[mesa-users] wd diffusion

[Robert Farmer]

Hi

You could set in your controls section mass_change = - something so the
star looses mass from its surface. Then hook up your run_star_extras to
stop the run once some amount of H has been removed

Rob

On Mon, Jan 9, 2017 at 12:41 PM, Jing Luan <jingluan.xw at gmail.com> wrote:

> Hi Bill,
>
> Thank you very much :-) One more question please? Since the current wd
> models that I know in mesa already have total hydrogen mass ~ 10^(-4)*M_wd.
> Do you have a model with total H <<10^(-4)*M_wd please? Thank you :-)
>
> Sincerely,
> Jing
>
> On Mon, Jan 9, 2017 at 11:10 AM, Bill Paxton <paxton at kitp.ucsb.edu> wrote:
>
>>
>> On Jan 9, 2017, at 11:03 AM, Jing Luan wrote:
>>
>>  A pure hydrogen atmosphere would be good enough.
>>
>>
>> Good to know.  My advice is forget about diffusion for now and try adding
>> pure H to the surface of an existing model by accretion.
>>
>> something like this with whatever accretion rate you can get away with --
>> try increasing until run into problems.
>>
>>       accrete_same_as_surface = .false.
>>       accrete_given_mass_fractions = .true.
>>       num_accretion_species = 1
>>       accretion_species_id(1) = 'h1'
>>       accretion_species_xa(1) = 1.0
>>       mass_change = 1d-9 ! rate of accretion (Msun/year)
>>
>> The H should stay at the surface unless there is convection reaching it.
>>
>> There are lots of folks on mesa-users who can help with this -- Rob is a
>> hero, but we don't want to overwork him too much!  ;)
>>
>> -b
>>
>>
>>
>>
>> Since I am studying wd's oscillation, the H-He transition would affect a
>> little the eigen frequencies, so it would be better if I have the H-He
>> transition. The hydrogen atm's mass is about 10^(-4) of the wd's mass.
>> M_{wd} = 0.6Msun. Teff ranges from 13000 to 9000, covering the instability
>> strip for DAVs.
>>
>> Many thanks!
>>
>> Sincerely,
>> Jing
>>
>> On Mon, Jan 9, 2017 at 10:35 AM, Bill Paxton <paxton at kitp.ucsb.edu>
>> wrote:
>>
>>> it would also be good to clarify your goals -- are you studying
>>> diffusion, or is diffusion just a way to create models for the topic you
>>> are actually interested in?  if the latter, then there may be other ways to
>>> create models for you with a pure H outer shell that use "stellar
>>> engineering" instead of diffusion.
>>>
>>> b
>>>
>>>
>>> On Jan 9, 2017, at 10:19 AM, Robert Farmer wrote:
>>>
>>> Hi
>>> Have you tried the wd_diffusion and/or the wd_surf_at_tau_1m4
>>> test_suite cases?
>>>
>>> If you have and are still having problems, can you post your inlists
>>> with the changes you've made.
>>>
>>> Regards
>>> Rob
>>>
>>> On Sun, Jan 8, 2017 at 4:55 PM, Jing Luan <jingluan.xw at gmail.com> wrote:
>>>
>>>> Hello,
>>>>
>>>> I'd like to make a WD model with pure hydrogen atmosphere, i.e. all
>>>> heavier elements have settled down. Thus I turn on diffusion in mesa.
>>>> However, mesa has a hard time converging when I also require the surface
>>>> optical depth to be 5 or even lower (actually I need the low optical depth
>>>> part to be treated well in the model). Does anyone know that why diffusion
>>>> does not work well in low optical depth part please? Or how do I get a WD
>>>> model with hydrogen, helium and metals well separated in depth while its
>>>> surface goes up to tau=0.01 please?
>>>>
>>>> Many thanks!
>>>>
>>>> Sincerely,
>>>> Jing
>>>>
>>>> ------------------------------------------------------------
>>>> ------------------
>>>> Check out the vibrant tech community on one of the world's most
>>>> engaging tech sites, SlashDot.org! http://sdm.link/slashdot
>>>> _______________________________________________
>>>> mesa-users mailing list
>>>> mesa-users at lists.sourceforge.net
>>>> https://lists.sourceforge.net/lists/listinfo/mesa-users
>>>>
>>>>
>>> ------------------------------------------------------------
>>> ------------------
>>> Developer Access Program for Intel Xeon Phi Processors
>>> Access to Intel Xeon Phi processor-based developer platforms.
>>> With one year of Intel Parallel Studio XE.
>>> Training and support from Colfax.
>>> Order your platform today. http://sdm.link/xeonphi_______
>>> ________________________________________
>>> mesa-users mailing list
>>> mesa-users at lists.sourceforge.net
>>> https://lists.sourceforge.net/lists/listinfo/mesa-users
>>>
>>>
>>>
>>
>>
>
> ------------------------------------------------------------
> ------------------
> Developer Access Program for Intel Xeon Phi Processors
> Access to Intel Xeon Phi processor-based developer platforms.
> With one year of Intel Parallel Studio XE.
> Training and support from Colfax.
> Order your platform today. http://sdm.link/xeonphi
> _______________________________________________
> mesa-users mailing list
> mesa-users at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/mesa-users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20170109/abded2e4/attachment.html>