# Mode lifetimes of stellar oscillations - Implications for asteroseismology - Astrophysics > Solar and Stellar Astrophysics

Mode lifetimes of stellar oscillations - Implications for asteroseismology - Astrophysics > Solar and Stellar Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: Successful inference from asteroseismology relies on at least two things:that the oscillations in the stars have amplitudes large enough to be clearlyobservable; and that the oscillations themselves be stable enough to enableprecise measurements of mode frequencies and other parameters. Solar-like pmodes are damped by convection, and hence the stability of the modes depends onthe lifetime.We seek a simple scaling relation between the mean lifetime of the mostprominent solar-like p modes in stars, and the fundamental stellar parameters.We base our search for a relation on use of stellar equilibrium and pulsationcomputations of a grid of stellar models, and the first asteroseismic resultson lifetimes of main-sequence, sub-giant and red-giant stars.We find that the mean lifetimes of all three classes of solar-like starsscale like $T { m eff}^{-4}$ where $T { m eff}$ is the effectivetemperature. When this relation is combined with the well-known scalingrelation of Kjeldsen and Bedding 1995 for mode amplitudes observed innarrow-band intensity observations, we obtain the unexpected result that theheight the maximum power spectral density of mode peaks in the frequencypower spectrum scales as $g^{-2}$ where $g$ is the surface gravity. As it isthe mode height and not the amplitude that fixes the S-N at which the modescan be measured, and as $g$ changes only slowly along the main sequence, thissuggests that stars cooler than the Sun might be as good targets forasteroseismology as their hotter counterparts. When observations are insteadmade in Doppler velocity, our results imply that mode height then does increasewith increasing effective temperature.

Author: ** W. J. Chaplin, G. Houdek, C. Karoff, Y. Elsworth, R. New**

Source: https://arxiv.org/