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Linking solar wind properties to the activities and characteristics of its source regions can enhance our understanding of its origin and generation mechanisms. Using the Mount Wilson magnetic classification (MWMC), we categorize all active…

Solar and Stellar Astrophysics · Physics 2025-10-13 Xinzheng Shi , Hui Fu , Zhenghua Huang , Limei Yan , Qi Liu , Lidong Xia

Aims. Our aim is to examine the solar cycle variability of magnetically simple and complex active region. Methods. We studied simple ($\alpha$ and $\beta$) and complex ($\beta\gamma$ and $\beta\gamma\delta$) active regions based on the…

Solar and Stellar Astrophysics · Physics 2019-09-11 Shabnam Nikbakhsh , Eija Tanskanen , Maarit Käpylä , Thomas Hackman

A magnetic power spectral analysis is performed on 53 solar active regions, observed from August 2011 to July 2012. Magnetic field data obtained from the Helioseismic and Magnetic Imager, inverted as Active Region Patches, are used to study…

Solar and Stellar Astrophysics · Physics 2016-12-28 Revati S. Mandage , R. T. James McAteer

The emergence and magnetic evolution of solar active regions (ARs) of beta-gamma-delta type, which are known to be highly flare-productive, were studied with the SOHO/MDI data in Cycle 23. We selected 31 ARs that can be observed from their…

Solar and Stellar Astrophysics · Physics 2015-08-19 Kan Takizawa , Reizaburo Kitai

Data for 3046 solar active regions (ARs) observed since May 12, 1996 to December 27, 2021 were utilized to explore how the magnetic fluxes from ARs of different complexity follow the solar cycle. Magnetograms from the Michelson Doppler…

Solar and Stellar Astrophysics · Physics 2022-12-15 Valentina I. Abramenko , Regina A. Suleymanova , Anastasija V. Zhukova

Wavelet analysis of different solar activity indices, sunspot numbers, sunspot areas, flare index, magnetic fields, etc., allows us to investigate the time evolution of some specific features of the solar activity and the underlying dynamo…

Solar and Stellar Astrophysics · Physics 2013-05-10 Stefano Sello

Active regions (AR) appearing on the surface of the Sun are classified into $\alpha$, $\beta$, $\gamma$, and $\delta$ by the rules of the Mount Wilson Observatory, California on the basis of their topological complexity. Amongst these, the…

Solar and Stellar Astrophysics · Physics 2016-03-09 Piyali Chatterjee , Viggo Hansteen , Mats Carlsson

An analysis of the tilt angles of the active regions in 15-24 activity cycles was performed. We used data from measurements of magnetic fields in the sunspot umbra in the period 1918 -2019 at the Mount Wilson Observatory, as well as the…

Solar and Stellar Astrophysics · Physics 2025-09-24 Andrey Tlatov

The solar magnetic field is responsible for all aspects of solar activity. Sunspots are the main manifestation of the ensuing solar activity. Combining high-resolution and synoptic observations has the ambition to provide a comprehensive…

Using magnetic field maps acquired by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory we measured rotation rates of 864 active and 322 ephemeral regions observed between 2010 and 2016. We found smaller magnetic…

Solar and Stellar Astrophysics · Physics 2020-11-25 Alexander S. Kutsenko

In this dataset we provide a comprehensive collection of magnetograms (images quantifying the strength of the magnetic field) from the National Aeronautics and Space Administration's (NASA's) Solar Dynamics Observatory (SDO). The dataset…

Solar and Stellar Astrophysics · Physics 2024-02-13 Laura E. Boucheron , Ty Vincent , Jeremy A. Grajeda , Ellery Wuest

Context: The evolution of solar active regions is still not fully understood. The growth and decay of active regions have mostly been studied in case-by-case studies. Aims: Instead of studying the evolution of active regions case by case,…

Solar and Stellar Astrophysics · Physics 2021-03-24 Michal Švanda , M. Sobotka , L. Mravcová , T. Výbošťoková

Here, we analyzed magnetic elements of the solar active regions (ARs) observed in the line-of-sight magnetograms (the 6173 \AA~Fe \small{I} line) recorded with the Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager (HMI). The…

Solar and Stellar Astrophysics · Physics 2021-09-28 M. A. Moradhaseli , M. Javaherian , N. Fathalian , H. Safari

We study the evolution of the observed photospheric magnetic field and the modeled global coronal magnetic field during the past 3 1/2 solar activity cycles observed since the mid-1970s. We use synoptic magnetograms and extrapolated…

Solar and Stellar Astrophysics · Physics 2015-06-15 G. J. D. Petrie

A statistical study of 77 solar active regions (ARs) is conducted to investigate the existence of identifiable correlations between the subsurface structural disturbances and the activity level of the active regions. The disturbances…

Solar and Stellar Astrophysics · Physics 2015-12-23 Chia-Hsien Lin

The origin of the quiet Sun magnetism is under debate. Investigating the solar cycle variation observationally in more detail can give us clues about how to resolve the controversies. We investigate the solar cycle variation of the most…

Solar and Stellar Astrophysics · Physics 2022-09-21 Maarit J. Korpi-Lagg , Andreas Korpi-Lagg , Nigul Olspert , Hong-Linh Truong

Identifying solar active regions (ARs), which consist of one or more pairs of magnetic patches with opposite polarities, is essential due to their significant role in dynamic solar atmospheric phenomena. In this study, we analyze ARs during…

Solar and Stellar Astrophysics · Physics 2025-09-16 Zahra Tajik , Hasan Rezaei , Mehdi Simiari , Hossien Safari

The evolution of the photospheric magnetic field during the declining phase and minimum of Cycle 23 and the recent rise of Cycle 24 are compared with the behavior during previous cycles. We used longitudinal full-disk magnetograms from the…

Solar and Stellar Astrophysics · Physics 2012-08-28 Gordon Petrie

Two different multi-resolution analyses are used to decompose the structure of active region magnetic flux into concentrations of different size scales. Lines separating these opposite polarity regions of flux at each size scale are found.…

Astrophysics · Physics 2009-11-13 J. Ireland , C. A. Young , R. T. J. McAteer , C. Whelan , R. J. Hewett , P. T. Gallagher

We study the evolution of electric currents during the emergence of magnetic flux in the solar photosphere and the differences exhibited between solar active regions of different Hale complexity classes. A sample of 59 active regions was…

Solar and Stellar Astrophysics · Physics 2024-08-06 I. Kontogiannis , M. K. Georgoulis
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