Measurement of the Rotation Rate
in the Deep Solar Interior

S. Tomczyk,
High Altitude Observatory, NCAR,
P.O. Box 3000, Boulder, CO 80307

J. Schou,
Center for Space Physics and Astrophysics, HEPL Annex 201,
Stanford University, CA 94305

M. J. Thompson
Astronomy Unit, Queen Mary and Westfield College,
Mile End Road, London E1 4NS, UK

Abstract. We present a measurement of solar internal rotation based on observations obtained over 3 months in early 1994 with a new instrument called LOWL. This instrument allows for the simultaneous observation of low- and intermediate-degree solar oscillations with spatial resolution. We have measured the frequency splitting of 673 multiplets with degrees ranging from 1 to 80, and inverted these to derive an estimate of the solar internal rotation profile between 0.2 and 0.85 solar radii. The accuracy of this measurement ranges from about 1% in the outer regions to about 5% at 0.2 solar radii and thus places better constraints than hitherto on the rotation in the deep solar interior. 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 from the base of the convection zone down to 0.2 solar radii our measurement is consistent with rigid body rotation at a rate somewhat lower than the surface equatorial rate. The accuracy of our measurement in the deep solar interior provides a strong constraint to theories of solar and stellar angular momentum transport.

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