[mesa-users] LS

Pablo Marchant pamarca at gmail.com
Tue Aug 16 13:40:22 EDT 2016


Hi Martin. Thanks for reporting this, there is effectively a bug as well as
a typo in the MESA paper. A fix has been commited and will be available in
future versions. Right now, I'd recommend you use the option
use_other_jdot_ls, so you can correct for this issue in your own work
directory, without the need to modify the main MESA source code. This will
help you to later share the input files to reproduce your work.

In case other users are interested to know if this affects them, in order
for this bug to have an effect your binary models must have:
1) Rotating stars.
2) Tidal synchronization
3) Wind mass loss
For users including these three effects, important changes would only be
expected for very close binaries with strong mass loss, with the problem
worsening for mass ratios far from unity.

Please keep digging and reporting issues Martin ;)

On Fri, Aug 12, 2016 at 7:10 PM, Martin C. <martincs14 at gmail.com> wrote:

> Yea it definitely looks wrong to me.
>
> I ran two binary models with the wrong and corrected versions of jdot_ls,
> with
> -primary 40 Msun
> -secondary as point mass, 27 Msun
> -initial period 1.8 days
> -Z = 0.014
> until RLOF.
> The only jdot I have enabled is LS.
> Also I have do_tidal_sync = .true. !default false
>
> Plotting the primary, I got (I hope the figures display in mailing list
> emails)
> [image: Inline image 1]
>
> Recall that in MESA 8118 the J_total history output is wrong, so have to
> correct it manually.
> I don't think J_total should increase here.
> [image: Inline image 2]
>
> [image: Inline image 3]
> [image: Inline image 4]
>
> [image: Inline image 5]
>
>
> And interestingly
> [image: Inline image 6]
> any idea what that's about?
>
>
>
> thanks!
> Martin
>
>
>
>
> On Wed, Aug 10, 2016 at 10:31 PM, Pablo Marchant <pamarca at gmail.com>
> wrote:
>
>> Hi Martin. I think you're right, thanks for reporting this.
>>
>> Let me check some things and I'll get back to you,
>>
>> On Wed, Aug 10, 2016 at 1:58 AM, Martin C. <martincs14 at gmail.com> wrote:
>>
>>> Hi all,
>>>
>>> Forgive me if I'm confused here, but I've convinced myself that equation
>>> 7 in MESA paper 3 has some wrong signs:
>>>
>>> [image: Inline image 1]
>>>
>>> deltaS are changes while S_lost are absolute amounts it seems (positive).
>>> So if the only change in spin AM is due to mass loss, my understanding
>>> is that Jdot_ls should be zero, but with this equation it wouldn't be ?
>>>
>>> The code is faithful to the equation as far as I can tell in
>>> binary_jdot.f90
>>> [image: Inline image 1]
>>> b% s_donor% angular_momentum_removed is a positive quantity when I print
>>> it.
>>>
>>> thanks for any clarification,
>>>
>>> Martin
>>>
>>> --
>>> Martin C.
>>>
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>>
>>
>> --
>> Pablo Marchant Campos
>> M.Sc on Astrophysics, Universidad Católica de Chile
>> PhD student, Argelander-Institut für Astronomie
>>
>
>
>
> --
> Martin C.
>



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