Mode observability

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benfernando
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Joined: Mon Jun 18, 2018 10:10 am

Mode observability

Post by benfernando » Thu Feb 07, 2019 12:57 pm

Hi all,

My apologies for what I'm sure is probably quite a naive question. I'm modelling the oscillation modes of a Main Sequence A-type star and trying to understand which of these modes is likely to be observable. Of course, I restrict this to l = 0,1,2 for geometric cancellation reasons, but am trying to grasp whether the imaginary parts of the eigenfrequencies as calculated by GYRE can be used to deduce Q values, or some such.

As I understand it Im(w) < 0 indicates that the mode is being damped, but does not necessarily mean that the mode is non-observable as energy may be being pumped in through another mechanism faster than the damping occurs (e.g. convective turbulence). Is there a way to use the values or ratio of Im(w) or Re(w) to evaluate mode observability, e.g. through estimations of Q? Or is that not possible in the absence of the generation mechanism physics being included?

Again apologies for this, I suspect the answer is simple but I've not seen the differentiation between observability/non-observabiity discussed much in the modelling literature.

Best,
Ben

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