for Ca+ on the basis of a maximum at
, assumed temperature 4500°. This is the effective temperature of the class, deduced spectrophotometrically, and “the reversing layer should be at a lower temperature—its average temperature should be in the neighborhood of, or somewhat lower than, the Schwarzschild boundary temperature,[[iv]] which is some 15-20 per cent lower than the effective temperature.” The value 4000° is therefore adopted here for
. For this value
becomes
for Ca+; for Sr+ (