[Mesa-users] Is it possible to fake a he wd with an envelope?

[Evan Bauer]

Hi Chen,

You might have better luck if you make a He WD that hasn’t cooled as far as the default make_he_wd. For example, you could add the following stopping condition to inlist_wd4:

log_center_temp_lower_limit = 7.3d0

However, it isn’t clear that MESA is really the right tool for what you ultimately want to do here. It sounds like you’re describing dynamically unstable mass loss and envelope ejection, which is an inherently multi-dimensional hydrodynamical process. I would encourage you to read section 2.3 of the third MESA instrument paper https://ui.adsabs.harvard.edu/abs/2015ApJS..220...15P/abstract <https://ui.adsabs.harvard.edu/abs/2015ApJS..220...15P/abstract>
“MESA cannot model common envelope or contact binaries.” 

Cheers,
Evan



> On Mar 6, 2020, at 7:14 PM, Chen DDan <ChenDDan at outlook.com> wrote:
> 
> Hi Evan,
> 
> Thank you so much for your reply. Now i want to simulate the non-conservative mass transfer in a binary consist of a ns and a he wd, i.e.: mass loss from he wd and form a common envelope. Since mesa can only make the two star separately, i want to simulate first the he wd loss mass with mass_transfer_alpha and form an envelope, then to see how it ejects the envelope. I have tried the test_suite make_he_wd. After i make the wd, i add wind to the code and see whether it can produce an envelope that can be ejected. I find from other examples that if some c/o wd with core-envelope couple, the envelope can be ejected by the wind. But the he wd seems do not produce such core-envelope couple. The envelope i means the outer part that have a sharp binding energy decrease at certain boundary, instead of the smooth transition from the core to the envelope. The he wd made from make_he_wd test_suite seems have the smooth core-envelope transition. So i write to see whether i can find any way to produce he wd with a throwable envelope.
> 
> Best Wishes 
> Chen
> 
> 
> 发件人: Evan Bauer <ebauer at physics.ucsb.edu>
> 发送时间: 2020年3月7日 6:40
> 收件人: Chen DDan <ChenDDan at outlook.com>
> 抄送: mesa-users at lists.mesastar.org <mesa-users at lists.mesastar.org>
> 主题: Re: [Mesa-users] Is it possible to fake a he wd with an envelope?
>  
> Hi Chen,
> 
> Could you share some more detail about what you’re trying to accomplish? What exactly do you mean by an “envelope He WD”? It sounds like there are some steps of what you’re describing that should be achievable in MESA (for example you could first use the make_he_wd test_suite and then put an envelope on it by accretion), but we’ll need some more specifics to help you out.
> 
> Cheers,
> Evan
> 
>> On Mar 6, 2020, at 1:01 AM, Chen DDan via Mesa-users <mesa-users at lists.mesastar.org> wrote:
>> 
>> Hi,
>> 
>> Actually, i want to simulate an he wd loss mass to around (with parameter mass_transfer_alpha) and form a common envelope. Since the result make_he_wd test_suite could not make an envelope he wd, and make_co_wd can have an envelope but different inner structure, i want to combine the two to make a he wd with he envelope. Is it possible? If yes, what is the steps?
>> 
>> Best Regards
>> Chen
>> _______________________________________________
>> mesa-users at lists.mesastar.org
>> https://lists.mesastar.org/mailman/listinfo/mesa-users

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