[mesa-users] WD models with low temperature
chenhl
chlcrazyboy at gmail.com
Thu Apr 14 16:23:31 EDT 2016
Dear Bill,
Thanks a lot for your reply!
These plots are very helpful for understanding. Now I know what's wrong
with my initial model.
I tried to make a new WD model without the He shell. Then I succeeded to
reduce its central temperature to 1.0e7 K.
Thanks again for your help!
Best wishes,
Hailiang
On Thu, Apr 14, 2016 at 9:02 PM, Bill Paxton <paxton at kitp.ucsb.edu> wrote:
>
> On Apr 14, 2016, at 11:03 AM, chenhl wrote:
>
> Dear Bill,
>
> Thanks a lot for reply!
>
> Actually I have noticed that difference. I have tried to run the
> calculation with which_atm_option = 'grey_and_kap' in the second inlist
> file.
> Indeed the code can keep going. But after one hour, the central
> temperature only change slightly. Then I simply stop the calculation.
>
>
> ok. that's much different behavior that I'm seeing for the C/O wd that is
> used in the wd_cool test case.
>
> let's take a look -- I'm now running with your wd1.mod to see what I find.
>
> some things to try:
>
> varcontrol_target = 5e-5
>
> this is probably much lower than you really need -- at least for initial
> test runs. i'm setting it to 1d-3 for now.
>
> mesh_delta_coeff = 0.7
>
> this is giving us over 2400 cells. we can probably get by with a lot
> fewer. i'm setting it to 1.2 for now.
>
> which_atm_option = 'grey_and_kap'
>
> the surface of your model has X=0, Y=0.92, Z = 0.08 -- so using opacities
> for the surface BC may not be necessary or useful. let's go simpler:
>
> which_atm_option = 'simple_photosphere'
>
>
> now with those changes we see something interesting -- lots of burning is
> still going on!
>
> if you want to get to a cool center for your ONe wd, you have to get
> beyond the stage of doing He burning in the envelope. That means waiting
> patiently while it does flashes, or stepping in and turning on a mass loss
> mechanism of some sort to remove the helium layer at the surface.
>
> There is also still strong C burning happening just below the He layer.
> That will also force smaller timesteps until it finishes.
>
> The cooling of the center will have to wait until the burning completes.
> The model you are starting with is still stuck at the tip of the AGB doing
> He shell flashes and C burning in thin layers near the surface. That
> needs to finish before cooling at the center can get going.
>
> LOOK AT PLOTS TO SEE WHAT IS HAPPENING IN THE MODEL!!!!
> (sorry for the cap's -- sometimes I just can't stop myself from shouting.)
>
>
>
> compare those to the plots for the C/O wd at the start of cooling in
> wd_cool -- the burning is complete in this case and the code can take
> timesteps of millions of years here vs under a year when the burning is
> still going on in your ONe model.
>
>
>
> Cheers,
> Bill
>
>
>
>
>
>
>
>
>
>
>
> In the former email, you said you have a check. I guess you use some CO WD
> models.
> Did you try to use some ONe WD models or the model I attached in the first
> email?
>
> Best wishes,
> Hailiang
>
> On Thu, Apr 14, 2016 at 7:40 PM, Bill Paxton <paxton at kitp.ucsb.edu> wrote:
>
>> Hi,
>>
>> Just as a check, I let wd_cool keep going as long as it could. All was
>> fine until the center temperature dropped below 1e6. At that point we
>> really do fall off the edge of the world in the current eos, and it gives
>> up. So it runs great for about 800 steps, then abruptly dies. Here's the
>> last good model:
>>
>>
>> bill
>>
>>
>>
>>
>>
>>
>>
>> On Apr 14, 2016, at 6:14 AM, chenhl wrote:
>>
>> > Dear all,
>> >
>> > I want to make some ONe WD models with central temperature Tc ~ 1.0e7 K.
>> > But I always fail to cool the WD down.
>> >
>> > I try to do this with two steps.
>> > First, I use make_o_ne_wd test case to make a WD model with a mass I
>> need.
>> > Then I use wd_cool test case to reduce the central temperature. I
>> always fail at the second
>> > step with following error.
>> >
>> >
>> ----------------------------------------------------------------------------
>> > dt
>> 8.7052562366518861D-14
>> > min_timestep_limit
>> 1.0000000000000000D-13
>> >
>> > stopping because of convergence problems dt < min_timestep_limit
>> >
>> >
>> >
>> >
>> > terminated evolution: convergence problems
>> >
>> >
>> > runtime, retries, backups, steps 15.275467
>> 2.000000 188 69 2693
>> > 2693 8.551489 1.065E+05 -12.382713 5.451730 1.253481
>> 0.000000 0.000000 0.000000 0.919403 0.000000 28.486602 3126
>> 188
>> > -19.325921 7.496896 -0.246400 3.879481 5.942448 -99.000000
>> 1.253481 0.000000 0.373003 0.080597 0.014044 6.309162 25
>> 69
>> > 2.3535E+07 24.633374 4.565573 5.439943 7.114711 -6.300953
>> 1.253481 0.030127 0.508866 0.000000 9.860E-01 -0.833E+02
>> convergence
>> >
>> > Fri Apr 15 18:24:37 CST 2016
>> >
>> > ******************************************************************
>> > failed to create cool.mod when running inlist_wd_cool2
>> > ******************************************************************
>> >
>> > The version of MESA I used is 4906. The inlist files I used are
>> attached.
>> >
>> > Is there anyone have experience on this? Thanks!
>> >
>> > Best wishes,
>> > Hailiang
>> >
>> >
>> >
>> >
>> >
>> >
>> <inlist_wd_cool1><wd1.mod><inlist_make_o_ne_wd><inlist_wd_cool2>------------------------------------------------------------------------------
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>>
>>
>
>
>
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