In physics and in particular in the theory of magnetism, an antidynamo theorem is one of several results that restrict the type of magnetic fields that may be produced by dynamo action.
One notable example is Thomas Cowling's antidynamo theorem which states that no axisymmetric magnetic field can be maintained through a self-sustaining dynamo action by an axially symmetric current.[1] Similarly, the Zeldovich's antidynamo theorem states that a two-dimensional, planar flow cannot maintain the dynamo action.[2]
Consequencesedit
Apart from the Earth's magnetic field, some other bodies such as Jupiter and Saturn, and the Sun have significant magnetic fields whose major component is a dipole, an axisymmetric magnetic field. These magnetic fields are self-sustained through fluid motion in the Sun or planets, with the necessary non-symmetry for the planets deriving from the Coriolis force caused by their rapid rotation, and one cause of non-symmetry for the Sun being its differential rotation.[1]
The magnetic fields of planets with slow rotation periods and/or solid cores, such as Mercury, Venus, and Mars, have dissipated to almost nothing by comparison.
The impact of the known anti-dynamo theorems is that successful dynamos do not possess a high degree of symmetry.
antidynamo, theorem, physics, particular, theory, magnetism, antidynamo, theorem, several, results, that, restrict, type, magnetic, fields, that, produced, dynamo, action, notable, example, thomas, cowling, antidynamo, theorem, which, states, that, axisymmetri. In physics and in particular in the theory of magnetism an antidynamo theorem is one of several results that restrict the type of magnetic fields that may be produced by dynamo action One notable example is Thomas Cowling s antidynamo theorem which states that no axisymmetric magnetic field can be maintained through a self sustaining dynamo action by an axially symmetric current 1 Similarly the Zeldovich s antidynamo theorem states that a two dimensional planar flow cannot maintain the dynamo action 2 Consequences editApart from the Earth s magnetic field some other bodies such as Jupiter and Saturn and the Sun have significant magnetic fields whose major component is a dipole an axisymmetric magnetic field These magnetic fields are self sustained through fluid motion in the Sun or planets with the necessary non symmetry for the planets deriving from the Coriolis force caused by their rapid rotation and one cause of non symmetry for the Sun being its differential rotation 1 The magnetic fields of planets with slow rotation periods and or solid cores such as Mercury Venus and Mars have dissipated to almost nothing by comparison The impact of the known anti dynamo theorems is that successful dynamos do not possess a high degree of symmetry See also editDynamo theory Magnetosphere of Jupiter Magnetosphere of SaturnReferences edit a b Cowling T G 1934 The magnetic field of sunspots Monthly Notices of the Royal Astronomical Society 94 39 48 Bibcode 1933MNRAS 94 39C doi 10 1093 mnras 94 1 39 Zeldovich Y B 1957 The magnetic field in the two dimensional motion of a conducting turbulent fluid Sov Phys JETP 4 460 462 nbsp This geophysics related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Antidynamo theorem amp oldid 1127023994, wikipedia, wiki, book, books, library,
