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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. Energy is primarily or partially transported by convection in such
For example, in the Sun the convection at the base of the convection zone, near the core, is adiabatic but that near the surface is not. The mixing length theory contains two free parameters which must be set to make the model fit observations, so it is a phenomenological theory rather than a rigorous mathematical formulation.
The Sun is composed primarily of the chemical elements hydrogen and helium; they account for 74.9% and 23.8%, respectively, of the mass of the Sun in the photosphere.All heavier elements, colloquially called metals in stellar astronomy, account for less than 2% of the mass, with oxygen (roughly 1% of the Sun's mass), carbon (0.3%), neon (0.2%), and iron (0.2%) being the most abundant.
A star's magnetic field can be measured using the Zeeman effect. Normally the atoms in a star's atmosphere will absorb certain frequencies of energy in the electromagnetic spectrum, producing characteristic dark absorption lines in the spectrum. However, when the atoms are within a magnetic field, these lines become split into multiple, closely ...
The stellar atmosphere is the outer region of the volume of a star, lying above the stellar core, radiation zone and convection zone. Overview The stellar atmosphere ...
The tachocline is the transition region of stars of more than 0.3 solar masses, between the radiative interior and the differentially rotating outer convective zone. This causes the region to have a very large shear as the rotation rate changes very rapidly.
Above this spherical radiation zone lies a small convection zone just below the outer atmosphere. At lower stellar mass , the outer convection shell takes up an increasing proportion of the envelope, and for stars with a mass of around 0.35 M ☉ (35% of the mass of the Sun) or less (including failed stars ) the entire star is convective ...
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 these stars. The convection zone of a star is the range of radii in which energy is transported outward from the core region primarily by convection rather than radiation.