New measurements of the mean magnetic field of the sun and its rotation

A list of 152 new measurements of the mean magnetic field (MMF) of the Sun as a star obtained at the Crimean Astrophysical Observatory (CAO) in 1991-1997 are presented. They increase the total number of CAO MMF measurements to N = 1549 (since 1968). This time series is studied together with similar data from the Mount Wilson Observatory (1970-1982, N = 2457). A (synodic) period P-R = 26.95 +/- 0.06 days dominates in the power spectrum of the merged data for 1968-1997, revealing remarkable phase coherence over 30 years. This stability of the rotation of the "magnetic" Sun independent of the Ii-year cycle is difficult to explain in the framework of current theories for the generation of the global solar magnetic field that gives rise to the solar cycle. There are two other periods in the solar MMF (approximate to 161 days and 1.0 year), whose origin is not yet clear.