfvén speed. In this "hybrid" solar wind model, reconnection heats the lower corona and drives the mass flux, whereas waves impart energy and momentum to the outflow at greater distances.

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Section: Diffuse Plume Emission and The Origin Of Low-frequency Alfvén Wavesmentioning

confidence: 83%

Small-scale Flux Emergence, Coronal Hole Heating, and Flux-tube Expansion: A Hybrid Solar Wind Model

Wang

2020

ApJ

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“…Recent observations of CJs (e.g. Huang et al 2012;Shen et al 2012;Panesar et al 2016b;Sterling et al 2017;Panesar et al 2018) show that flux cancelation is usually the trigger of CJs. Often continuous flux cancelation leads to recurrent/homologous jets (Chandra et al 2015;Panesar et al 2017).…”

Section: Discussionmentioning

confidence: 99%

“…AIA images show some plumes in the coronal hole. We find three jetlet locations/PILs at the base of plumes (Raouafi & Stenborg 2014;Avallone et al 2018) and two jetlet locations/PILs away from plumes (Figure 1). None of these jetlets were covered by the IRIS spectral slit.…”

Section: Introductionmentioning

confidence: 93%

“…Recently, we investigated the triggering mechanism of 10 quiet-region (Panesar et al 2016b(Panesar et al , 2017 and 13 coronal-hole (Panesar et al 2018) CJs and found that CJs in these regions are driven by the eruption of a minifilament, and that the minifilament magnetic field is built (minifilaments exist for periods ranging from 1.5 hr to 2 days prior to their eruption) and triggered by magnetic flux cancelation at the PIL underneath the minifilament. arXiv:1811.04314v1 [astro-ph.SR] 10 Nov 2018…”

Section: Introductionmentioning

confidence: 99%

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IRIS and SDO Observations of Solar Jetlets Resulting from Network-edge Flux Cancelation

Panesar

Sterling

Moore

et al. 2018

ApJL

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Recent observations show that the buildup and triggering of minifilament eruptions that drive coronal jets result from magnetic flux cancelation at the neutral line between merging majority-and minority-polarity magnetic flux patches. We investigate the magnetic setting of ten on-disk small-scale UV/EUV jets (jetlets, smaller than coronal X-ray jets but larger than chromospheric spicules) in a coronal hole by using IRIS UV images and SDO/AIA EUV images and line-of-sight magnetograms from SDO/HMI. We observe recurring jetlets at the edges of magnetic network flux lanes in the coronal hole. From magnetograms co-aligned with the IRIS and AIA images, we find, clearly visible in nine cases, that the jetlets stem from sites of flux cancelation proceeding at an average rate of ∼1.5 × 10 18 Mx hr −1 , and show brightenings at their bases reminiscent of the base brightenings in larger-scale coronal jets. We find that jetlets happen at many locations along the edges of network lanes (not limited to the base of plumes) with average lifetimes of 3 min and speeds of 70km s −1 . The average jetlet-base width (4000 km) is three to four times smaller than for coronal jets (∼18,000 km). Based on these observations of ten obvious jetlets, and our previous observations of larger-scale coronal jets in quiet regions and coronal holes, we infer that flux cancelation is an essential process in the buildup and triggering of jetlets. Our observations suggest that network jetlet eruptions might be small-scale analogs of both larger-scale coronal jets and the still-larger-scale eruptions producing CMEs.

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“…This role is supported by their presence in the cores of bright coronal plumes, again even when no minority-polarity flux is visible in photospheric magnetograms, where they appear to cluster and contribute to coronal-plume energization, heating, and emission when flow convergence causes interchange reconnection between them. Reflecting this dynamic, coronal-plume emission changes on timescales of hours to a day as the supergranular flow field evolves (Wang, Warren, and Muglach, 2016;Avallone et al, 2018;Qi et al, 2019). Previous magnetogram-based studies (e.g.…”

Section: Small-scale Field Evolution? How Turbulent Are Granular Flows? How Dependent Is Quiet-sun Magnetism On the Solar Cycle?mentioning

confidence: 99%

Critical Science Plan for the Daniel K. Inouye Solar Telescope (DKIST)

Rast¹,

González²,

Rubio³

et al. 2021

Sol Phys

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The National Science Foundation’s Daniel K. Inouye Solar Telescope (DKIST) will revolutionize our ability to measure, understand, and model the basic physical processes that control the structure and dynamics of the Sun and its atmosphere. The first-light DKIST images, released publicly on 29 January 2020, only hint at the extraordinary capabilities that will accompany full commissioning of the five facility instruments. With this Critical Science Plan (CSP) we attempt to anticipate some of what those capabilities will enable, providing a snapshot of some of the scientific pursuits that the DKIST hopes to engage as start-of-operations nears. The work builds on the combined contributions of the DKIST Science Working Group (SWG) and CSP Community members, who generously shared their experiences, plans, knowledge, and dreams. Discussion is primarily focused on those issues to which DKIST will uniquely contribute.

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Critical Magnetic Field Strengths for Solar Coronal Plumes in Quiet Regions and Coronal Holes?

Cited by 9 publications

References 34 publications

Small-scale Flux Emergence, Coronal Hole Heating, and Flux-tube Expansion: A Hybrid Solar Wind Model

Small-scale Flux Emergence, Coronal Hole Heating, and Flux-tube Expansion: A Hybrid Solar Wind Model

IRIS and SDO Observations of Solar Jetlets Resulting from Network-edge Flux Cancelation

Critical Science Plan for the Daniel K. Inouye Solar Telescope (DKIST)

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