An Etymological Dictionary of Astronomy and Astrophysics
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Pressed into less space; condensed.

Past participle of → compress.

Air whose density is increased by being subjected to a pressure greater than atmospheric pressure.

→ compressed; → air.

The ability or quality to be reduced in volume. The coefficient of compressibility of a substance is given by c = (1/V).(δV/δp), where δV is the change in the volume resulting from a change of pressure δp, the temperature remaining constant.

Noun from → compressible.

Able to be reduced in volume. → compressible flow.

Adjective from → compress + -ible, variant of -able.

Tanjidani, tanješpazir from tanjidan, → compress, + adjective suffix -i; tanješpazir from tanješ, → compression, + pazir "receiving, admitting; having, endowed with;" → -able.

A flow in which changes of the density, induced by velocities and their fluctuations, are not negligible.

→ compressible; → flow.

The act or process of compressing; the state of being compressed.

Verbal noun from → compress.

In thermodynamics, the quantity Z = pV_m/RT, in which P is the gas pressure, V_m the molar volume, R the gas constant, and T the temperature. The compression factor is a measure of the deviation of a real gas from an ideal gas. For an ideal gas the compression factor is equal to 1.

→ compression; → facteur.

A → longitudinal wave that compresses the → medium along the direction of → propagation, such as a → sound wave. Same as → compressional wave.

→ compression; → wave.

Of or relating to → compression.

→ compression; → -al.

An → elastic wave that travels through a → medium with the particles of the medium moving in the same direction as the wave propagation. The compressional wave is the wave that is primarily used in → seismic exploration. Also called P-wave, primary wave, pressure wave.

→ compressional; → wave.

The American physicist Arthur Holly Compton (1892-1962), the Nobel Prize in Physics 1927, who made important contributions to the study of X- and cosmic rays.
→ Compton catastrophe, → Compton effect, → Compton equation, → Compton era, → Compton recoil, → Compton scattering, → Compton shift, → Compton suppression, → Compton wavelength, → Comptonization.

In a compact, steady radio-source where the density of relativistic electrons and the density of synchrotron radiation due to these electrons are very large, the radio photons should be transformed into X-ray and gamma-ray photons through inelastic Compton scatterings onto the relativistic electrons. Thus the radio photons should rapidly disappear and only gamma-ray photons should be observed. This phenomenon does not take place if the radio source is in relativistic expansion.

→ Compton; → catastrophe.

Increase in the wavelength of an → X-ray or → gamma ray  → photon when it collides a → free → electron. The photon transfers part of its energy to the electron, the electron recoils, and the photon itself is scattered at a reduced energy.

→ Compton; → effect.

Theoretical equation which gives the change in the photon wavelength due to the → Compton effect.

→ Compton; → equation.

A period in the early evolution of the Universe, before t = 10^-23 sec when the radius of curvature of the Universe was less than the → Compton wavelength of typical particles.

→ Compton; → era.

The change of direction undergone by the electron in the → Compton effect. The scattered photon and the collided electron move in different directions from that of the incident photon.

→ Compton; → recoil.

Scattering of a → photon due to the → Compton effect.

→ Compton; → scattering.

Of the → Compton effect, the amount of increase in the wavelength of an energetic photon upon its collision with an electron.

→ Compton; → shift.

In → gamma ray → spectroscopy, a technique to reduce the contribution of gamma rays generated by → Compton scattering.

→ Compton; → suppression.

The quantum wavelength of a particle with a highly relativistic velocity. The Compton wavelength is given by h/mc, where h is Planck's constant, m is the mass of the particle, and c the light speed. For an electron, the Compton wavelength is about 2.4 × 10^-10 cm, intermediate between the size of an atomic nucleus and an atom.

→ Compton; → wavelength.