convective zone

convective zone

A zone in a star where convection is the main mode of energy transport. This occurs throughout a protostar on the Hayashi track, and beneath the surface of a main-sequence star, where the temperature is sufficiently low to enable the nuclei of hydrogen and heavier elements to recombine with free electrons to form atoms and negative ions. The presence of these atoms and ions and their ability to absorb photons increases the opacity of the medium to the passage of radiation from below and results in a steeper temperature gradient, thereby triggering turbulent convection. Stars rather more massive than the Sun, fusing hydrogen by the carbon cycle, have a convective zone at the core, which mixes the nuclear fusion region.

The surface convective zone of a sunlike or late-type star is almost certainly involved in the production of its magnetic field, and hence in the cycle of chromospheric activity (or in the Sun's case solar activity) and in the heating of the chromosphere and corona, but the details are still uncertain. See also granulation; stellar structure.

convective zone

[kən′vek·div ‚zōn]
(astrophysics)
A region of instability just below the photosphere of the sun in which part of the heat is carried outward by convective currents.
References in periodicals archive ?
The presence of g-mode pulsations in B-type post main sequence stars has been explained by a partial reflection of some modes at an intermediate convective zone related to the hydrogen shell burning or at chemical gradient zone surrounding the radiative core.
In the outermost 30 percent of the sun, known as the convective zone, rising plasma carries heat generated by nuclear fusion in the sun's guts.
These surfaces will eventually increase in temperature enough to allow heat to be transferred by convection to the air, thereby contributing to the convective zone cooling load.
Granules are small cells of magnetically charged plasma bubbling up from the Sun's convective zone into the photosphere.
Our data clearly illustrates that the Sun can generate magnetic fields not only as previously known in the convective zone but also on the near-surface layer.
These are low rotation velocity stars so they are not well-mixed, and the normal He II convective zone is suppressed.
The salt-gradient solar pond is generally consists of three distinct zone namely an upper convective zone (UCZ), a non convective zone (NCZ) and a lower convective zone (LCZ).
The extent of the convective zone then grows towards the envelope of the star, as mass increases.
In the case of Benard convection, the number of generated Benard cells in a convective zone is apparently not limited, since convective zones can have astronomical lifetimes.
Doing so revealed on unexplained fluctuations in the decay rates - ones that the researchers said were caused by the rotation of Sun's radiative zone, which is the region between the core and the convective zone, and of the solar core.
According to current theories, the Sun's magnetic field originates along the boundary between the radiative zone deep inside, where material is motionless and heat makes its way upward only by radiation, and the convective zone extending from there to the surface, where material circulates up and down as if boiling.

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