An Etymological Dictionary of Astronomy and Astrophysics

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فرهنگ ریشه‌شناختی اخترشناسی-اخترفیزیک

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reddening parameter
  پارامون ِ سرخش  
pârâmun-e sorxeš
Fr.: paramètre de rougissement  

A dimensionless quantity characterizing the → interstellar extinction, defined by the total-to-selective extinction ratio:
RV = AV/E(B-V). The typical value found for the reddening parameter in the Milky Way is RV ~ 3.1, but it is known to vary from one
line of sight to another, from values as 2 to as large as 6. Very large → dust grains would produce extinction with RV → ∞.

See also: → reddening; → parameter.