M. Gruberbauer, D. B. Guenther, T. Kallinger
Recent developments in instrumentation (e.g., in particular the Kepler &
CoRoT satellites) provide a new opportunity to improve the models of stellar
pulsations. Surface layers, rotation, and magnetic fields imprint erratic
frequency shifts, trends, and other non-random behaviour in the frequency
spectra. As our observational uncertainties become smaller, these are
increasingly important and difficult to deal with using standard fitting
techniques. To improve the models, new ways to compare their predictions with
observations need to be conceived. In this paper we present a completely
probabilistic (Bayesian) approach to asteroseismic model fitting. It allows for
varying degrees of prior mode identification, corrections for the discrete
nature of the grid, and most importantly implements a treatment of systematic
errors, such as the "surface effects." It removes the need to apply semi-
empirical corrections to the observations prior to fitting them to the models
and results in a consistent set of probabilities with which the model physics
can be probed and compared. As an example, we show a detailed asteroseismic
analysis of the Sun. We find a most probable solar age, including a 35 +- 5
million year pre-main sequence phase, of 4.591 billion years, and initial
element mass fractions of X_0 = 0.72, Y_0 = 0.264, Z_0 = 0.016, consistent with
recent asteroseismic and non-asteroseismic studies.
View original:
http://arxiv.org/abs/1202.2330
No comments:
Post a Comment