An Etymological Dictionary of Astronomy and Astrophysics
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A model concerned with the distribution in size of → interstellar grains to account for observations of → interstellar extinction from 0.11 μm to 1.0 μm. The → distribution has the form N(a)da ∝ a^-3.5da, where a is the grain radius. It extends from 5 nm to 1 μm for → graphite and over a narrower range for other materials.

MNR, the initials of authors J. S. Mathis, W. Rumpl, and K. H. Nordsiek (1977, ApJ 217, 425), who introduced the mode; → dust; → model.