Upper limit on solar interior rotation

Abstract

The power spectrum of solar total irradiance (flux) variations front the Active Cavity Radiometer Irradiance Monitor (ACRIM) on the Solar Maximum Mission (SMM) spacecraft shows individual 5-min p- mode oscillations ^1,2of spherical harmonic degree l= 0–2 and radial order n= 16–26. An m-state splitting analysis based on the widths of the (n,l) multiplets in the spectrum of ACRIM data yields a mean (sidereal) interior rotation rate between 0 and 2.2 times the observed 0.456- µHz equatorial surface rate, consistent with the rapid rotation rate originally claimed by Claverie et al.³based on a (controversial) splitting interpretation of the these 5-min modes seen in line-of-sight velocity. Rotationally split p- and g- and f-modes have been identified in the temporal power spectrum of the limb-darkening data of Bos and Hill⁴, and from these splittings two internal rotation curves^5,6 have been deduced which imply a solar gravitational quadrupole moment J₂large enough to spoil the precise agreement between general relativity and observations of planetary motion. The splitting of the low- l 5-min p- modes implied by these curves is inconsistent with the upper limit derived here, and the reported conflict with einsteinian theory, is therefore, premature.