Extended statistical analysis of emerging solar active regions

Kutsenko, A. S.; Abramenko, V. I.; Pevtsov, Alexei A.

doi:10.1093/mnras/stz308

Cited by 19 publications

(30 citation statements)

References 75 publications

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“…The average force-free parameter is almost positive during the emergence of the active region, which does not follow the hemisphere rule. The magnitude of the average force-free parameter is the order of ∼ 10 −8 m −1 , which is consistent with results from previous studies (Wang & Abramenko 2000;Kutsenko et al 2019). It rises up to 6 × 10 −8 m −1 at 10:00 UT on Aug 24.…”

Section: Magnetic Propertiessupporting

confidence: 92%

“…Their power-law index is about 0.36 which is a similar value to ours. It should be noted that our study just focuses on the evolution of one active region, while the statistical study of Kutsenko et al (2019) includes the properties of many different emerging active regions. Therefore, the dependence of polarities separation on magnetic flux is a fundamental relationship -either in the evolution of one emerging active region or between different emerging active regions.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…A calculable quantity (α z = J z (x,y) y) ) is a commonly used proxy of the twist at the photospheric level (Pevtsov et al 1994). Here, we calculate an averaged fluxweighted force-free parameter α over the whole AR in the photosphere, based on the following equation (Hagino, & Sakurai 2004;Kutsenko et al 2019):…”

Section: Pole Separation and Tilt Anglementioning

confidence: 99%

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Naked emergence of an anti-Hale active region I. Overall evolution and magnetic properties

Wang,

Yan,

Kong

et al. 2021

Preprint

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Context.Aims. In order to understand the emergence of the active region, we investigate the emerging process and magnetic properties of a naked anti-Hale active region during the period between August 24 to 25, 2018. Methods. Using the data from Helioseismic and Magnetic Imager on board the Soar Dynamic Observatory and the New Vacuum Solar Telescope, we calculated different evolving parameters (such as pole separation, tilt angle) and magnetic parameters (such as vertical electric current, force-free parameter, relative magnetic helicity) during the emergence of the active region. With these calculated parameters and some reasonable assumptions, we use two different methods to estimate the twist of the active region. Results. The magnetic flux and pole separation continue increasing while the tilt angle exhibits a decreasing pattern during the emergence of the active region. The increase of the pole separation is mainly contributed as a result of the enhancement in the longitude direction. A power-law relationship between pole separation and total flux is found during the emergence of the active region. On the other hand, it is found that both the positive and negative electric currents increased equivalently and the average flux-weighted force-free parameter α remains almost consistently positive, on the order of ∼ 10 −8 m −1 . The relative magnetic helicity is mainly contributed by the shear term, while the relative magnetic helicity injection flux of the shear term changes its sign at the latter stage of the emergence. The twist number of the whole active region remains on the order of 10 −1 turns during the emergence of the active region. Conclusions. We find that the magnetic flux tube with low twist also could emerge into the solar atmosphere.

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Section: Magnetic Propertiessupporting

confidence: 92%

Section: Summary and Discussionmentioning

confidence: 99%

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Naked emergence of an anti-Hale active region I. Overall evolution and magnetic properties

Wang,

Yan,

Kong

et al. 2021

Preprint

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“…First, to treat SOHO/MDI and SDO/HMI data by the same procedures to ensure the homogeneity of the derived magnetic flux values. Second, to ensure the consistency of the data reduction techniques applied in this work and in our previous works on AR emergence (Kutsenko, Abramenko, & Pevtsov 2019;Kutsenko, Abramenko, & Kutsenko 2021) in order to perform the comparison of the results. The SDO/HMI algorithm for the lineof-sight magnetic field calculations is similar to that for SOHO/MDI data.…”

Section: Datamentioning

confidence: 99%

“…Most of ARs in our sample containsunspots. For type I and type II ARs the data allow us to derive the flux emergence rate using the technique presented in Kutsenko, Abramenko, & Pevtsov (2019). The relationship between the peak magnetic flux, Φ , and flux emergence rate for these ARs is shown in Fig.…”

Section: The Flux Emergence Rate Of Flare-productive Arsmentioning

confidence: 99%

A statistical study of magnetic flux emergence in solar active regions prior to strongest flares

Kutsenko¹,

Abramenko²,

Plotnikov³

2021

Preprint

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Using the data on magnetic field maps and continuum intensity for Solar Cycles 23 and 24, we explored 100 active regions (ARs) that produced M5.0 or stronger flares. We focus on the presence/absence of the emergence of magnetic flux in these ARs 2-3 days before the strong flare onset. We found that 29 ARs in the sample emerged monotonously amidst quiet-Sun area. A major emergence of a new magnetic flux within pre-existing AR yielding the formation of a complex flare-productive configuration was observed in another 24 cases. For 30 ARs, an insignificant (in terms of the total magnetic flux of pre-existing AR) emergence of a new magnetic flux within the pre-existing magnetic configuration was observed; for some of them the emergence resulted in a formation of a configuration with a small -sunspot. 11 out of 100 ARs exhibited no signatures of magnetic flux emergence during the entire interval of observation. In 6 cases the emergence was in progress when the AR appeared on the Eastern limb, so that the classification and timing of emergence were not possible. We conclude that the recent flux emergence is not a necessary and/or sufficient condition for strong flaring of an AR. The flux emergence rate of analysed here flare-productive ARs was compared with that for flare-quiet ARs analysed in our previous studies. We revealed that the flare-productive ARs tend to display faster emergence than the flare-quiet ones.

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The Magnetic Power Spectra of Decaying Active Regions: New Evidence for the Large-Scale Magnetic Flux Bundle Submergence?

Kutsenko,

Abramenko,

Kutsenko

2024

Sol Phys

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Extended statistical analysis of emerging solar active regions

Cited by 19 publications

References 75 publications

Naked emergence of an anti-Hale active region I. Overall evolution and magnetic properties

Naked emergence of an anti-Hale active region I. Overall evolution and magnetic properties

A statistical study of magnetic flux emergence in solar active regions prior to strongest flares

The Magnetic Power Spectra of Decaying Active Regions: New Evidence for the Large-Scale Magnetic Flux Bundle Submergence?

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