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Session 69 - The Solar Dynamo and Helioseismology.
Display session, Thursday, June 13
Tripp Commons,

[69.03] Measurement of the Rotation Rate in the Deep Solar Interior

S. Tomczyk (HAO/NCAR), J. Schou (Stanford Univ.), M. J. Thompson (Queen Mary and Westfield College)

We present a measurement of the rotation rate in the interior of the Sun based on two years of observations with the LOWL instrument. LOWL allows the observation of solar oscillations with degrees from 0 to 100, thus providing a homogeneous low- and intermediate-degree dataset. Significantly, it is able to make spatially resolved observations of low degree modes, thereby making it possible to separate the different modes within a given multiplet. This reduces the potential for systematic errors compared to observations using integrated sunlight. We have used observations of the frequency splittings of modes with degrees from 1 to 100 to infer the rotation rate in the solar interior with some radial resolution and without excessive errors. Over most of the interior we have also been able to estimate the latitudinal variation of the rotation rate. We confirm earlier findings that near the base of the convection zone the solar rotation profile undergoes a transition from surface-like differential rotation to a rotation rate that is independent of latitude. Additionally, we find that below the base of the convection zone our measurement is consistent with rigid body rotation at a rate somewhat lower than the surface equatorial rate. This measurement provides strong constraints on the theories of angular momentum transport in solar-type stars.

Program listing for Thursday