Issue |
A&A
Volume 522, November 2010
|
|
---|---|---|
Article Number | L2 | |
Number of page(s) | 4 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361/201015706 | |
Published online | 26 October 2010 |
Letter to the Editor
Turbulent eddy-time-correlation in the solar convective zone
1
Institut d’Astrophysique et de Géophysique, Université de
Liège,
Allée du 6 août 17,
4000
Liège,
Belgium
2
LESIA, UMR8109, Université Pierre et Marie Curie, Université Denis
Diderot, Obs. de Paris, 92195
Meudon Cedex,
France
e-mail: Kevin.belkacem@obspm.fr
3
Institut d’Astrophysique Spatiale, CNRS-Université Paris XI UMR
8617, 91405
Orsay Cedex,
France
4
Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
5
Departamento de Astrofísica, Universidad de La
Laguna, 38206 La
Laguna, Tenerife,
Spain
Received:
7
September
2010
Accepted:
6
October
2010
Theoretical modeling of the driving processes of solar-like oscillations is a powerful way of understanding the properties of the convective zones of solar-type stars. In this framework, the description of the temporal correlation between turbulent eddies is an essential ingredient to model mode amplitudes. However, there is a debate between a Gaussian or Lorentzian description of the eddy-time correlation function (Samadi et al. 2003b, A&A, 403, 303; Chaplin et al. 2005, MNRAS, 360, 859). Indeed, a Gaussian description reproduces the low-frequency shape of the mode amplitude for the Sun, but is unsatisfactory from a theoretical point of view (Houdek 2010, Ap&SS, 328, 237) and leads to other disagreements with observations (Samadi et al. 2007, A&A, 463, 297). These are solved by using a Lorentzian description, but there the low-frequency shape of the solar observations is not correctly reproduced. We reconcile the two descriptions by adopting the sweeping approximation, which consists in assuming that the eddy-time-correlation function is dominated by the advection of eddies, in the inertial range, by energy-bearing eddies. Using a Lorentzian function together with a cut-off frequency derived from the sweeping assumption allows us to reproduce the low-frequency shape of the observations. This result also constitutes a validation of the sweeping assumption for highly turbulent flows as in the solar case.
Key words: convection / turbulence / Sun: oscillations
© ESO, 2010
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