Excitation and damping of p-mode oscillations of alpha Cen B

Details Excitation and damping of p-mode oscillations of alpha Cen B Excitation and damping of p-mode oscillations of alpha Cen B

2008-10-28

arxiv.org/abs/0810.5022v1

Astrophys.J.692:531-537,2009

Astronomy and Astrophysics

Astrophysics

Accepted for publication in ApJ; 19 pages, 6 figures

Scientific paper

10.1088/0004-637X/692/1/531

This paper presents an analysis of observational data on the p-mode spectrum of the star alpha Cen B and a comparison with theoretical computations of the stochastic excitation and damping of the modes. We find that at frequencies > 4500 micro-Hz, the model damping rates appear to be too weak to explain the observed shape of the power spectral density of alpha Cen B. The conclusion rests on the assumption that most of the disagreement is due to problems modelling the damping rates, not the excitation rates, of the modes. This assumption is supported by a parallel analysis of BiSON Sun-as-a-star data, for which it is possible to use analysis of very long timeseries to place tight constraints on the assumption. The BiSON analysis shows that there is a similar high-frequency disagreement between theory and observation in the Sun. We demonstrate that by using suitable comparisons of theory and observation it is possible to make inference on the dependence of the p-mode linewidths on frequency, without directly measuring those linewidths, even though the alpha Cen B dataset is only a few nights long. Use of independent measures from a previous study of the alpha Cen B linewidths in two parts of its spectrum also allows us to calibrate our linewidth estimates for the star. The resulting calibrated linewidth curve looks similar to a frequency-scaled version of its solar cousin, with the scaling factor equal to the ratio of the respective acoustic cut-off frequencies of the two stars. The ratio of the frequencies at which the onset of high-frequency problems is seen in both stars is also given approximately by the same scaling factor.

Affiliated with

Also associated with

No associations

Rating

Excitation and damping of p-mode oscillations of alpha Cen B does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Excitation and damping of p-mode oscillations of alpha Cen B, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Excitation and damping of p-mode oscillations of alpha Cen B will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-485630