Continuum and line opacity mechanisms
Stellar opacity includes electron scattering, bound–bound transitions, photoionization/recombination and free–free processes.
Key knowledge
Stellar opacity includes electron scattering, bound–bound transitions, photoionization/recombination and free–free processes. The attenuation coefficient α_ν=ρκ_ν converts mass opacity to inverse length. Their relative contributions depend on frequency, composition, ionization and temperature; one gray opacity cannot generally represent a resolved spectrum.
Values and equations
α_ν=ρκ_ν; κ_es=nₑσ_T/ρ
- α_ν
- attenuation coefficient m⁻¹
- ρ
- total mass density kg m⁻³
- κ_ν,κ_es
- frequency-dependent and electron-scattering mass opacity m² kg⁻¹
- nₑ
- free-electron number density m⁻³
- σ_T
- Thomson electron cross section m²
Conditions and scope
- κ_ν is defined per total material mass, with a consistent absorption/scattering convention.
- For electron scattering, κ_es=nₑσ_T/ρ in the low photon-energy Thomson regime; energy-changing high-energy scattering needs another model.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read the four opacity classes and density normalization equations170–174. Converted cgs dimensions to SI; omitted dated approximate numerical cross sections and detailed opacity-table claims.
2026-10-10 · Independent AI editorial review: All44 exact root-authored compact records, equations/variable units/conditions and140 origin edges accepted after independently reading final6/18 with bounded primary bodies and matching prior38/122 scientific fingerprints unchanged. Exact claim/edge review is distinct from combined inventory scope and separate CLE26 approval; no entire cited books or old-corpus experimental revalidation is asserted. Receipt: cosmos-completion-independent-content-and-inventory-review.1.
Entry details
Permanent link to this entry ↗- Record identity
- uni-cosmos-continuum-line-opacity
- Revision
- core.1
- Structured reference record
- University core expansion