Helioseismology (4) ...
Data from SOHO helioseismology have also been used to deduce the internal rotation rate of the Sun.
Internal Rotation Rate of the Sun
The following figure illustrates rotation rates as inferred from solar vibrational data.
The results
are plotted for three different latitudes versus the fraction of the solar radius, and the widths of the
curves indicate the estimated uncertainties in the measurements. The surface velocities at these
latitudes as measured directly by Doppler shifts are indicated by the arrows on the right side of the diagram.
We notice the differential rotation of the Sun near the surface (different latitudes rotating at different rates),
as was already known from surface observations. But
the helioseismology data indicate that inside the convective zone, beginning at about 65 percent of the solar radius,
the Sun begins to
rotate almost as a rigid body. That is, the curves for the three different latitudes converge to similar values,
indicating that all latitudes are rotating with almost the same rate.
