Low-degree helioseismology with AIA

Abstract

We form unresolved-sun time series from the 1600 and 1700 Angstrom images produced by the Atmospheric Imaging Assembly, and find a clean low-degree p-mode spectrum at each wavelength. The time series and spectra are compared with Doppler velocity and continuum intensity time series from the Helioseismic and Magnetic Imager and velocity series from the Birmingham Solar Oscillation Network. The UV data have a slight phase shift with respect to the velocity, and show more sensitivity to high-frequency and less to low-frequency modes. Unlike the HMI (visible) continuum observations, the UV spectra show little or no granulation noise at low frequencies and thus potentially allow more low-frequency modes to be recovered. These results suggest that asteroseismology at near-UV wavelengths should be very feasible and even an improvement on visible-wavelength intensity measurements, at least in low-activity stars.