Hubble–Reynolds law

The Hubble–Reynolds law models the surface brightness of elliptical galaxies as

Where I ( R ) is the surface brightness at radius R , I 0 is the central brightness, and R H is the radius at which the surface brightness is diminished by a factor of 1/4. It is asymptotically similar to the De Vaucouleurs' law which is a special case of the Sersic profile for elliptical galaxies.

The law is named for the astronomers Edwin Hubble and John Henry Reynolds.