Related papers: Planetary dynamos
The magnetic fields of terrestrial planets are generated in their liquid cores through dynamo action driven by thermal and compositional convection. The coexistence of these two buoyancy sources gives rise to double-diffusive convection…
Recent spectro-polarimetric observations of solar-type stars have shown the presence of photospheric magnetic fields with a predominant toroidal component. If the external field is assumed to be current-free it is impossible to explain…
Planetary and stellar magnetic fields are thought to be sustained by helical motions ($\alpha$-effect) and, if present, differential rotation ($\Omega$-effect). In the Sun, the strong differential rotation in the tachocline is responsible…
We review our current understanding of galactic dynamo theory, paying particular attention to numerical simulations both of the mean-field equations and the original three-dimensional equations relevant to describing the magnetic field…
Thermal convection is commonly believed to be the energy source of stellar or planetary dynamo. In this short paper we provide another possibility, namely large-scale tidal flow. In close binary stars, say, solar-like stars with orbital…
The rapid rotation of planets causes cyclonic thermal turbulence in their cores which may generate the large-scale magnetic fields observed outside the planets. We consider the model which enables us reproduce the typical features of…
The prevailing theory for the origin of cosmic magnetic fields is that they have been amplified to their present values by the turbulent dynamo inductive action in the protogalactic and galactic medium. Up to now, in calculation of the…
The observed galactic magnetic fields may have a primordial origin. I briefly review the observations, their interpretation in terms of the dynamo theory, and the current limits on cosmological magnetic fields. Several possible mechanisms…
The activity of magnetars is believed to be powered by colossal magnetic energy reservoirs. We sketch an evolutionary picture in which internal field evolution in magnetars generates a twisted corona, form which energy may be released…
The Sun and other cool stars harbouring outer convection zones manifest magnetic activity in their atmospheres. The connection between this activity and the properties of a deep-seated dynamo generating the magnetic flux is not well…
For the understanding of planetary and stellar dynamos an overview of the major parameter dependences of convection driven dynamos in rotating spherical fluid shells is desirable. Although the computationally accessible parameter space is…
Planetary magnetic fields are important indicators of planetary processes and evolution, from a planet's outer core to its surface (if it possesses one) to its atmosphere and near-space environment. Magnetic fields are most directly…
Convection is a fundamental physical process in the fluid cores of planets because it is the primary transport mechanism for heat and chemical species and the primary energy source for planetary magnetic fields. Key properties of…
Precession has been proposed as an alternative power source for planetary dynamos. Previous hydrodynamic simulations suggested that precession can generate very complex flows in planetary liquid cores [Y. Lin, P. Marti, and J. Noir,…
The origin and maintenance of large scale magnetic fields in the Universe is discussed. A popular idea is that cosmic batteries generate seed magnetic fields which were amplified by magnetic induction due to turbulent motions, at times…
In this review, I will summarise what we know about magnetic fields in stars and what the origin of these magnetic fields may be. I will address the issue of whether the magnetic flux is conserved from pre-main sequence to the compact star…
Magnetic fields remain one of the least understood aspects of exoplanetary systems. A deeper understanding of planetary dynamos and the evolution of surface magnetic properties throughout a planet's lifetime is a key scientific purpose,…
Tangent Cylinders (TCs) have shaped our understanding of planetary dynamos and liquid cores. The Taylor-Proudman Constraint (TPC) due to planetary rotation creates these imaginary surfaces separating polar and equatorial regions but cannot…
We discuss possible mechanisms underlying the observed features of stellar activity cycles, such as multiple periodicities in very active stars, non-cyclic activity observed in moderately active stars, and spatial distribution of stellar…
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…