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Oscillation amplitudes are generally smaller within magnetically active regions like sunspots and plage, when compared to their surroundings. Such magnetic features, when viewed in spatially-resolved powermaps, appear as regions of…

Solar and Stellar Astrophysics · Physics 2016-05-30 S. Krishna Prasad , D. B. Jess , R. Jain , P. H. Keys

[Abridged] Bipolar magnetic regions are formed when loops of magnetic flux emerge at the solar photosphere. Our aim is to investigate the flux emergence process in a simulation of granular convection. In particular we aim to determine the…

Solar and Stellar Astrophysics · Physics 2012-08-09 Paul J Bushby , Vasilis Archontis

The buoyant transport of magnetic fields from the solar interior towards the surface plays an important role in the emergence of active regions, the formation of sunspots and the overall solar dynamo. Observations suggest that toroidal flux…

Solar and Stellar Astrophysics · Physics 2018-06-27 Bhishek Manek , Nicholas Brummell , Dongwook Lee

We study discrete surface solitons in semi-infinite, one-dimensional, nonlinear (Kerr), quasiperiodic waveguide arrays of the Fibonacci and Aubry-Andr\'e types, and explore different families of localized surface modes, as a function of…

Pattern Formation and Solitons · Physics 2015-06-03 Alejandro J. Martinez , Mario I. Molina

Observations of star-forming regions by the current and upcoming generation of submillimeter polarimeters will shed new light on the evolution of magnetic fields over the cloud-to-core size scales involved in the early stages of the star…

Astrophysics of Galaxies · Physics 2019-04-11 Kate Pattle , Laura Fissel

The ability to control the magnetic state provides a powerful means to tune the underlying band topology, enabling transitions between distinct electronic phases and the emergence of novel quantum phenomena. In this work, we address the…

We investigate the orientation of the photospheric magnetic fields in the solar polar region using observations from the Helioseismic and Magnetic Imager (HMI). Inside small patches of significant polarization, the inferred magnetic field…

Solar and Stellar Astrophysics · Physics 2021-06-04 Xudong Sun , Yang Liu , Ivan Milić , Ana Belén Griñón Marín

L1521F is found to be forming multiple cores and it is cited as an example of the densest core with an embedded VeLLO in a highly dynamical environment. We present the core-scale magnetic fields (B-fields) in the near vicinity of the VeLLO…

Using helioseismic holography strong evidence is presented that the phase (or equivalent travel-time) of helioseismic signatures in Dopplergrams within sunspots depend upon the line-of-sight angle in the plane containing the magnetic field…

Solar and Stellar Astrophysics · Physics 2010-02-12 H. Schunker , D. C. Braun , P. S. Cally

Inspired by observations of sunspots embedded in active regions, it is often assumed that large-scale, strong magnetic flux emerges from the Sun's deep interior in the form of arched, cylindrical structures, colloquially known as flux…

Solar and Stellar Astrophysics · Physics 2022-04-28 Bhishek Manek , Christina Pontin , Nicholas Brummell

We investigate the evolution of subsurface flows during the emergence and the active phase of sunspot regions using the time-distance helioseismology analysis of the full-disk Dopplergrams from the Helioseismic and Magnetic Imager (HMI)…

Solar and Stellar Astrophysics · Physics 2024-12-25 Alexander G. Kosovichev , Viacheslav M. Sadykov

Magnetostatic normal modes are investigated here in elongated rods. The dipolar field resulting from the dipole-dipole interactions is calculated numerically in points of the axis connecting opposite rod face centers (\emph{central axis})…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 H. Puszkarski , M. Krawczyk , J. -C. S. Levy

With the assumption that the optical variability timescale is dominated by the cooling time of the synchrotron process for BL Lac objects, we estimate time dependent magnetic field strength of the emission region for two BL Lac objects. The…

High Energy Astrophysical Phenomena · Physics 2022-01-19 Xu-Liang Fan , Da-Hai Yan , Qing-Wen Wu , Xu Chen

Investigation of propagation, conversion, and scattering of MHD waves in the Sun is very important for understanding the mechanisms of observed oscillations and waves in sunspots and active regions. We have developed 3D linear MHD numerical…

Astrophysics · Physics 2011-02-11 K. V. Parchevsky , A. G. Kosovichev

We perform two-dimensional relativistic magnetohydrodynamic simulations of a mildly relativistic shock propagating through an inhomogeneous medium. We show that the postshock region becomes turbulent owing to preshock density inhomogeneity,…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Yosuke Mizuno , Martin Pohl , Jacek Niemiec , Bing Zhang , Ken-Ichi Nishikawa , Philip E. Hardee

High degree solar mode frequencies as measured by ring diagrams are known to change in the presence of the strong magnetic fields found in active regions. We examine these changes in frequency for a large sample of active regions analyzed…

Solar and Stellar Astrophysics · Physics 2015-05-27 Charles S. Baldner , Richard S. Bogart , Sarbani Basu

A weak fluctuating magnetic field embedded into a turbulent conducting medium grows exponentially while its characteristic scale decays. In the ISM and protogalactic plasmas, the magnetic Pr is very large, so a broad spectrum of growing…

Astrophysics · Physics 2008-11-26 Alexander Schekochihin , Steven Cowley , Jason Maron , Leonid Malyshkin

The continuous high spatial-resolution Doppler observation of the Sun by Solar Dynamics Observatory / Helioseismic and Magnetic Imager allows us to compute helioseismic k-omega power-spectrum diagram using only oscillations inside a…

Solar and Stellar Astrophysics · Physics 2015-06-11 Junwei Zhao , Dean-Yi Chou

The theory of large scale dynamos is reviewed with particular emphasis on the magnetic helicity constraint in the presence of closed and open boundaries. In the presence of closed or periodic boundaries, helical dynamos respond to the…

Astrophysics · Physics 2009-11-07 A. Brandenburg , W. Dobler , K. Subramanian

The behavior of the low-frequency electromagnon in multiferroic DyMnO3 has been investigated in external magnetic fields and in a magnetically ordered state. Significant softening of the electromagnon frequency is observed for external…

Strongly Correlated Electrons · Physics 2011-03-03 A. M. Shuvaev , J. Hemberger , D. Niermann , F. Schrettle , A. Loidl , V. Yu. Ivanov , V. D. Travkin , A. A. Mukhin , A. Pimenov