[mesa-users] Thermal timescale mass-transfer

Pablo Marchant pamarca at gmail.com
Fri Dec 20 22:28:17 EST 2013


Jaime, here I reproduced Fig 1. (b) of Howell et al. 2001. As I've told you
before. You talk about 5 days, but the works you cited consider initial
orbital periods of less than half a day (unless I'm missing something).

My plot is slightly different at the beginning because magnetic braking is
activated when at least a 75% of the inner 20% of the star in mass is
convective, and using this criteria the very beginning of the evolution has
no magnetic braking (I should probably set these numbers as controls).

I send some inlists to reproduce this, they are meant to be used with the
(unreleased) version 5754.

Cheers!


On Fri, Dec 20, 2013 at 8:05 PM, Jaime Villaseñor <
jaime.villasenor at postgrado.uv.cl> wrote:

> Hi Pablo,  sorry for the poor redaction.
>
> Jaime, I'm not sure what you mean with:
>>
>> "cataclysmic variables evolves in this way as it should with the same
>> test"
>>
>> Are you saying you model a system where you evolve also the full
>> structure of the WD and somehow get a different result? Or you mean that
>> other published results say that and you're trying to reproduce them with
>> MESA? If so, could you provide a reference?
>>
>
> I meant the second. When evolving pre-CVs with the "binary donor only"
> test, I found results that are in agreement with published results, e.g.
> Howell et al. 2001 (ApJ. 550, 897), Knigge et al. 2011 (ApJS, 194, 28).
>
> " I would expect the system to evolve to shorter periods if it is in a
>> synchronous orbit through angular momentum loss"
>>
>> Are you talking about magnetic braking here, which would take angular
>> momentum from the rotation of the star, which would then take angular
>> momentum from the orbit to go into synch? As far as I know, you can get
>> both systems that will get significantly closer to each other, and others
>> for which magnetic braking won't be strong enough, so they will just drift
>> apart. What initial periods are you using?
>>
>
> Yes, I'm talking about magnetic braking taking away angular momentum from
> the orbit of the binary. I'm using a 5 days initial orbital period, so I
> thought that MB should efficiently reduce the orbit of the binary.
>
> In CVs mass transfer is stable, so I want to see now how MESA deals with
> thermal timescale mass-transfer. I've seen the code has convergence
> problems with unstable mass-transfer, but that is another issue.
>
> Best, Jaime.
>
>
>
> 2013/12/20 Pablo Marchant <pamarca at gmail.com>
>
>> Jaime, I'm not sure what you mean with:
>>
>> "cataclysmic variables evolves in this way as it should with the same
>> test"
>>
>> Are you saying you model a system where you evolve also the full
>> structure of the WD and somehow get a different result? Or you mean that
>> other published results say that and you're trying to reproduce them with
>> MESA? If so, could you provide a reference?
>>
>> I also don't get what you say with:
>>
>> " I would expect the system to evolve to shorter periods if it is in a
>> synchronous orbit through angular momentum loss"
>>
>> Are you talking about magnetic braking here, which would take angular
>> momentum from the rotation of the star, which would then take angular
>> momentum from the orbit to go into synch? As far as I know, you can get
>> both systems that will get significantly closer to each other, and others
>> for which magnetic braking won't be strong enough, so they will just drift
>> apart. What initial periods are you using?
>>
>>
>> On Thu, Dec 19, 2013 at 9:46 PM, Jaime Villaseñor <
>> jaime.villasenor at postgrado.uv.cl> wrote:
>>
>>> Dear mesa users,
>>>
>>> I've been trying to reproduce the evolution of a binary system that
>>> should enter into a thermal timescale mass-transfer phase with the "binary
>>> donor only" test. I found that at some point after mass transfer starts
>>> (around 5 Gyr), the orbital period is dramatically increased from the
>>> initial 5 days to around 30 days. However, I would expect the system to
>>> evolve to shorter periods if it is in a synchronous orbit through
>>> angular momentum loss. I'm assuming this because cataclysmic variables
>>> evolves in this way as it should with the same test.
>>>
>>> Any idea on what am I missing here?
>>> I'm using mesa version 5595 and evolving a WD  of 0.8 solar masses and a
>>> donor of 1.3 Msun.
>>>
>>> Thanks as usually for your valuable help.
>>> Best, Jaime.
>>>
>>>
>>> --
>>> Jaime Villaseñor
>>> Master's student in Astrophysics
>>> Universidad de Valparaíso
>>>
>>>
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>>
>>
>> --
>> Pablo Marchant Campos
>> M.Sc on Astrophysics, Universidad Católica de Chile
>> PhD student, Argelander-Institut für Astronomie
>>
>
>
>
> --
> Jaime Villaseñor
> Master's student in Astrophysics
> Universidad de Valparaíso
>



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