4/3/2023 0 Comments The sun corona diagram![]() The rising part of the granules is located in the center where the plasma is hotter. The motion of photons are still impeded by interactions with the atoms there until they reach the boundary with the photosphere where the convective cells appear as granules. Thus, the criterion for the formation of convective cell is the inequality of the densities environment > bubble (which is equivalent to the stable radiative condition). The reduction in density inside allows the bubble to rise until the heat is released to the cooler environment at the surface and falls back to the bottom without the bubbly appearence (Figure 08-04f). It expends into a spherical volume to equalize the pressure outside. An element of fluid receives heat from the bottom, Convective Zone - Convection occurs every time when we boil water in a pot.In the same diagram, the crosses on the Sun and Red Giant indicate the transition from the convective envelope to the radiative interior as the result of the bending of the steeper slope. The curve for the B1 main sequence star with a mass of 15 M sun in Figure 08-04b clearly violates this radiative equilibrium condition near the core, thus the inner layer becomes convective as shown in Figure 08-04a. In term of the temperature T and pressure P, the criterion for stable radiative layer is : Recent observations suggests that the sheared magnetic field lines in these two regions can account for this long lasting and strong magnetic field about 2000 times stronger than the Earth's (see Figure 08-04c-right, and " NASA's Issue #60 : Where Does The Sun's Magnetic Field Come From ?").įigure 08-04e Radiative Zone ĭepending on the stability of the radiative process, the radiative and convective zones can be arranged differently according to different kinds of stars ( Figure 08-04a). Many theories about the origin of the solar magnetic field have failed to account for its durability. This is the region where solid rotation passes over to differential motion in fluid. On top of this layer is a thin shell called Tachocline. Gamma rays from the core of the Sun to leave the radiation zone (Figure 08-04-left). The photons are absorbed and re-emitted in a slow process, which takes an average of 170,000 years for Radiative Zone - The layer next to the core is the radiative zone where energy is primarily transported toward the exterior by means of radiative diffusion.For massive stars heavier than 15 M sun, more residuals from helium to iron are deposited into the core, those stars are the supergiants.įigure 08-04d Residual Fuel Near the end of the stellar life span, the core becomes the dumping site for the helium byproduct, the nuclear burning occurs in the envelope, and the star turns into a red giant. Reactions involve mainly the p-p chain and CNO cycle (see Figure 08-04c and " Thermo-nuclear Fusion"). It is in the inner most 30% of the radius (for Sun-like star). Core - This is the region where energy is generated.Stellar structure can be roughly divided into six zones according to some characteristics : Table 08-01 Characteristics of Main-Sequence Stars Table 08-01 below lists some characteristics of main-sequence stars as the function of mass. The crosses on the Sun and Red Giant indicate the transition from the convective layer to the radiative zone.įigure 08-04b Density-Temperature Diagram The dotted line separates two different kinds of opacity (electron scattering in the upper portion, bound-free/free-free transitions below). ![]() ![]() The dashed lines represent transitions in the equation of state. The four intermediate points divide the star into five zones of equal mass. In the diagram, each line represents a star starting at the right with a point for the center and ending at the left with another point for the photosphere. Information by plotting the variation of temperature and density for four different types of stars. However, the diagram in Figure 08-04b conveys a little bit more The structure of stars can be illustrated by a pictures, which divide the body into zones as shown in Figure 08-04a and will be described in the followings for each zone within a typical star like the Sun.
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