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Mikkel Nørup Lund

Spatial incoherence of solar granulation: a global analysis using BiSON 2B data

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  • Mikkel N. Lund
  • William J. Chaplin, Univ Birmingham, University of Birmingham, Sch Phys & Astron
  • ,
  • Steven J. Hale
  • ,
  • Guy R. Davies, Univ Birmingham, University of Birmingham, Sch Phys & Astron
  • ,
  • Yvonne P. Elsworth, Univ Birmingham, University of Birmingham, Sch Phys & Astron
  • ,
  • Rachel Howe

A poor understanding of the impact of convective turbulence in the outer layers of the Sun and Sun-like stars challenges the advance towards an improved understanding of their internal structure and dynamics. Assessing and calibrating these effects is therefore of great importance. Here, we study the spatial coherence of granulation noise and oscillation modes in the Sun, with the aim of exploiting any incoherence to beat down observed granulation noise, hence improving the detection of low-frequency p modes. Using data from the BiSON 2B instrument, we assess the coherence between different atmospheric heights and between different surface regions. We find that granulation noise from the different atmospheric heights probed is largely incoherent; frequency regions dominated by oscillations are almost fully coherent. We find a randomized phase difference for the granulation noise, and a near zero difference for the evanescent oscillations. Areduction of the incoherent granulation noise is shown by application of the cross-spectrum.

TidsskriftRoyal Astronomical Society. Monthly Notices
Sider (fra-til)3256-3263
Antal sider8
StatusUdgivet - dec. 2017

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