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A..2 Bulge Profile
For , Equation 17 becomes de Vaucouleurs, or
, law

(21) 
which characterizes the profiles of elliptical galaxies and bulge components
of disk galaxies. According to this profile, the total brightness can be
written as

(22) 
while the central surface brightness and the average surface
brightness inside the effective radius
are related to
by

(23) 
The bulge profile given by Equation 21 can be put on the more common
logarithmic scale writing

(24) 
where
is the zeropoint of the adopted surface brightness
magnitude scale. Similarly, Equation 22 can be manipulated
so as to express as function of and , obtaining

(25) 
where is the zeropoint of the adopted brightness magnitude scale.
Next: A..3 Disk Profile
Up: A. Galaxy Surface Brightness
Previous: A..1 Sersic Law
Mattia Vaccari
20020131