[Mesa-users] GSF instability

[Jacqueline Den Hartogh]

Hi Nathan,

Yes that's the reason. For stability both criteria should be satisfied and
the second one never is.

Something else: are you familiar with http://adsabs.harvard.edu/abs/
2016MNRAS.457.1711C and http://adsabs.harvard.edu/abs/2010A%26A...519A..16H?
These papers discuss the importance and occurrence of the GSF instability
in stars :)

Cheers,

Jacqueline

On 23 August 2017 at 14:13, Nathan Grin via Mesa-users <
mesa-users at lists.mesastar.org> wrote:

> Dear all,
>
> we were wondering why in star/private/rotation_mix_info.f90, function
> set_D_GSF
> there is no check for the stability against the GSF, other than that the
> GSF velocity exceeds the mu-current.
>
> In principle, there are stability criteria, e.g., heger+ 2000 (eq 41). The
> medium is stable if:
> dj/dr >= 0 and d omega/dz == 0 (in the inviscid limit)
> with j specific angular momentum and z the coordinate along the rotation
> axis
>
> Indeed the second criterion contradicts shellular rotation (except in the
> case of full solid-body), so one may conclude that our rotating models
> should always be unstable against GSF.
>
> is this the reason the criteria are not included?
>
> cheers,
> nathan
>
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