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Gaussian Process Modelling of Asteroseismic Data | | Brendon J. Brewer
; Dennis Stello
; | | Date: |
23 Feb 2009 | | Abstract: | The measured properties of stellar oscillations can provide powerful
constraints on the internal structure and composition of stars. To begin this
process, oscillation frequencies must be extracted from the observational data,
typically time series of the star’s brightness or radial velocity. In this
paper, a probabilistic model is introduced for inferring the frequencies and
amplitudes of stellar oscillation modes from data, assuming that there is some
periodic character to the oscillations, but that they may not be exactly
sinusoidal. Effectively we fit damped oscillations to the time series, and
hence the mode lifetime is also recovered. While this approach is
computationally demanding for large time series (> 1500 points), it should at
least allow improved analysis of observations of solar-like oscillations in
subgiant and red giant stars, as well as sparse observations of semiregular
stars, where the number of points in the time series is often low. The method
is demonstrated on simulated data and then applied to radial velocity
measurements of the red giant star xi Hydrae, yielding a mode lifetime between
0.41 and 2.65 days with 95% posterior probability. The large frequency
separation between modes is ambiguous, however we argue that the most plausible
value is 6.3 microHz, based on the radial velocity data and the star’s position
in the HR diagram. | | Source: | arXiv, 0902.3907 | | Services: | Forum | Review | PDF | Favorites | |
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