2009/11/10 by Douglas Gough, Bradley W. Hindman · 2 citations
Physics and Astronomy · #Adaptive optics and wavefront sensing #Scientific Research and Discoveries #Solar and Space Plasma Dynamics #astro-ph.SR
paper · pdf · doi:10.1088/0004-637x/714/1/960
published as Astrophys.J.714:960-970,2010 · 23 pages, 9 color figures, submitted to the Astrophysical Journal
arxiv created 2009/11/10 · openalex publication_date 2010/04/15 · arxiv updated 2014/11/20 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
Steady meridional flow makes no first-order perturbation to the frequencies of helioseismic normal modes. It does, however, Doppler shift the local wavenumber, thereby distorting the eigenfunctions. For high-degree modes, whose peaks in a power spectrum are blended into continuous ridges, the effect of the distortion is to shift the locations of those ridges. From this blended superposition of modes, one can isolate oppositely directed wave components with the same local horizontal wavenumber and measure a frequency difference which can be safely used to infer the subsurface background flow. But such a procedure fails for the components of the more-deeply-penetrating low-degree modes that are not blended into ridges. Instead, one must analyze the spatial distortions explicitly. With a simple toy model, we illustrate one method by which that might be accomplished by measuring the spatial variation of the oscillation phase. We estimate that by this procedure it might be possible to infer meridional flow deep in the solar convection zone.