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The simplest commonly used model of stellar structure is the spherically symmetric quasi-static model, which assumes that a star is in a steady state and that it is spherically symmetric. It contains four basic first-order differential equations : two represent how matter and pressure vary with radius; two represent how temperature and ...
The radius of the radiative zone increases monotonically with mass, with stars around 1.2 solar masses being almost entirely radiative. Above 1.2 solar masses, the core region becomes a convection zone and the overlying region is a radiative zone, with the amount of mass within the convective zone increasing with the mass of the star. [7]
The molecular layer is cool enough to contain molecules rather than plasma, and may consist of such components as carbon monoxide, water vapor, silicon monoxide, and titanium oxide. The outermost part of the stellar atmosphere, or upper stellar atmosphere, is the corona , a tenuous plasma which has a temperature above one million Kelvin. [ 6 ]
An illustration of the structure of the Sun and a red giant star, showing their convective zones. These are the granular zones in the outer layers of the stars. A convection zone, convective zone or convective region of a star is a layer which is unstable due to convection.
Coronal stars are ubiquitous among the stars in the cool half of the Hertzsprung–Russell diagram. [25] These coronae can be detected using X-ray telescopes. Some stellar coronae, particularly in young stars, are much more luminous than the Sun's. For example, FK Comae Berenices is the prototype for the FK Com class of variable star. These are ...
The expanding outer layers of the star are convective, with the material being mixed by turbulence from near the fusing regions up to the surface of the star. For all but the lowest-mass stars, the fused material has remained deep in the stellar interior prior to this point, so the convecting envelope makes fusion products visible at the star's ...
The photosphere is that portion of a star that is visible to an observer. This is the layer at which the plasma of the star becomes transparent to photons of light. From here, the energy generated at the core becomes free to propagate into space. It is within the photosphere that sun spots, regions of lower than average temperature, appear. [204]
Curvature modes exist in all relativistic stars and are related to the spacetime curvature. Models and numerical studies [9] suggest an unlimited number of these modes. Interface modes or wII-modes [10] are somewhat similar to acoustic waves scattered off a hard sphere; there seems to be a finite number of these modes. They are rapidly damped ...