The Latitudinal Distribution of Solar Sound Speed

Sarbani Basu

The solar sound-speed distribution is not spherically symmetric. The figure shows the relative deviation from the spherically-symmetric sound-speed profile. The results are reliable between depths of 0.5 and 0.95 Rsun. In the deeper layers of the convection zone, sound-speed can be directly related to temperature, and thus the figure shows that the equatorial and lower-latitude regions of the Sun are cooler than the higher latitudes. This result is contrary to what is expected from theoretical studies and simulations. The results appear to show a cooler pole, however, the results are not reliable at very high latitudes. These results were obtained by analyzing helioseismic data obtained by the Michelson Doppler Imager (MDI) on board the SOHO spacecraft