5.8 Summary of the acoustic-mode results

To summarize, the best evidence we have so far seems to imply that the rotation rate between about 0.2R ⊙ and the base of the convection zone is most likely approximately constant with radius and spherically symmetric. It is not possible to rule out a different rotation rate for the inner core, but there is no evidence from p-mode observations to support such a difference. Between about 0.2R ⊙ and the base of the tachocline, no significant departure from rigid-body rotation has been found. As discussed by Eff-Darwich et al. (2002), for example the available constraints already seem to rule out the simplest models of hydrodynamic spin-down, which would show a detectable increase in the rotation rate below 0.3 R ⊙. Understanding both of the relationship between p mode splittings and the interior rotation, and of the care needed to measure them, has greatly advanced since the early days of helioseismology, but the rotation rate of the innermost nuclear-burning core remains uncertain.
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