The Sun's Seismic Radius as Measured from the Fundamental Modes of Oscillations and Its Implications for the TSI Variations
Kiran Jain, S. C. Tripathy, F. Hill
2018
Astrophysical Journal Letters
In this letter, we explore the relationship between the solar seismic radius and total solar irradiance (TSI) during last two solar cycles using the uninterrupted data from space-borne instruments onboard SoHO and SDO. The seismic radius is calculated from the fundamental ( f) modes of solar oscillations utilizing the observations from SoHO/MDI and SDO/HMI, and the total solar irradiance measurements are obtained from SoHO/VIRGO. Our study suggests that the major contribution to the TSI
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... n arises from the changes in magnetic field while the radius variation plays a secondary role. We find that the solar irradiance increases with decreasing seismic radius, however the anti-correlation between them is moderately weak. The estimated maximum change in seismic radius during a solar cycle is about 5 kilometers, and is consistent in both solar cycles 23 and 24. Previous studies suggest a radius change at the surface of the order of 0.06 arcsecond to explain the 0.1% variation in the TSI values during the solar cycle, however our inferred seismic radius change is significantly smaller, hence the TSI variations can not be fully explained by the temporal changes in seismic radius.
doi:10.3847/2041-8213/aac327
fatcat:d22dreww7zcapnf26g2rn5d5a4