Stellar opacity

Stellar opacity measures how strongly matter inside a star absorbs or scatters radiation. It controls how readily energy moves outward through the star.

Radiative transfer: The physical description of how radiation is emitted, absorbed, and scattered as it travels through matter. Opacity sets how radiation changes while crossing stellar material.
Thomson scattering: Elastic scattering of electromagnetic radiation by free, nonrelativistic charged particles, especially electrons. It supplies an important nearly frequency-independent opacity in hot ionized stellar interiors.
Stellar structure: The internal organization of a star, described by its pressure, temperature, density, and energy flow. Opacity enters the equations that determine how these quantities vary with radius.
Arthur Stanley Eddington: British astrophysicist who developed influential theories of stellar structure and radiation pressure. His early stellar models made opacity central to calculating energy transport.
Solar abundance problem: The mismatch between solar interior models using revised element abundances and helioseismic measurements. Increasing opacity near the base of the solar convection zone could reduce this mismatch.
Rosseland mean opacity: A frequency-averaged opacity weighted for radiative diffusion in optically thick matter. Stellar structure models use it to describe diffusion across a range of photon frequencies.
Bound-free transition: A photon-driven transition that ionizes a bound electron or allows a free electron to be captured by an ion. These transitions create strong opacity across many stellar temperatures and frequencies.
Stellar evolution: The changes in a star's structure and observable properties over its lifetime. Opacity tables help determine how stars change as their composition and internal conditions evolve.
Cecilia Payne-Gaposchkin: Astronomer whose work established that stars are composed mainly of hydrogen and helium. Her abundance results helped clarify which elements contribute to stellar opacity.
Helioseismology: The study of the Sun's interior using its observed oscillations. Its precise structural constraints expose tensions between predicted and required solar opacity.

Linked from 5 pages