Astrophysics (Index)About

partial ionization zone

(portion of some stars where gas is partially ionized)

A partial ionization zone is a portion (layer) of some stars where the gas is partly ionized, i.e., on the edge between "gas", and plasma. Added heat, e.g., through compression, is absorbed by the conversion to ions (like heat absorbed by the process of converting liquid water to steam), in this case through the energy necessary to carry out further ionization, i.e., to pull electrons away from their orbits.

In such a zone, added heat can increase opacity (free electrons contribute to opacity), which reduces the outward flow of energy, leading to an unstable situation incompatible with hydrostatic equilibrium. This is can lead to an eventual pulse and is considered one of the phenomena that result in variable stars.

(stars,stellar structure,ionization)
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Referenced by pages:
kappa mechanism (κ-mechanism)