[Mesa-users] Case B mass transfer at solar metallicity

[Debasish Dutta]

I forgot to mention in the first email: if I decrease the orbital period, I
get case A mass transfer. The mass transfer starts when the star is still
burning hydrogen in its core. So I had to go to a larger orbital period,
but then I begin to get a mass transfer phase where the luminosity dip is
small.
ᐧ

On Tue, 30 May 2023 at 20:14, Ebraheem Farag <ekfarag at asu.edu> wrote:

> Hello Debasish,
>
> > There is a mass transfer, but what I was worried about is that during
> the mass transfer phase, we should have observed a luminosity dip, but here
> we cannot see any significant luminosity dip during mass transfer.
>
> It's there, just not very large on the scale of your hr diagram, since
> your initial orbital separation is very large. The decrease in luminosity
> during mass-transfer is a result of thermal disequilibrium of the primary
> (donor). On the RGB/AGB the thermal timescale of the primary can be as much
> as ~ 1 order of magnitude lower as compared to the main-sequence. Therefore
> a stronger mass-transfer rate, perhaps due to a lower initial orbital
> separation, is necessary to bring the star farther out of thermal
> equilibrium and induce a large luminosity dip.
>
> Decreasing the initial orbital period 'initial_period_in_days', should
> increase size of the luminosity dip in the hr.
>
> -EbF
>
> On Tue, May 30, 2023 at 7:22 AM Debasish Dutta via Mesa-users <
> mesa-users at lists.mesastar.org> wrote:
>
>> Hi Ebraheem,
>>
>> Thank you very much for your reply. There is a mass transfer, but what I
>> was worried about is that during the mass transfer phase, we should have
>> observed a luminosity dip, but here we cannot see any significant
>> luminosity dip during mass transfer. That was what I meant by a weird HR
>> diagram.
>>
>> Regards
>> Debasish
>> ᐧ
>> ᐧ
>> On Tue, 30 May 2023 at 18:49, Debasish Dutta <debasishdutta1707 at gmail.com>
>> wrote:
>>
>>> Hi Ebraheem,
>>>
>>> Thank you very much for your reply. There is a mass transfer; but what I
>>> was worried about is that during the mass transfer phase, we should have
>>> observed a luminosity dip, but here we cannot see any significant
>>> luminosity dip during mass transfer. That was what I meant by a weird HR
>>> diagram.
>>>
>>> Regards
>>> Debasish
>>> ᐧ
>>>
>>> On Mon, 29 May 2023 at 13:07, Ebraheem Farag <ekfarag at asu.edu> wrote:
>>>
>>>> Hello Debasish,
>>>>
>>>> I'm guessing that by case B mass transfer you mean mass transfer which
>>>> occurs while the donor is in or evolving toward the Red Giant branch.
>>>> In that case I believe this is exactly what you are observing. You have
>>>> a system where M1 (donor) > M2 (BH) when mass transfer begins, as M1
>>>> evolves to the RGB, the envelope expands, fills its Roche-lobe and begins
>>>> stable mass-transfer resulting in an increase in orbital separation until
>>>> the binary completely detaches ( mass-transfer approaches 0). The donor
>>>> star (M1) then continues its normal evolution, with wind driven mass-loss
>>>> stripping the remaining envelope, leaving as a hot exposed helium core at
>>>> helium depletion (a wolf-rayet star).
>>>>
>>>> Hopefully this answers your question.
>>>>
>>>> -EbF
>>>>
>>>> On Sun, May 28, 2023 at 11:18 AM Debasish Dutta via Mesa-users <
>>>> mesa-users at lists.mesastar.org> wrote:
>>>>
>>>>> Hi,
>>>>> I am trying to evolve a binary system with a black hole companion. I
>>>>> am interested in getting a Case B mass transfer. For lower
>>>>> metallicity models (SMC, LMC and Zsun/10), it seems to work well. However,
>>>>> for higher metallicity (~solar) massive models, I could not get the Case B
>>>>> mass transfer. I was using the initial orbital periods as 70 days for the
>>>>> lower metallicity models. In the case of solar metallicity, if I use an
>>>>> extended period (~450 days), I get some weird HR diagrams with the mass
>>>>> transfer phase almost non-existent. I  have attached my inlists and also a
>>>>> HR diagram of a 42 solar mass model at solar metallicity (mass ratio=0.6).
>>>>>
>>>>> I would be glad if someone could help me regarding this.
>>>>>
>>>>> Regards
>>>>> Debasish
>>>>> ᐧ
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