251, 252] 
Solar Rotation 
283 
Sidereal Rotation Period in Days 
If we attempt to interpret these formulae in terms of the extended Roche’s 
model, a comparison with formula (251'4) shews that the observed equatorial 
acceleration of the sun’s rotation would require the inner core to have an 
eccentricity e such that e 2 /(l — e 2 ) = 0T5 or e = 036. The ratio of its axes is 
given by b — 0\93 a. To produce this degree of ellipticity in a core of uniform 
Reversing Layer (Adams) <p = 14° - 54 - 3°*50 sin 2 \ 
Calcium Flocculi (Fox) <p =14°-56 - 2 0, 98 sin 2 X 
„ , 4 (¿ = 14 0, 49 -1°*78 sin 2 X - 3° - 16 sin 4 X ..... . 
Faculae (Greenwich) ^ = 14 °-54 - 2°-81 sin 2 X 
Faculae (Chevalier) <f> = 14°*47 - 2°-27 sin 2 X - • - • - 
Spots (Maunder) 0 = 14 0, 43 - 2°-13 sin 2 X - 
density p, o) 2 /27T7p must be equal to 0’035. The value of to 2 /27 ryp for the sun’s 
outer surface is only 0‘000014, so that if the sun’s equatorial acceleration is 
to be explained in terms of this model, the angular velocity of the core must 
be very much greater than that of the surface. If the law <j> oc 1/r 2 is obeyed, 
the core must be of small radius or, alternatively, <f> may increase much more 
rapidly than 1/r 2 in the central regions of the sun.