منابع مشابه
Problems and Progress in Astrophysical Dynamos
Astrophysical objects with negligible resistivity are often threaded by large scale magnetic fields. The generation of these fields is somewhat mysterious, since a magnetic field in a perfectly conducting fluid cannot change the flux threading a fluid element, or the field topology. Classical dynamo theory evades this limit by assuming that magnetic reconnection is fast, even for vanishing resi...
متن کاملMagnetic Helicity Conservation and Astrophysical Dynamos
We construct a magnetic helicity conserving dynamo theory which incorporates a calculated magnetic helicity current. In this model the fluid helicity plays a small role in large scale magnetic field generation. Instead, the dynamo process is dominated by a new quantity, derived from asymmetries in the second derivative of the velocity correlation function, closely related to the ‘twist and fold...
متن کاملChandrasekhar–Kendall functions in astrophysical dynamos
Some of the contributions of Chandrasekhar to the field of magnetohydrodynamics are highlighted. Particular emphasis is placed on the Chandrasekhar–Kendall functions that allow a decomposition of a vector field into rightand left-handed contributions. Magnetic energy spectra of both contributions are shown for a new set of helically forced simulations at resolutions higher than what has been av...
متن کاملHow Astrophysical Mean Field Dynamos Can Circumvent Existing Quenching Constraints
Mean field dynamo theory is a leading candidate to explain the large scale magnetic flux in galaxies and stars. However, controversy arises over the extent of premature quenching by the backreaction of the growing field. We distinguish between rapid dynamo action, which is required by astrophysical systems, and resistively limited dynamo action. We show how the flow of magnetic helicity is impo...
متن کاملCoronal Activity as a Consequence of Dynamos in Astrophysical Rotators
We show that the presence of a steady α-Ω dynamo in astrophysical rota-tors likely leads to an outflow of relative magnetic helicity and thus magnetic energy available for particle acceleration in a corona. The connection between energy and magnetic helicity arises because the generation of large scale field is linked to a generation of large scale magnetic helicity. In a steady state, the rela...
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ژورنال
عنوان ژورنال: Nature
سال: 1980
ISSN: 0028-0836,1476-4687
DOI: 10.1038/285016a0