Thermal Doppler Broadening
In a gas, the individual atoms, elements or molecules are continuously moving in random directions, with an average speed proportional to the temperature of the gas: ...
Doppler Broadening
The smearing of spectral lines because of the motion of atoms in the gas.
Doppler Effect ...
Doppler Broadening
(a) The increase in the width of a spectral line as a result of the motion of the particles emitting or absorbing the radiation. (see Monochromatic Radiation) ...
Thermal Doppler broadening: The atoms in a gas which are emitting radiation will have a distribution of velocities.
THERMAL DOPPLER BROADENING - Spreading of a spectral line due to the temperature of the emitting medium.
Doppler broadening
In atomic physics, Doppler broadening is the broadening of spectral lines due to the Doppler effect in which the heat movement of atoms or molecules shifts the apparent frequency of each emitter....
Doppler broadening (Plasma Physics and Fusion Energy Glossary) Frequency spreading which causes broadening of single-frequency radiation (e.g., spectral lines) when the radiating bodies (atoms, molecules, etc.) have different velocities.
The terrestrial nature of the absorption processes responsible for telluric lines is revealed by their intensity variation with solar zenith angle and by their freedom from any Doppler broadening due to their solar rotation.
A related effect is Doppler broadening of light. Characteristic frequencies or "spectral lines" emitted by atoms usually have very sharply defined wavelengths--but if the light originates in a hot gas, the wavelength range is broadened, ...
An important clue comes from the Doppler broadening of infrared spectral lines emitted from the central swirling whirlpool of gas. The extent of the broadening indicates that the gas is moving very rapidly.
If you can measure σ (perhaps by measuring the Doppler broadening of prominent stellar absorption lines), and can estimate the gravitational radius (not too hard), you can determine the mass.
Profile of a spectral line allowing for the effects of Doppler broadening combined with a Lorentz (damping) profile. [H76]
von Zeipel's Theorem ...
Seyfert galaxies are characterized by extremely bright nuclei, and spectra which have very bright emission lines of hydrogen, helium, nitrogen, and oxygen. These emission lines exhibit strong Doppler broadening, ...
 See also: Energy, Light, Emission, Temperature, Velocity
  
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