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Extreme solar activity fluctuations and the occurrence of solar grand minima and maxima episodes, are well established, observed features of the solar cycle. Nevertheless, such extreme activity fluctuations and the dynamics of the solar…

Solar and Stellar Astrophysics · Physics 2018-03-30 D. Passos , D. Nandy , S. Hazra , I. Lopes

We propose that grand minima in solar activity are caused by simultaneous fluctuations in the meridional circulation and the Babcock-Leighton mechanism for the poloidal field generation in the flux transport dynamo model. We present the…

Solar and Stellar Astrophysics · Physics 2015-06-16 Bidya Binay Karak , Arnab Rai Choudhuri

We explore a reduced Babcock-Leighton (BL) dynamo model based on delay differential equations using numerical bifurcation analysis. This model reveals hysteresis, seen in the recent mean-field dynamo model and the direct numerical…

Solar and Stellar Astrophysics · Physics 2018-05-01 Bindesh Tripathi , Dibyendu Nandy , Soumitro Banerjee

Context. Solar activity cycles vary in amplitude and duration. The variations can be at least partly explained by fluctuations in dynamo parameters. Aims. We want to restrict uncertainty in fluctuating dynamo parameters and find out which…

Solar and Stellar Astrophysics · Physics 2018-07-18 L. L. Kitchatinov , A. V. Mordvinov , A. A. Nepomnyashchikh

Dynamo models relying on the Babcock-Leighton mechanism are successful in reproducing most of the solar magnetic field dynamical characteristics. However, considering that such models operate only above a lower magnetic field threshold,…

Solar and Stellar Astrophysics · Physics 2013-07-17 Sabrina Sanchez , Alexandre Fournier , Katia Pinheiro , Julien Aubert

Parameters of a special kind of \alpha-effect known in dynamo theory as the Babcock-Leighton mechanism are estimated using the data of sunspot catalogs. The estimates evidence the presence of the Babcock-Leighton \alpha-effect on the Sun.…

Solar and Stellar Astrophysics · Physics 2013-05-14 S. V. Olemskoy , A. R. Choudhuri , L. L. Kitchatinov

The Sun occasionally goes through Maunder-like extended grand minima when its magnetic activity drops considerably from the normal activity level for several decades. Many possible theories have been proposed to explain the origin of these…

Solar and Stellar Astrophysics · Physics 2018-06-21 Bidya Binay Karak , Mark Miesch

Long-term sunspot observations and solar activity reconstructions reveal that the Sun occasionally slips into quiescent phases known as solar grand minima, the dynamics during which is not well understood. We use a flux transport dynamo…

Solar and Stellar Astrophysics · Physics 2022-09-30 Chitradeep Saha , Sanghita Chandra , Dibyendu Nandy

The Sun and solar-type stars exhibit irregular cyclic variations in their magnetic activity over long time scales. To understand this irregularity, we employed the flux transport dynamo models to investigate the behavior of one solar mass…

Solar and Stellar Astrophysics · Physics 2024-12-25 Vindya Vashishth

One of the most striking manifestations of orderly behavior emerging out of complex interactions in any astrophysical system is the 11-year cycle of sunspots. However, direct sunspot observations and reconstructions of long-term solar…

Solar and Stellar Astrophysics · Physics 2025-04-24 Chitradeep Saha , Suprabha Mukhopadhyay , Dibyendu Nandy

We introduce on/off intermittency into a mean field dynamo model by imposing stochastic fluctuations in either the alpha effect or through the inclusion of a fluctuating electromotive force. Sufficiently strong small scale fluctuations with…

Astrophysics · Physics 2008-03-27 A. Brandenburg , E. A. Spiegel

The Sun is a magnetic star whose cyclic activity is thought to be linked to internal dynamo mechanisms. A combination of numerical modelling with various levels of complexity is an efficient and accurate tool to investigate such intricate…

Solar and Stellar Astrophysics · Physics 2015-05-19 L. Jouve , M. R. E. Proctor , G. Lesur

The occurrence of grand minima like the Maunder minimum is an intriguing aspect of the sunspot cycle. We use the flux transport dynamo model to explain the grand minima, showing that they arise when either the poloidal field or the…

Solar and Stellar Astrophysics · Physics 2013-07-23 Bidya Binay Karak , Arnab Rai Choudhuri

The hemispheric asymmetry of sunspot activity observed possesses a regular component varying on a time scale of several solar cycles whose origin and properties are currently debated. This paper addresses the question of whether the…

Solar and Stellar Astrophysics · Physics 2019-05-08 Alexander Nepomnyashchikh , Sudip Mandal , Dipankar Banerjee , Leonid Kitchatinov

The 11-yr cycle of sunspots undergo amplitude modulation over longer timescales. As a part of this long-term modulation in solar activity, the decennial rhythm occasionally breaks, with quiescent phases with very few sunspots observed over…

Solar and Stellar Astrophysics · Physics 2025-09-05 Chitradeep Saha , Sanghita Chandra , Dibyendu Nandy

The flux transport dynamo, in which the poloidal magnetic field is generated by the Babcock--Leighton mechanism and the meridional circulation plays a crucial role, has emerged as an attractive model for the solar cycle. Based on…

Solar and Stellar Astrophysics · Physics 2018-09-05 Arnab Rai Choudhuri

The large-scale magnetic field in the Sun varies with a period of approximately 22 years, although the amplitude of the cycle is subject to long-term modulation with recurrent phases of significantly reduced magnetic activity. It is…

Solar and Stellar Astrophysics · Physics 2015-06-19 Laura Cole , Paul Bushby

Like the solar cycle, stellar activity cycles are also irregular. Observations reveal that rapidly rotating (young) Sun-like stars exhibit a high level of activity with no Maunder-like grand minima and rarely display smooth regular activity…

Solar and Stellar Astrophysics · Physics 2023-05-10 Vindya Vashishth , Bidya Binay Karak , Leonid Kitchatinov

We propose that the poloidal field at the end of the last sunspot cycle before the Maunder minimum fell to a very low value due to fluctuations in the Babcock--Leighton process. With this assumption, a flux transport dynamo model is able to…

Solar and Stellar Astrophysics · Physics 2010-11-02 Arnab Rai Choudhuri , Bidya Binay Karak

A combination of diamagnetic pumping and a nonlocal alpha-effect of the Babcock-Leighton type in a solar dynamo model helps to reproduce observations of solar magnetic activity. The period of the solar cycle can be reproduced without…

Solar and Stellar Astrophysics · Physics 2015-05-30 L. L. Kitchatinov , S. V. Olemskoy
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