The term Emission is used in the study of Radiative Transfer (RT) and Spectroscopy to mean the addition of photons to a beam of Electromagnetic Radiation (EMR) (e.g., light), from changes in atoms, and from scattering. It is the inverse of Absorption, the removal of photons to the beam. The concept is used widely in astrophysics, for explaining and modeling stars, for dealing with the effects of the Earth's Atmosphere, for explaining and modeling gas clouds, etc. Each type of Absorption has an Emission inverse, or if it is Scattering, is both absorption and emission, thus the classification of absorption processes also is a possible classification of emission processes.
Spontaneous Emission is the emission of a photon by an atom not from any immediate interaction, e.g., the emission of a photon when an atom a lower level of Atomic Excitation, e.g., when an electron moves to a lower orbit.
Active Galactic Nucleus (AGN)
Alpha CO (αCO)
Emission Line Galaxy (ELG)
Emission Coefficient (j)
GALEX Arecibo SDSS Survey (GASS)
Galactic All-Sky Survey (GASS)
Radiative Transfer (RT)
Radiative Transfer Code (RT Code)
Equation of Radiative Transfer (RTE)
Radiative Transfer Model (RTM)
Star Formation Rate (SFR)
State of Excitation
Tully-Fisher Relation (TFR)