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Mean field dynamo theory deals with various mean quantities and does not directly throw any light on the question of existence of flux tubes. We can, however, draw important conclusions about flux tubes in the interior of the Sun by…

Astrophysics · Physics 2008-11-26 Arnab Rai Choudhuri

By using the unique database of SOHO/MDI full disk magnetograms from 1996 September to 2011 January, covering the entire solar cycle 23, we analyze the time-variability of the solar magnetic flux spectrum and study the properties of…

Solar and Stellar Astrophysics · Physics 2015-06-18 C. l. Jin , J. X. Wang

There have been numerous reports of quasiperiodicities in solar activity in the intermediate period range. However, no accepted explanation for the episodic occurrence of quasiperiodicities has emerged. This paper examines the possibility…

Solar and Stellar Astrophysics · Physics 2015-10-12 Ian Edmonds

The meridional circulation at high latitudes is crucial to the build-up and reversal of the Sun's polar magnetic fields. Here we characterize the axisymmetric flows by applying a magnetic feature cross-correlation procedure to high…

Solar and Stellar Astrophysics · Physics 2013-03-26 Lisa Rightmire-Upton , David H. Hathaway , Katie Kosak

Following Couvidat (2013), we analyze data from the Helioseismic and Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA) instruments onboard the Solar Dynamics Observatory: Doppler velocity and continuum intensity at 6173 A as…

Solar and Stellar Astrophysics · Physics 2015-06-16 Sebastien Couvidat

We report on observation of the unusual kind of solar microflares, presumably associated with the so-called "topological trigger" of magnetic reconnection, which was theoretically suggested long time ago by Gorbachev et al. (Sov. Ast. 1988,…

Solar and Stellar Astrophysics · Physics 2017-11-15 Yurii V. Dumin , Boris V. Somov

Solar inter-network magnetic field is the weakest component of solar magnetism, but contributes most of the solar surface magnetic flux. The study on its origin has been constrained by the inadequate tempo-spatial resolution and sensitivity…

Solar and Stellar Astrophysics · Physics 2015-05-26 Chunlan Jin , Jingxiu Wang

Low-m inertial modes have been recently discovered in the Sun's high-latitude regions. In this study, we characterize the observational properties of the m = 1 mode by analyzing time-distance subsurface flow maps. Synoptic flow maps,…

Solar and Stellar Astrophysics · Physics 2025-06-25 Boyang Ding , Junwei Zhao , Ruizhu Chen , Matthias Waidele , Sushant S. Mahajan , Oana Vesa

The paper presents a study of kinematic axisymmetric mean-field dynamo models for a case of the meridional circulation with a deep-seated stagnation point and a strong return flow at the bottom of the convection zone. This kind of…

Solar and Stellar Astrophysics · Physics 2015-05-27 V. V. Pipin , A. G. Kosovichev

We use 2D numerical simulations and eikonal approximation, to study properties of MHD waves traveling below the solar surface through the magnetic structure of sunspots. We consider a series of magnetostatic models of sunspots of different…

Astrophysics · Physics 2011-02-11 E. Khomenko , A. Kosovichev , M. Collados , K. Parchevsky , V. Olshevsky

We present mid-IR N-band $(\lambda_{eff} = 10.2\micron)$ photometry of a carefully selected sample of T Tauri stars thought to be single from the Taurus-Auriga molecular cloud. Infrared excesses in these stars are generally attributed to…

We present a comparative seismic study of conditions around and beneath isolated sunspots. Using the European Grid of Solar Observations' Solar Feature Catalogue of sunspots derived from SOHO/MDI continuum and magnetogram data, 1996-2005,…

Astrophysics · Physics 2009-11-13 S. Zharkov , C. Nicholas , M. J. Thompson

Total solar irradiance (TSI) has been monitored from space since 1978. The measurements show a prominent variability in phase with the solar cycle, as well as fluctuations on timescales shorter than a few days. However, the measurements…

Solar and Stellar Astrophysics · Physics 2020-08-26 Theodosios Chatzistergos , Ilaria Ermolli , Fabrizio Giorgi , Natalie A. Krivova , Cosmin Constantin Puiu

Analysis of the structure and dynamics of the magnetic field of the Sun is fundamental for understanding of the origin of solar activity and variability as well as for the study of solar-terrestrial relations. Observations of the large…

Solar and Stellar Astrophysics · Physics 2018-02-21 E. A. Gavryuseva

The Sun is the primary source of energy for Earth and one of the main external drivers of its climate. Solar irradiance -- the radiative power emitted by the Sun and received at 1-AU -- varies on all observable timescales. It is measured as…

Solar and Stellar Astrophysics · Physics 2026-04-22 D. Temaj , N. A. Krivova , T. Chatzistergos , S. K. Solanki , B. Hofer

An approximate analytical solution for the rotating twisted magnetosphere of magnetars is presented. The poloidal flux is approximated by the self-similar twisted dipole field. The toroidal field is obtained by the minimum torque model.…

High Energy Astrophysical Phenomena · Physics 2025-12-05 H. Tong , L. Chen

We use images of high spatial and temporal resolution, obtained using both ground- and space-based instrumentation, to investigate the role magnetic field inclination angles play in the propagation characteristics of running penumbral waves…

Solar and Stellar Astrophysics · Physics 2015-06-17 D. B. Jess , V. E. Reznikova , T. Van Doorsselaere , P. H. Keys , D. H. Mackay

We present a reconstruction of the spectral solar irradiance since 1700 using the SATIRE-T2 (Spectral And Total Irradiance REconstructions for the Telescope era version 2) model. This model uses as input magnetograms simulated with a…

Solar and Stellar Astrophysics · Physics 2016-05-25 M. Dasi-Espuig , J. Jiang , N. A. Krivova , S. K. Solanki , Y. C. Unruh , K. L. Yeo

Total and spectral solar irradiance are key parameters in the assessment of solar influence on changes in the Earth's climate. We present a reconstruction of daily solar irradiance obtained using the SATIRE-S model spanning 1974 to 2013…

Solar and Stellar Astrophysics · Physics 2015-07-07 K. L. Yeo , N. A. Krivova , S. K. Solanki , K. H. Glassmeier

For quantum electronics, the possibility to finely tune the properties of magnetic topological insulators (TIs) is a key issue. We studied solid solutions between two isostructural Z$_2$ TIs, magnetic MnBi$_2$Te$_4$ and nonmagnetic…