Fig. 9
Panels a–c: Gravity-darkening slope 
against θ defined in Eq. (38) for Υ(θ) = coskθ with k = 0.5, 2.0, 6.0, and α = − 0.5, − 0.25, 0.0 (green lines), +0.25 and +0.5; d)–f) same, but for Υ(θ) = sinkθ and α′ = + 1.0, + 1 / 3, 0.0 (green lines), − 1 / 5 and − 1 / 3; g)–i) as from (a) to (c), but for the term 
; j)–l) as from (d) to (f), but for the term .
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