Long-term evolution of magnetic fields in flaring Active Region NOAA 12673

Abstract During the lifetime of AR 12673, its magnetic field evolved drastically and produced numerous large flares. In this study, using full maps of the Sun observed by the Solar Dynamics Observatory and the Solar Terrestrial Relations Observatory, we identified that AR 12673 emerged in decayed AR 12665, which had survived for two solar rotations. Although both ARs emerged at the same location, they possessed different characteristics and different flare productivities. Therefore, it is important to study the long-term magnetic evolution of both ARs to identify the distinguishing characteristics of an AR that can produce large solar flares. We used the Space-weather Helioseismic and Magnetic Imager Active Region Patch data to investigate the evolution of the photospheric magnetic field and other physical properties of the recurring ARs during five Carrington rotations. All these investigated parameters dynamically evolved through a series of solar rotations. We compared the long-term evolution of AR 12665 and AR 12673 to understand the differences in their flare-producing properties. We also studied the relation of the long-term evolution of these ARs with the presence of active longitude. We found that the magnetic flux and complexity of AR 12673 developed much faster than those of AR 12665. Our results confirmed that a strong emerging flux that emerged in the pre-existing AR near the active longitude created a very strong and complex AR that produced large flares.

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Long-term evolution of the heliospheric magnetic field inferred from cosmogenic 44Ti activity in meteorites

Astronomy and Astrophysics ◽

10.1051/0004-6361/201730392 ◽

2018 ◽

Vol 610 ◽

pp. A28 ◽

Cited By ~ 2

Author(s):

S. Mancuso ◽

C. Taricco ◽

P. Colombetti ◽

S. Rubinetti ◽

N. Sinha ◽

...

Keyword(s):

Magnetic Field ◽

Ice Cores ◽

Long Term Evolution ◽

Galactic Cosmic Rays ◽

Sunspot Activity ◽

Cosmogenic Isotopes ◽

Heliospheric Magnetic Field ◽

The Past ◽

Term Evolution

Typical reconstructions of historic heliospheric magnetic field (HMF) BHMF are based on the analysis of the sunspot activity, geomagnetic data or on measurement of cosmogenic isotopes stored in terrestrial reservoirs like trees (14C) and ice cores (10Be). The various reconstructions of BHMF are however discordant both in strength and trend. Cosmogenic isotopes, which are produced by galactic cosmic rays impacting on meteoroids and whose production rate is modulated by the varying HMF convected outward by the solar wind, may offer an alternative tool for the investigation of the HMF in the past centuries. In this work, we aim to evaluate the long-term evolution of BHMF over a period covering the past twenty-two solar cycles by using measurements of the cosmogenic 44Ti activity (τ1∕2 = 59.2 ± 0.6 yr) measured in 20 meteorites which fell between 1766 and 2001. Within the given uncertainties, our result is compatible with a HMF increase from 4.87-0.30+0.24 nT in 1766 to 6.83-0.11+0.13 nT in 2001, thus implying an overall average increment of 1.96-0.35+0.43 nT over 235 years since 1766 reflecting the modern Grand maximum. The BHMF trend thus obtained is then compared with the most recent reconstructions of the near-Earth HMF strength based on geomagnetic, sunspot number, and cosmogenic isotope data.

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Long-term Evolution of the Sun’s Magnetic Field during Cycles 15–19 Based on Their Proxies from Kodaikanal Solar Observatory

The Astrophysical Journal ◽

10.3847/2041-8213/abba80 ◽

2020 ◽

Vol 902 (1) ◽

pp. L15

Author(s):

Alexander V. Mordvinov ◽

Bidya Binay Karak ◽

Dipankar Banerjee ◽

Subhamoy Chatterjee ◽

Elena M. Golubeva ◽

...

Keyword(s):

Magnetic Field ◽

Long Term Evolution ◽

Solar Observatory ◽

Term Evolution

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On the Dynamics of the Largest Active Region of the Solar Cycle 24

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317008924 ◽

2017 ◽

Vol 13 (S335) ◽

pp. 32-35

Author(s):

Ranadeep Sarkar ◽

Nandita Srivastava ◽

Sajal Kumar Dhara

Keyword(s):

Magnetic Field ◽

Solar Cycle ◽

Active Region ◽

Comparative Study ◽

Lorentz Force ◽

Sunspot Group ◽

Solar Dynamics Observatory ◽

Solar Cycle 24 ◽

Solar Dynamics ◽

Cycle 24

AbstractWe have studied the dynamics of the solar active region (AR) NOAA 12192 using full-disc continuum images and the vector magnetograms observed by the Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO). AR 12192 is the largest region of the solar cycle 24. It underwent a noticeable growth and produced 6 X-class, 22 M-class and 53 C-class flares during its disc passage. But the most peculiar fact of this AR is that it was associated with only one CME in spite of producing several X-class flares. In this work, we present the area evolution of this giant sunspot group during the first three rotations when it appeared as AR 12172, AR 12192 and AR 12209, respectively. We have also attempted to make a comparative study of the flare-related photospheric magnetic field and Lorentz force changes for both the eruptive and non-eruptive flares produced by AR 12192.

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Reconstructing solar magnetic fields from historical observations

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935606 ◽

2019 ◽

Vol 627 ◽

pp. A11

Author(s):

I. O. I. Virtanen ◽

I. I. Virtanen ◽

A. A. Pevtsov ◽

L. Bertello ◽

A. Yeates ◽

...

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Large Scale ◽

Active Regions ◽

Long Term Evolution ◽

Photospheric Magnetic Field ◽

Solar Magnetic Fields ◽

Term Evolution ◽

Large Scale Field

Aims. The evolution of the photospheric magnetic field has only been regularly observed since the 1970s. The absence of earlier observations severely limits our ability to understand the long-term evolution of solar magnetic fields, especially the polar fields that are important drivers of space weather. Here, we test the possibility to reconstruct the large-scale solar magnetic fields from Ca II K line observations and sunspot magnetic field observations, and to create synoptic maps of the photospheric magnetic field for times before modern-time magnetographic observations. Methods. We reconstructed active regions from Ca II K line synoptic maps and assigned them magnetic polarities using sunspot magnetic field observations. We used the reconstructed active regions as input in a surface flux transport simulation to produce synoptic maps of the photospheric magnetic field. We compared the simulated field with the observed field in 1975−1985 in order to test and validate our method. Results. The reconstruction very accurately reproduces the long-term evolution of the large-scale field, including the poleward flux surges and the strength of polar fields. The reconstruction has slightly less emerging flux because a few weak active regions are missing, but it includes the large active regions that are the most important for the large-scale evolution of the field. Although our reconstruction method is very robust, individual reconstructed active regions may be slightly inaccurate in terms of area, total flux, or polarity, which leads to some uncertainty in the simulation. However, due to the randomness of these inaccuracies and the lack of long-term memory in the simulation, these problems do not significantly affect the long-term evolution of the large-scale field.

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An X-Ray Observations of a Gradual Coronal Mass Ejections (CMEs) on 15th April 2012

International Letters of Chemistry Physics and Astronomy ◽

10.18052/www.scipress.com/ilcpa.27.13 ◽

2014 ◽

Vol 27 ◽

pp. 13-19

Author(s):

Zety Sharizat Hamidi ◽

N.N.M. Shariff ◽

C. Monstein ◽

W.N.A. Wan Zulkifli ◽

M.B. Ibrahim ◽

...

Keyword(s):

Active Region ◽

Coronal Mass Ejections ◽

Solar Flares ◽

Solar Observation ◽

Solar Dynamics Observatory ◽

Gradual Process ◽

Solar Filament ◽

Solar Dynamics ◽

Important Character ◽

The Magnetic Field

In the present work, we will highlight the solar observation during 15th April 2012, solar filament eruption which is accompanied by an intense and gradual Coronal Mass Ejections (CMEs). The explosion of CMEs was observed at 2:12:06 UT and also can be observed by the Solar Dynamics Observatory (SDO) with an Active Region AR1458 is crackling with C-class solar flares. The solar flare class B3 and C2 were observed beginning 2241 UT and 0142 UT. The event is considered as second largest CMEs been detected since five years. Although the solar activity within a few days is considered quite low and there are no proton events were observed at geosynchronous orbit., the is still an unexpected explosion of CMEs can be occurred. The radio flux number (10.7 cm) exceeds 102 with the number of sunspot and area of sunspot increased to 77 and 270. The velocity of CMEs was calculated based on the LASCO2 data. From the results, it is clearly seen that the range of the velocity is between 200 kms-1 to 2000 kms-1. This wide of range proved that the mechanism of the CMEs is a gradual process. The explosion of CMEs velocity is located from 80º - 255º from North of the Sun. We can then conclude that currently, the rearrangement of the magnetic field, and solar flares may result in the formation of a shock that accelerates particles ahead of the CMEs loop and an active region play an important character in this event.

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Long time convergence of magnetohydrodynamic flows to alfvénic states

Journal of Plasma Physics ◽

10.1017/s0022377807006459 ◽

2007 ◽

Vol 73 (6) ◽

pp. 947-955

Author(s):

MANUEL NÚÑEZ

Keyword(s):

Magnetic Field ◽

Long Term Evolution ◽

Static Equilibrium ◽

Transient Processes ◽

Term Evolution ◽

Magnetohydrodynamic Flows ◽

Long Time ◽

Simple Class ◽

Turbulent Plasmas

AbstractAlfvénic states of a plasma, where velocity and magnetic field coincide, form a particular simple class of ideal equilibria and are also found in certain astrophysical phenomena. While transient processes of alignment in turbulent plasmas are well known and due to preferential spectral transfer, the possible long-term evolution of a magnetohydrodynamic plasma towards an alfvénic state has been rarely studied. It is shown that this tendency does not exist: neither specific ideal alfvénic equilibria nor the whole set of such states attract trajectories in any functional sense. Another possibility is that the perturbations of a static equilibrium could tend to become alfvénic, such as the classical Alfvén waves. We find that if these equilibria are current free, when a perturbation approaches an alfvénic state it immediately bounces away from it.

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