The longitudinal distribution of solar active regions and solar global oscillation measurements

The recently discovered 13.1-day periodicity in solar global oscillation measurements as reported by Claverie et al. (1982) is shown to be produced by the rotation of active regions occurring predominantly in long lived active longitudes 180° apart. They cause an artificial oscillatory Doppler signal for long periods whenever the solar activity exceeds a critical minimum value (R_M ≥ 40). It is further shown that the properly calibrated active region-weighted Doppler signal for the period July 10 to July 24, 1981 agrees with the measurements of Claverie et al. within the error limits. It is thus concluded that Claverie's observations contain no direct evidence for a fast rotating solar core as was speculated by the authors and by Dicke (1983).