[mesa-users] Fwd: Constructig ZAEHB or sdB models with different helium core mass by mesa

Bill Paxton paxton at kitp.ucsb.edu
Mon Dec 23 21:59:44 EST 2013


I forgot to Cc this to mesa-users.   It might be of interest, so here it is.


Begin forwarded message:

> From: Bill Paxton <paxton at kitp.ucsb.edu>
> Date: December 23, 2013 6:26:37 PM PST
> To: 军军 郭 <guojunjun532 at 163.com>
> Subject: Re: [mesa-users] Constructig ZAEHB or sdB models with different helium core mass by mesa
> 
> Try this.
> 
> step 1) evolve until create desired mass of he core.  e.g., evolve 4M until has 0.7M he core.
> 	for smaller cores you may want to use smaller starting mass.
> 
>       initial_mass = 4
>       he_core_mass_limit = 0.7
>       when_to_stop_rtol = 1d-3
>       when_to_stop_atol = 1d-5
> 
> step 2) now turn on high wind to remove envelope -- e.g., wind of 10^-6 Msun/year
>       
>       mass_change = -1d-6
>       envelope_mass_limit = 4d-4
>       when_to_stop_rtol = 1d-3
>       when_to_stop_atol = 1d-5
> 
> step 3) finally, turn off the mass loss and adjust composition to get desired helium content, e.g. Y=0.99
> 
>       relax_Y = .true. ! gradually change average Y, reconverging at each step.
>       new_Y = 0.99
> 
> 
> Good luck,
> Bill
> 
> 
> 
> 
> 
> On Dec 23, 2013, at 5:03 PM, 军军 郭 wrote:
> 
>>  Thanks for your suggestion. Actually,I want to construct ZAEHB or sdB models with central helium core mass from 0.3 M_sun to 0.7 M_sun. But those two cases can’t make it true. Are there other ways to achieve it?
>> 
>> 在 2013年12月24日,上午1:45,Bill Paxton <paxton at kitp.ucsb.edu> 写道:
>> 
>>> Hi,
>>> 
>>> There are 2 relevant cases for you to look at in mesa/star/test_suite.
>>> 
>>> 1) create_zahb --- the file zahb_masses.list tells it which masses to create
>>> 
>>> 2) make_sdb -- it starts with a he-core-flash model from a 1.0 Msun, Z=0.02 zams star.
>>> 	then it turns on a strong wind immediately after the flash,
>>> 	terminating when the envelope mass drops to 4d-4 Msun.
>>> 
>>> Try running those, then make variations to get what you want.
>>> 
>>> Cheers,
>>> Bill
>>> 
>>> 
>>> 
>>> 
>>> On Dec 23, 2013, at 1:01 AM, 军军 郭 wrote:
>>> 
>>>> Dear mesa users,
>>>> I want to know how to construct ZAEHB or sdB models with different helium core mass by mesa?
>>>> Thanks!
>>>> Jun-Jun Guo
>>>> 
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>>> 
>> 
> 

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