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.
In 1968, scientists theorized that even longer-lived and larger convection cells, big enough to span the entire convective zone, maintain the fast rotation researchers had long observed around the sun's equator; without such cells, the poles should rotate faster than the equator.
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.
3]) currently proposed for the convective zone and the photosphere ([10.
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.
Nevertheless, the formation of Benard cells in the convective zone is a process supplied with energy by the energy inflow.
Helioseismology -- observations of the way the sun's surface rises and falls in a pattern of oscillations -- provides one of the best checks on these nonstandard models by supplying information about the sun's internal structure, for example, how deep the sun's convective zone goes.

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