Eigenfunction Displacements

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KrawalloQualle
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Joined: Mon Feb 11, 2019 6:07 am

Eigenfunction Displacements

Post by KrawalloQualle » Sun May 19, 2019 10:23 am

Hi all,

I was taking a deeper look at the displacements xi_r and xi_h of the eigenfunctions. The documentation states that these are given in units of R_star. But they take values bigger than one. How can this be? Displacements are larger than the stellar radius? Or am I misunderstanding something here?

Greetings
Jess

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rhtownsend
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Posts: 307
Joined: Sun Mar 31, 2013 4:22 pm

Re: Eigenfunction Displacements

Post by rhtownsend » Sun May 19, 2019 5:06 pm

KrawalloQualle wrote:
Sun May 19, 2019 10:23 am
Hi all,

I was taking a deeper look at the displacements xi_r and xi_h of the eigenfunctions. The documentation states that these are given in units of R_star. But they take values bigger than one. How can this be? Displacements are larger than the stellar radius? Or am I misunderstanding something here?

Greetings
Jess
Since GYRE is a linear oscillation code, their normalization is arbitrary. The default normalization convention is that the total mode energy (in units of GM^2/R) is unity, and that may lead to surface values of xi_r and xi_h that exceed R_star. Of course, when using the eigenfunctions to model observations, they can be re-scaled to match the (much smaller) observed surface displacements and/or velocities.

cheers,

Rich

KrawalloQualle
Posts: 5
Joined: Mon Feb 11, 2019 6:07 am

Re: Eigenfunction Displacements

Post by KrawalloQualle » Sun May 26, 2019 4:40 am

Ah, of course. I should have thought about that. Sorry for the dumb question and thank you very much for the fast answer.

Cheers
Jess

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