Issue |
A&A
Volume 451, Number 3, June I 2006
|
|
---|---|---|
Page(s) | 1081 - 1089 | |
Section | The Sun | |
DOI | https://doi.org/10.1051/0004-6361:20047133 | |
Published online | 04 May 2006 |
Dynamics of the solar granulation
IX. A global approach
Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, 79104 Freiburg, Germany e-mail: nesis@kis.uni-freiburg.de
Received:
23
January
2004
Accepted:
5
December
2005
Based on a series of spectrograms taken with the German Vacuum Tower Telescope (VTT) at the Observatorio del Teide (Tenerife), we study the temporal evolution of granular dynamics and energy transport in the photospheric layers. We consider the ensemble of the granules cut by the spectrograph slit, modulated by wave motion, as a complex system. We describe this ensemble by the rms of the fluctuations of the observables along the slit: continuum intensity I, gas velocity v measured from line center Doppler shifts with respect to the mean profile, and line width w. The history of the rms of the observables v and w reflects the dynamical change of the system over the 20 min observation time. We find a burst-like change for both observables. However, the cross-correlation between I and v remains virtually constant, with the exception of two gaps. Using six lines of different strength we measure the rms of v in the deep photospheric layers. On the basis of this v variation we derive an upper limit of the kinetic energy flux as a function of height in the photosphere for different times during the observation. The shape of the variation with height is constant over time. A limit for the convective enthalpy flux is calculated using the temperature variations of our earlier models. Its shape remains the same over time. Taken together, these results quantify the different roles that the lower and higher photospheric layers play in the energetics of convective overshoot.
Key words: Sun: photosphere / Sun: granulation
© ESO, 2006
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