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Papers by David Moss

Research paper thumbnail of TURBULENT DYNAMOS IN SPHERICAL SHELL SEGMENTS OF VARYING GEOMETRICAL EXTENT

The Astrophysical Journal, 2009

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Research paper thumbnail of Magnetic elds in barred galaxies II. Dynamo models

We study the generation and maintenance of large-scale magnetic elds in barred galaxies. We take ... more We study the generation and maintenance of large-scale magnetic elds in barred galaxies. We take a velocity eld (with strong noncircular components) from a published gas dynamical simulation of Athanassoula (1992), and use this as input to a galactic dynamo calculation. Our work is largely motivated by recent high quality VLA radio observations of the barred galaxy NGC 1097, and we compare our results in detail with the regular magnetic elds deduced from these observations. We are able to reproduce most of the conspicuous large-scale features of the observed regular eld, including the eld structure in the central regions, by using a simple mean- eld dynamo model in which the intensity of interstellar turbulence (more precisely, the turbulent diusivity) is enhanced by a factor of 2{6 in the dust lanes and near the circumnuclear ring. We argue that magnetic elds can be dynamically important, and therefore should be included in models of gas flow in barred galaxies.

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Research paper thumbnail of Vortex tube models for turbulent dynamo action

Physics of Plasmas, 1999

The possibility of dynamo action resulting from a pair of elongated vortex structures immersed in... more The possibility of dynamo action resulting from a pair of elongated vortex structures immersed in an electrically conducting fluid is investigated. For elongated vortex structures, the critical magnetic Reynolds number for dynamo action is about half that for the spherical rotors that have been studied previously. When applied to Kolmogorov turbulence with vortex structures of scale comparable to the dissipation

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Research paper thumbnail of Anharmonic and standing dynamo waves: theory and observation of stellar magnetic activity

Monthly Notices of the Royal Astronomical Society, 2006

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Research paper thumbnail of Intermittent Behaviour in Axisymmetric Mean-Field Dynamo Models in Spherical Shells

Monthly Notices of the Royal Astronomical Society, 1998

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Research paper thumbnail of Stellar Dynamo Waves: Asymptotic Configurations

Geophysical & Astrophysical Fluid Dynamics, 2004

... J. , 543: 1027–1043. [CrossRef], [Web of Science ®] View all references), to illustrate the s... more ... J. , 543: 1027–1043. [CrossRef], [Web of Science ®] View all references), to illustrate the scale of the relevant literature. A more systematic presentation of this literature can be found eg in a recent review by Ossendrijver (200321. Ossendrijver, M. 2003. “The stellar dynamo”. ...

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Research paper thumbnail of Local models of small-scale dynamo action

Le Journal de Physique IV, 1998

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Research paper thumbnail of Galactic dynamos with captured magnetic flux and an accretion flow

Astronomy and Astrophysics, 2001

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Research paper thumbnail of The relation between magnetic and material arms in models for spiral galaxies

Astronomy & Astrophysics, 2013

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Research paper thumbnail of Alleviating α quenching by solar wind and meridional flows

Astronomy & Astrophysics, 2011

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Research paper thumbnail of A solar mean field dynamo benchmark

Astronomy and Astrophysics, 2008

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Research paper thumbnail of The stability of nonlinear dynamos and the limited role of kinematic growth rates

The growth rate behavior of several kinematic dynamo models was investigated in the context of th... more The growth rate behavior of several kinematic dynamo models was investigated in the context of the observation that, as a rule, a magnetic field of a single symmetry dominates in the sun and other cosmic objects. For all dynamo models considered, it is shown that, as the dynamo numbers increase, the kinematic growth rates of fields of different parities are

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Research paper thumbnail of GALACTIC MAGNETISM: Recent Developments and Perspectives

Annual Review of Astronomy and Astrophysics, 1996

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Research paper thumbnail of Multiscale magnetic fields in spiral galaxies: evolution and reversals

Magnetic fields in nearby, star-forming galaxies reveal both large-scale patterns and small-scale... more Magnetic fields in nearby, star-forming galaxies reveal both large-scale patterns and small-scale structures. A large-scale field reversal may exist in the Milky Way but no such reversals have been observed so far in external galaxies. The effects of star-forming regions of galaxies need to be included when modelling the evolution of their magnetic fields, which can then be compared to

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Research paper thumbnail of TURBULENT DYNAMOS IN SPHERICAL SHELL SEGMENTS OF VARYING GEOMETRICAL EXTENT

The Astrophysical Journal, 2009

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Research paper thumbnail of Magnetic elds in barred galaxies II. Dynamo models

We study the generation and maintenance of large-scale magnetic elds in barred galaxies. We take ... more We study the generation and maintenance of large-scale magnetic elds in barred galaxies. We take a velocity eld (with strong noncircular components) from a published gas dynamical simulation of Athanassoula (1992), and use this as input to a galactic dynamo calculation. Our work is largely motivated by recent high quality VLA radio observations of the barred galaxy NGC 1097, and we compare our results in detail with the regular magnetic elds deduced from these observations. We are able to reproduce most of the conspicuous large-scale features of the observed regular eld, including the eld structure in the central regions, by using a simple mean- eld dynamo model in which the intensity of interstellar turbulence (more precisely, the turbulent diusivity) is enhanced by a factor of 2{6 in the dust lanes and near the circumnuclear ring. We argue that magnetic elds can be dynamically important, and therefore should be included in models of gas flow in barred galaxies.

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Research paper thumbnail of Vortex tube models for turbulent dynamo action

Physics of Plasmas, 1999

The possibility of dynamo action resulting from a pair of elongated vortex structures immersed in... more The possibility of dynamo action resulting from a pair of elongated vortex structures immersed in an electrically conducting fluid is investigated. For elongated vortex structures, the critical magnetic Reynolds number for dynamo action is about half that for the spherical rotors that have been studied previously. When applied to Kolmogorov turbulence with vortex structures of scale comparable to the dissipation

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Research paper thumbnail of Anharmonic and standing dynamo waves: theory and observation of stellar magnetic activity

Monthly Notices of the Royal Astronomical Society, 2006

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Research paper thumbnail of Intermittent Behaviour in Axisymmetric Mean-Field Dynamo Models in Spherical Shells

Monthly Notices of the Royal Astronomical Society, 1998

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Research paper thumbnail of Stellar Dynamo Waves: Asymptotic Configurations

Geophysical & Astrophysical Fluid Dynamics, 2004

... J. , 543: 1027–1043. [CrossRef], [Web of Science ®] View all references), to illustrate the s... more ... J. , 543: 1027–1043. [CrossRef], [Web of Science ®] View all references), to illustrate the scale of the relevant literature. A more systematic presentation of this literature can be found eg in a recent review by Ossendrijver (200321. Ossendrijver, M. 2003. “The stellar dynamo”. ...

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Research paper thumbnail of Local models of small-scale dynamo action

Le Journal de Physique IV, 1998

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Research paper thumbnail of Galactic dynamos with captured magnetic flux and an accretion flow

Astronomy and Astrophysics, 2001

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Research paper thumbnail of The relation between magnetic and material arms in models for spiral galaxies

Astronomy & Astrophysics, 2013

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Research paper thumbnail of Alleviating α quenching by solar wind and meridional flows

Astronomy & Astrophysics, 2011

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Research paper thumbnail of A solar mean field dynamo benchmark

Astronomy and Astrophysics, 2008

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Research paper thumbnail of The stability of nonlinear dynamos and the limited role of kinematic growth rates

The growth rate behavior of several kinematic dynamo models was investigated in the context of th... more The growth rate behavior of several kinematic dynamo models was investigated in the context of the observation that, as a rule, a magnetic field of a single symmetry dominates in the sun and other cosmic objects. For all dynamo models considered, it is shown that, as the dynamo numbers increase, the kinematic growth rates of fields of different parities are

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Research paper thumbnail of GALACTIC MAGNETISM: Recent Developments and Perspectives

Annual Review of Astronomy and Astrophysics, 1996

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Research paper thumbnail of Multiscale magnetic fields in spiral galaxies: evolution and reversals

Magnetic fields in nearby, star-forming galaxies reveal both large-scale patterns and small-scale... more Magnetic fields in nearby, star-forming galaxies reveal both large-scale patterns and small-scale structures. A large-scale field reversal may exist in the Milky Way but no such reversals have been observed so far in external galaxies. The effects of star-forming regions of galaxies need to be included when modelling the evolution of their magnetic fields, which can then be compared to

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