HR: 11:45h
AN: SH22B-05    [Abstracts]
TI: Helioseismic Limits on Irradiance Variations
AU: * Goode, P R
EM: pgoode@bbso.njit.edu
AF: Big Bear Solar Observatory/NJIT, 40386 North Shore Lane, Big Bear City, 923 92314 United States
AB: Changes in the frequencies of solar oscillations are the most precise probe of irradiance variations over the solar cycle. Using MDI data, Dziembowski and Goode (2005) showed that f-mode changes arise from the direct effect of the evolving magnetic activity, while p-mode changes are due to small, activity induced changes in convective flows very near to the solar surface (turbulent pressure). The f-modes also sharply limit the allowed field growth with activity, and the limit is consistent with the observations of Lin and Rimmele (1999). Combining MDI data with BBSO Ca II K, we find the Sun is smooth at activity minimum and becomes increasingly corrugated with rising activity. The overall physical picture is one in which the Sun is hottest and smoothest at activity minimum, and becomes cooler, more corrugated and irradiant with rising activity. These results place a lower limit on irradiance variations and are roughly consistent with a picture of Spruit (2000).
DE: 7522 Helioseismology
DE: 7538 Solar irradiance
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2005 Joint Assembly