[mesa-users] Bug in edot mechanism in binary module

[Pablo Marchant]

Hi,

thanks for the reminder, this has been fixed in version 9867, and will be
up in the next release.

Let me know if you find anything else!

cheers

On Thu, Jul 6, 2017 at 3:09 AM, Glenn-Michael Oomen <
glennmichael.oomen at kuleuven.be> wrote:

> Hi Mesa,
>
>
> A reminder that this has not yet been fixed.
>
>
> So users that use the binary module and are simulating eccentric orbits
> with the effect of tides included should be careful for this issue.
>
>
> Best regards,
>
> Glenn-Michael Oomen
> ------------------------------
> *Van:* Glenn-Michael Oomen
> *Verzonden:* dinsdag 21 maart 2017 17:56
> *Aan:* mesa-users at lists.sourceforge.net
> *Onderwerp:* Bug in edot mechanism in binary module
>
>
> Dear developers,
>
>
> I would like to report on a bug in the binary_edot file. It concerns the
> tidal mechanism from Hut (1981).
>
>
> In line 129 in the code, there is multiplied by pow_cr(1-b%
> eccentricity**2,6.5d0) instead of divided by it, which has huge
> implications once the eccentricity becomes large (suppose your eccentricity
> is 0.9, this results in a discrepancy of almost 10 orders of magnitude!).
>
>
> So basically in binary_edot.f90, line 128-129:
>
>
> edot_tidal = -27.0d0*qratio*(1+qratio)*pow8(r_phot/osep) &
>             * b% eccentricity*pow_cr(1-b% eccentricity**2,6.5d0)*b% Ftid_1
>
> should be
>
> edot_tidal = -27.0d0*qratio*(1+qratio)*pow8(r_phot/osep) &
>             * b% eccentricity*pow_cr(1-b% eccentricity**2,-6.5d0)*b% Ftid_1
>
>
> as it is given in Eq. 10 of Hut (1981).
>
> Cheers,
> Glenn-Michael Oomen
>
>
>
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>


-- 
Pablo Marchant Campos
M.Sc on Astrophysics, Universidad Católica de Chile
PhD on Astrophysics, Argelander-Institut für Astronomie, Universität Bonn
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