Numerical 3D constraints on convective eddy time-correlations: Consequences for stochastic excitation of solar p modes
Abstract
A 3D simulation of the upper part of the solar convective zone is used to obtain information on the frequency component, chik , of the correlation product of the turbulent velocity field. This component plays an important role in the stochastic excitation of acoustic oscillations. A time analysis of the solar simulation shows that a Gaussian function does not correctly reproduce the nu -dependency of chik inferred from the 3D simuation in the frequency range where the acoustic energy injected into the solar p modes is important (nu =~ 2 - 4 mHz). The nu -dependency of chik is fitted with different analytical functions which can then conveniently be used to compute the acoustic energy supply rate P injected into the solar radial oscillations. With constraints from a 3D simulation, adjustment of free parameters to solar data is no longer necessary and is not performed here. The result is compared with solar seismic data. Computed values of P obtained with the analytical function which fits best chik are found ~ 2.7 times larger than those obtained with the Gaussian model and reproduce better the solar seismic observations. This non-Gaussian description also leads to a Reynolds stress contribution of the same order as the one arising from the advection of the turbulent fluctuations of entropy by the turbulent motions. Some discrepancy between observed and computed P values still exist at high frequency and possible causes for this discrepancy are discussed.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 2003
- DOI:
- 10.1051/0004-6361:20030504
- arXiv:
- arXiv:astro-ph/0304457
- Bibcode:
- 2003A&A...404.1129S
- Keywords:
-
- convection;
- turbulence;
- stars: oscillations;
- Sun: oscillations;
- Astrophysics
- E-Print:
- 11 pages