English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

From the seismic data obtained by CoRoT for the star HD 49933 it is possible,as for the Sun, to constrain models of the excitation of acoustic modes byturbulent convection. We compare a stochastic excitation model described inPaper I (arXiv:0910.4027) with the asteroseismology data for HD 49933, a starthat is rather metal poor and significantly hotter than the Sun. Using the modelinewidths measured by CoRoT for HD 49933 and the theoretical mode excitationrates computed in Paper I, we derive the expected surface velocity amplitudesof the acoustic modes detected in HD 49933. Using a calibrated quasi-adiabaticapproximation relating the mode amplitudes in intensity to those in velocity,we derive the expected values of the mode amplitude in intensity. Our amplitudecalculations are within 1-sigma error bars of the mode surface velocityspectrum derived with the HARPS spectrograph. The same is found with the modeamplitudes in intensity derived for HD 49933 from the CoRoT data. On the otherhand, at high frequency, our calculations significantly depart from the CoRoTand HARPS measurements. We show that assuming a solar metal abundance ratherthan the actual metal abundance of the star would result in a largerdiscrepancy with the seismic data. Furthermore, calculations that assume the``new'' solar chemical mixture are in better agreement with the seismic datathan those that assume the ``old'' solar chemical mixture. These resultsvalidate, in the case of a star significantly hotter than the Sun and Alpha CenA, the main assumptions in the model of stochastic excitation. However, thediscrepancies seen at high frequency highlight some deficiencies of themodelling, whose origin remains to be understood.

The CoRoT target HD 49933: 2- Comparison of theoretical mode amplitudes with observations