reflection nebula

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reflection nebula

A bright cloud of interstellar gas and dust that lies near and somewhat to one side of a star or stellar group, usually of spectral type B2 or later. The starlight is scattered in all directions by the dust grains, the density of which is sufficient to produce a noticeable illumination of the cloud. The light scattered toward the observer is bluer than that of the illuminating star but the spectra of cloud and star are essentially the same – a continuous spectrum with absorption lines. (If there is sufficient dust in an emission nebula, it will cause the stars' absorption spectra to be added to the normal emission spectrum of the nebula.) Reflection nebulosity is characteristic of young clusters and associations; the dust is dispersed in about 100 million years. Typical reflection nebulae occur around the brighter stars of the Pleiades. See also nebula.

reflection nebula

[ri′flek·shən ‚neb·yə·lə]
(astronomy)
A type of bright diffuse nebula composed mainly of cosmic dust; it is visible because of starlight from nearby stars or nebula stars that is scattered by the dust particles.
References in periodicals archive ?
Their variability, in contrast to the unchanging appearance of most reflection nebulae, was thought to arise principally because they happened to be illuminated by variable stars, though in some cases the movement of dust lanes might give rise to added variability, casting transient shadows across regions of space measuring light-months across.
Amateur observations of such reflection nebulae could seek to answer a number of questions.
Prominent among them are M43, directly north of M42 and separated from it by a dark lane--and clearly visible in the same low power field as M42--while slightly further north is a complex area of emission and reflection nebulae commonly known as the Running Man Nebula (NGC 1977).