Pure power-law density profiles, #92;rho(r)#92;proptor#123;b-3#125;, are classified in connection with the following reference cases: (i) isodensity, b#61;3, #92;rho#61; const; (ii) isogravity, b#61;2, g#61; const; (iii) isothermal, b#61;1, v#61;#91;GM(r)#47;r#93;#123;1#47;2#125;#61; const; (iv) isomass, b#61;0, M#61; const.
Source: wiktionary