Core-to-Envelope Rotation from Mixed-Mode Splittings: Converting Kepler Splittings into Rotation Periods and a Contrast Bound

Rotation splits each oscillation mode into components whose separation reports the spin of the layers the mode samples. This paper computes, from stated assumptions and published stellar values, a quantitative budget for rotational splitting using published Kepler red-giant core and envelope splittings. The headline results are: P core 06 = 19.3; P env 01 = 116; contrast = 6.0; P 04 = 28.9. Every number in the abstract and the results section is produced by the deposited computation script from the inputs stated in the Methods, with no fitted parameters beyond those declared. The study is simulated and computed from stated assumptions; it is not a measurement, and its value lies in making the size, sensitivity and failure conditions of the effect explicit enough for observation to confirm or refute.