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Session 49 - First Results from the Solar and Heliospheric Observatory (SOHO).
Oral session, Tuesday, June 11
Wisconsin Center,

[49.02] Helioseismology from SOHO

J. T. Hoeksema (Stanford Univ.)

Three instruments on SOHO continuously measure the solar oscillations that reveal the internal structure and dynamics of the nearest star. Interpretation of helioseismology data will provide a nearly complete picture of the composition, temperature, density, rotation, and circulation patterns from the convection zone to the energy generating core, and their variations with time.

Oscillation modes with larger spatial scales penetrate deeper into the solar core. GOLF (full disk) and VIRGO (12 pixels) measure down to the central core by detecting photospheric changes in velocity and intensity, respectively. Analyses of 1024x1024 MDI velocity and intensity images are more sensitive to conditions near the surface. GOLF and MDI also measure magnetic field; components of VIRGO measure irradiance in several wavelengths as well as the solar constant.

The instruments have been commissioned and are producing new results already. The lack of atmospheric distortions and diurnal variations have lowered the estimates of solar background noise levels. As the time series lengthen, we will learn more about the relationships between surface and subsurface flows and the magnetic field, about the emergence and development of solar active regions, about the causes and effects of the solar cycle, and about the details of conditions and processes acting in the solar core.

This research is supported by the SOI-MDI NASA contract NAG5-3077 at Stanford University.

Program listing for Tuesday