An Etymological Dictionary of Astronomy and Astrophysics
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The polarization of starlight caused by aligned → interstellar grains, so that initially → unpolarized light from a star is partially polarized by the time it reaches the Earth.

→ interstellar; → polarization.

A global ionizing radiation in the → interstellar medium provided by various sources all together.

→ interstellar; → radiation; → field.

The dimming of light during its travel in the → interstellar medium due to absorption by → intervening → dust grains. Since shorter wavelengths are particularly affected, the spectrum of the light is increasingly dominated by the long wavelength end of the spectrum. As a result, the light is "reddened" as it travels through space. Robert J. Trumpler (1886-1956), a Swiss-American astronomer, was the first to produce a definite evidence of the existence of → interstellar extinction and to estimate its magnitude (1930).

→ interstellar; → reddening.

A graph showing the relation between → interstellar absorption (in magnitudes) and wavelength.

→ interstellar; → reddening; → curve.

An apparent twinkling of the signals from distant point-like radio sources (pulsars). It is due to turbulence, i.e. fluctuations in the electron density of the interstellar ionized gas, through which the signals have passed on their way to Earth.

→ interstellar; → scintillation.

An → interstellar cloud that surrounds the → heliosphere.

→ local; → interstellar; → cloud.

A description of the interstellar medium justified by the presence of supersonic shock waves, massive star winds, turbulence, supernova explosions, etc.

→ violent; → interstellar; → environment.