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Observations of young open clusters have revealed a bimodal distribution of fast and slower rotation rates that has proven difficult to explain with predictive models of spin down that depend on rotation rates alone. The Metastable Dynamo…

Solar and Stellar Astrophysics · Physics 2015-06-08 Cecilia Garraffo , Jeremy J. Drake , Ofer Cohen

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

A variety of observations suggest that magnetic fields are present in all galaxies and galaxy clusters. These fields are characterized by a modest strength (10^{-7}-10^{-5} G) and huge spatial scale (~Mpc). It is generally assumed that…

Astrophysics · Physics 2008-11-26 Lawrence M. Widrow

We investigate the effect of the magnetic fields of M dwarf (dM) stars on potentially habitable Earth-like planets. These fields can reduce the size of planetary magnetospheres to such an extent that a significant fraction of the planet's…

Earth and Planetary Astrophysics · Physics 2013-07-01 A. A. Vidotto , M. Jardine , J. Morin , J. -F. Donati , P. Lang , A. J. B. Russell

We present the results of simulations of forced turbulence in a slab where the mean kinetic helicity has a maximum near the mid-plane, generating gradients of magnetic helicity of both large and small-scale fields. We also study systems…

Solar and Stellar Astrophysics · Physics 2010-11-30 A. Hubbard , A. Brandenburg

Observations of dwarf galaxies suggest the presence of large-scale magnetic fields. However the size and slow rotation of these galaxies appear insufficient to support a mean-field dynamo action to excite such fields. Here we suggest a new…

Astrophysics of Galaxies · Physics 2017-02-08 David Moss , Dmitri Sokoloff

Large-scale magnetic fields in galaxies are thought to be generated by a turbulent dynamo. However the same turbulence also leads to a small-scale dynamo which generates magnetic noise at a more rapid rate. The efficiency of the large-scale…

Astrophysics · Physics 2020-11-25 K. Subramanian

Stellar winds are an integral part of the underlying dynamo, the motor of stellar activity. The wind controls the star's angular momentum loss, which depends on the magnetic field geometry which varies significantly in time and latitude.…

Solar and Stellar Astrophysics · Physics 2021-03-16 P. Jakab , A. Brandenburg

Recent FERMI observations provide a lower limit of 10^{-15} G for the magnetic field strength in the intergalactic medium (IGM). This is consistent with theoretical expectations based on the Biermann battery effect, which predicts such IGM…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-18 Dominik R. G. Schleicher , Sharanya Sur , Robi Banerjee , Ralf S. Klessen , Christoph Federrath , Tigran Arshakian , Rainer Beck , Marco Spaans

The origin of magnetic fields in isolated and binary white dwarfs has been investigated in a series of recent papers. One proposal is that magnetic fields are generated through an alpha-omega dynamo during common envelope evolution. Here we…

Solar and Stellar Astrophysics · Physics 2018-10-16 Gordon Briggs , Lilia Ferrario , Christopher Tout , Dayal Wickramasinghe

Galaxies are observed to host magnetic fields with a typical total strength of around 15microgauss. A coherent large-scale field constitutes up to a few microgauss of the total, while the rest is built from strong magnetic fluctuations over…

Astrophysics of Galaxies · Physics 2024-01-09 Maarit J. Korpi-Lagg , Mordecai-Mark Mac Low , Frederick A. Gent

The effects of a magnetic field on a modulated phase is studied. A modulated phase is found to have two critical fields $H_{1}$ and $H_{2}$. For a large enough magnetic field. $H_1$ can be approximated by a linear law. As a result, the…

Condensed Matter · Physics 2015-06-25 Bambi Hu , Jian Zhou

The absence of planets interior to Mercury continues to puzzle terrestrial planet formation models, particularly when contrasted with the relatively high derived occurrence rates of short-period planets around Sun-like stars. Recent work…

Earth and Planetary Astrophysics · Physics 2021-05-05 Matthew S. Clement , John E. Chambers , Alan P. Jackson

In the quiet Sun, magnetic fields are usually observed as small-scale magnetic elements, `salt and pepper', covering the entire solar surface. By using 3D radiative MHD numerical simulations we demonstrate that these fields are a result of…

Solar and Stellar Astrophysics · Physics 2013-12-05 I. N. Kitiashvili , A. G. Kosovichev , N. N. Mansour , A. A. Wray

Mean-field galactic dynamo theory is the leading theory to explain the prevalence of regular magnetic fields in spiral galaxies, but its systematic comparison with observations is still incomplete and fragmentary. Here we compare…

Astrophysics of Galaxies · Physics 2016-12-14 Luke Chamandy , Anvar Shukurov , A. Russ Taylor

In this Letter, we provide constraints on the direction and magnitude of the pristine (i.e., unperturbed by the interaction with the Sun) local interstellar magnetic field. The constraints are based on analysis of the interstellar magnetic…

Space Physics · Physics 2020-01-29 Vladislav V. Izmodenov , Dmitry B. Alexashov

For a simple spherically symmetric mean-field dynamo model we investigate the possibility of determining the radial dependence of the coefficient $\alpha$. Growth rates for different magnetic field modes are assumed to be known by…

Astrophysics · Physics 2009-05-20 Frank Stefani , Gunter Gerbeth

Observations have suggested that some low-mass stars have larger radii than predicted by 1-D structure models. Some theoretical models have invoked very strong interior magnetic fields (of order 1 MG or more) as a possible cause of such…

Solar and Stellar Astrophysics · Physics 2016-03-09 Matthew K. Browning , Maria A. Weber , Gilles Chabrier , Angela P. Massey

Low-mass galaxies radio observations show in many cases surprisingly high levels of magnetic field. The mass and kinematics of such objects do not favour the development of effective large-scale dynamo action. We attempted to check if the…

Astrophysics of Galaxies · Physics 2018-03-14 Hubert Siejkowski , Marian Soida , Krzysztof T. Chyzy

Magnetic fields correlated on kiloparsec scales are seen in spiral galaxies. Their origin could be due to amplification of a small seed field by a turbulent galactic dynamo. We review the current status of the galactic dynamo, especially…

Astrophysics · Physics 2007-05-23 Kandaswamy Subramanian