emissionmass

Emissionmass is a term used to describe the mass-equivalent carried away from a system by radiative emission, based on mass-energy equivalence. It is not a standard constant in physics, but a derived quantity used to quantify how much mass is effectively lost through radiation over time. The concept treats the energy emitted as corresponding to a loss of mass M_emission, since E = mc^2.

Definition and calculation: The emissionmass at a given time can be defined as M_emission(t) = ∫ L_rad(t') / c^2 dt' over a chosen interval, where L_rad is the radiated luminosity and c is the speed of light. In a system with approximately constant luminosity L, the instantaneous mass-loss rate is ṁ_em = L / c^2, and the total emissionmass over a time Δt is M_emission = (L / c^2) Δt.

Context and applications: Emissionmass is relevant in astrophysical contexts where radiation carries away a significant portion of a system’s mass-energy, such as stars with strong radiative winds, accreting compact objects, and explosive events where neutrinos and photons escape. It complements other mass-loss accounting by focusing on the energy carried away by radiation, and it can be compared with observed wind or jet masses to assess the relative importance of radiative loss.

Limitations: Emissionmass accounts only for the mass-energy carried away by emitted radiation and not necessarily for all mass-loss channels. Its value depends on the chosen time window and the measured luminosity. In many systems, other processes (winds, outflows, disruptions) contribute substantially to total mass loss.

Example: The Sun’s luminosity implies a radiative mass-loss rate of about 4 × 10^9 kg/s, roughly 6 × 10^-14 solar masses per year. See also mass loss, energy-mass equivalence, Eddington luminosity.