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Sunspots are obvious observable manifestations of the toroidal magnetic field generated through the dynamo in the convection zone. They appear in different sizes, having a wide distribution in their area. We analyse the sunspot group area…

Solar and Stellar Astrophysics · Physics 2026-02-10 Bidya Binay Karak , Soumya Mishra , Anu Sreedevi

We investigate relative role of various types of solar wind streams in generation of magnetic storms. On the basis of the OMNI data of interplanetary measurements for the period of 1976-2000 we analyze 798 geomagnetic storms with Dst < -50…

Space Physics · Physics 2012-05-18 Yu. I. Yermolaev , N. S. Nikolaeva , I. G. Lodkina , M. Yu. Yermolaev

Solar magnetic activity follows regular cycles of about 11 years with an inversion of polarity in the poles every 22 years. This changing surface magnetism impacts the properties of the acoustic modes. The acoustic mode frequency shifts are…

Solar and Stellar Astrophysics · Physics 2024-11-27 Rafael A. Garcia , Sylvain N. Breton , David Salabert , Sushant C. Tripathy , Kiran Jain , Savita Mathur , Eva Panetier

The peculiar behaviour of the solar cycle 23 and its prolonged minima has been one of the most studied problems over the last few years. In the present paper, we study the asymmetries in active region magnetic flux in the northern and…

Solar and Stellar Astrophysics · Physics 2015-02-03 Juie Shetye , Durgesh Tripathi , Mausumi Dikpati

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

As a large-scale motion on the Sun, the meridional flow plays an important role in determining magnetic structure and strength and solar cycle. However, the meridional flow near the solar poles is still unclear. The Hinode observations show…

Solar and Stellar Astrophysics · Physics 2024-07-29 Shuhong Yang , Jie Jiang , Zifan Wang , Yijun Hou , Chunlan Jin , Qiao Song , Yukun Luo , Ting Li , Jun Zhang , Yuzong Zhang , Guiping Zhou , Yuanyong Deng , Jingxiu Wang

Using time-distance helioseismic measurements of meridional flow in the near-surface shear layer over a period of 14 years, starting from May 2010, we probe the depth structure and evolution of its cross-equatorial part. We confirm that the…

Solar and Stellar Astrophysics · Physics 2025-12-16 Anisha Sen , S. P. Rajaguru , Ruizhu Chen , Junwei Zhao , Shukur Kholikov

Context. The Sun shows an activity cycle that is caused by its varying global magnetic field. During a solar cycle, sunspots, i.e. extended regions of strong magnetic fields, occur in activity belts that are slowly migrating from middle to…

Solar and Stellar Astrophysics · Physics 2015-11-25 D. Utz , R. Muller , S. Thonhofer , A. Veronig , A. Hanslmeier , M. Bodnárová , M. Bárta , J. C. del Toro Iniesta

We study the effects of the magnetic fields on the formation of massive, self-gravitationally bound cores (MBCs) in high-speed cloud-cloud collisions (CCCs). Extending our previous work (Sakre et al. 2021), we perform magnetohydrodynamic…

Astrophysics of Galaxies · Physics 2023-05-24 Nirmit Sakre , Asao Habe , Alex R. Pettitt , Takashi Okamoto , Rei Enokiya , Yasuo Fukui , Takashi Hosokawa

The dynamic activity of the Sun -- sustained by a magnetohydrodynamic dynamo mechanism working in its interior -- modulates the electromagnetic, particulate and radiative environment in space. While solar activity variations on short…

Solar and Stellar Astrophysics · Physics 2021-03-31 Dibyendu Nandy

OB stars exhibit various types of spectral variability associated with wind structures, including the apparently ubiquitous discrete absorption components (DACs). These are proposed to be caused by either magnetic fields or non-radial…

To what extent magnetic fields affect how molecular clouds (MCs) fragment and create dense structures is an open question. We present a numerical study of cloud fragmentation using the SILCC-Zoom simulations. These simulations follow the…

Astrophysics of Galaxies · Physics 2023-07-26 S. Ganguly , S. Walch , D. Seifried , S. D. Clarke , M. Weis

The solar magnetic field, thought to be generated by the motion of plasma within the Sun, alternates on the order of 11-year cycles and is incompletely understood. Industries rely on accurate forecasts of solar activity, but can solar…

Solar and Stellar Astrophysics · Physics 2025-02-20 Floe Foxon

Many stars across all classes possess strong enough magnetic fields to influence dynamical flow of material off the stellar surface. For the case of massive stars (O and B types), about 10\% of them harbour strong, globally ordered (mostly…

Solar and Stellar Astrophysics · Physics 2023-04-05 Asif ud-Doula , Stan Owocki

Planar magnetic structures (PMSs) are periods in the solar wind during which interplanetary magnetic field vectors are nearly parallel to a single plane. One of the specific regions where PMSs have been reported are coronal mass ejection…

Solar and Stellar Astrophysics · Physics 2017-01-31 Erika Palmerio , Emilia K. J. Kilpua , Neel P. Savani

Understanding the irregular variation of the solar cycle is crucial due to its significant impact on global climates and the heliosphere. Since the polar magnetic field determines the amplitude of the next solar cycle, variations in the…

Solar and Stellar Astrophysics · Physics 2024-12-25 Pawan Kumar

The magnetic cycle on the Sun consists of two consecutive 11-yr sunspot cycles and exhibits a polarity reversal around sunspot maximum. Although solar dynamo theories have progressively become more sophisticated, the details as to how the…

Solar and Stellar Astrophysics · Physics 2025-01-29 S. Bellotti , P. Petit , S. V. Jeffers , S. C. Marsden , J. Morin , A. A. Vidotto , C. P. Folsom , V. See , J. -D. do Nascimento

Decay and dispersal of the tilted Bipolar Magnetic Regions (BMRs) on the solar surface are observed to produce large-scale poloidal field, which acts as the seed for the toroidal field and, thus, the next sunspot cycle. However, various…

Solar and Stellar Astrophysics · Physics 2024-04-17 Pawan Kumar , Bidya Binay Karak , Anu Sreedevi

Based on data obtained from Wilcox Solar Observatiry the solar polar magnetic fields reversals in cycles 21\,--\,25 were considered. The results indicate that the polarity reversal occurs at the maximum of sunspot activity of each cycle,…

Solar and Stellar Astrophysics · Physics 2025-11-03 Irina A. Bilenko

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