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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 ...
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.
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 ]
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]
Highly massive stars (with 25 or more times the mass of the Sun) can lose up to 10 −5 solar masses (M ☉) each year—the equivalent of 1 M ☉ every 100,000 years. [ 8 ] Type Ib and Ic supernovae are hypothesized to have been produced by core collapse of massive stars that have lost their outer layer of hydrogen and helium, either via winds ...
The red color of the chromosphere could be seen during the solar eclipse of August 11, 1999.. The density of the Sun's chromosphere decreases exponentially with distance from the center of the Sun by a factor of roughly 10 million, from about 2 × 10 −4 kg/m 3 at the chromosphere's inner boundary to under 1.6 × 10 −11 kg/m 3 at the outer boundary. [7]
Star formation; Object classes; Interstellar medium; Molecular cloud; Bok globule; Dark nebula; Young stellar object; Protostar; Pre-main-sequence star; T Tauri star; Herbig Ae/Be star; Herbig–Haro object; Theoretical concepts; Accretion; Initial mass function; Jeans instability; Kelvin–Helmholtz mechanism; Nebular hypothesis; Planetary ...
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 ...