Helioseismic evidence of two solar granulation timescales

Abstract

The signature of two different scales of solar granulation in the power spectrum of disk integrated irradiance time series is presented. The fitted timescales for granulation (τ_GR1≈ 237~s and τ_GR2≈ 62~s) are in good agreement with the characteristic lifetimes derived from recent image time series of the Sun's surface (Del Moro 2004); and probably linked to magnetic chromospheric structures such as bright points (Harvey et al. 1993).