[Mesa-users] Using make_o_ne_wd to prepare some white dwarf models
LAM Yi Hua
lamyihua at gmail.com
Mon Jul 23 01:12:50 EDT 2018
Dear mesa community,
It is a kind of self-replied email for the cooling process.
*>If I am not mistaken, to further cool the WD and to make a naked WD, we
need to remove this buffer zone first, otherwise the code cannot proceed
due to unresolved hydro-Newton equation causing termination of dt <
min_timestep_limit=1d-20. I did try to cool the WD (restart the simulation)
after the stage of log_L_lower_limit = 0 and log_cntr_T=8.08 (center
temperature). But it does not work, it keeps stopping with limit of dt <
min_timestep_limit=1d-20, even I tried to change some settings. *
I found and followed some Bill's suggestions in this post:
https://lists.mesastar.org/pipermail/mesa-users/2016-April/006418.html
These few flags should be set as below in order to cool the WD.
varcontrol_target = 1d-3
mesh_delta_coeff = 1.2
and
which_atm_option = 'simple_photosphere'
At the beginning of inlist_wd_cool2, some burnings are still going on.
Starting from around model (cycle) 360, burnings cease to happen, and
central temperature drops to log_center_temp_lower_limit = 7.3d0 as
what I had defined. I found that the HR path of the WD is oscillating
around log L/Ldot= 0 to -3 during the cooling process.
[image: MESA-r10398_wd_cool_001.png]
If I am not mistaken, after the cooling process to
log_center_temp_lower_limit = 7.3, the C-rich buffer zone at the mass
coordinate of 1.195 to 1.175 Mdot still persists.
May I know the proper procedure to remove this buffer zone to make a naked WD?
To do so, do we just simply change the mass fractions of 12C and other
isotopes to 0 in the freshly saved *.mod and *.data files after the
simulation stop? [Question 3]
Do we have to rescale the dq (fraction of total mstar in cell) column?
[Question 4]
And, how about other physical properties recorded in columns of lnd,
lnT, lnR, L, omega, etc. do we need to follow some procedure/method to
change them? [Question 5]
best regards,
Yi Hua
, LAM
-- CaTCh EVEry SiNGle OppORtuNItY WhEN U r StILl alIVe --
---- Success Belonged To Those Who's Willing To Strive For It ----
On Sat, Jul 21, 2018 at 7:44 PM LAM Yi Hua <lamyihua at gmail.com> wrote:
> Dear MESA community,
>
> Recently, I'd like to test some reactions associated with nova outbursts
> using MESA-r10398 and MESA-sdk (revision 245). [Hopefully, older MESA-sdk
> version won't affect the simulation.] So, most probably, the suitable white
> dwarf (WD) model for testing the reactions should be ONe WD, but not CO WD.
>
> I have some questions to ask the community.
>
> FIRST step:
> I used the "make_o_ne_wd" test_suite to prepare some simple white dwarf
> models.
> For the first test, the simulation of this default model stopped at
>
> model 592
> termination code: xa_central_upper_limit
>
> Then, I commented these two lines in the &star_job of inlist_make_o_ne_wd
> file:
>
> ! xa_central_upper_limit_species(1) = 'ne20'
> ! xa_central_upper_limit(1) = 0.35d0
>
> I ran the simulation again, but it stopped at
>
> model 840
> stopping because of problems -- too many retries
> terminated evolution: nonzero_ierr
> termination code: max_number_retries
>
> Perhaps, someone can identify the problem.
>
> Anyway, it is not a big deal. Although the HR diagram shown in Figure 1 of
> make_o_ne_wd/docs/make_o_ne_wd.pdf could not be reproduced, at least I
> can confirm that my installation is successful, and a partial HR diagram
> was produced from log Teff=3.9 up to 5.5 and log L/Ldot = 3.7 up to 4.5.
> Also, I do not think the problem is due to older MESA-SDK version. After
> that, I tested the make_o_ne_wd test_suite of MESA-r8118 with MESA-sdk
> (revision 245). This simulation ran successfully until it terminated with
> log_L_lower_limit. The produced HR diagram make_o_ne_wd (MESA-r8118) is
> not exactly the same as the partial HR diagram of MESA-r10398, in
> particular there is a kink from Teff=3.9 to 4.2 in the HR diagram of
> make_o_ne_wd of MESA-r8118 during the post-AGB stage. In fact, the HR
> diagram shown in Figure 1 of make_o_ne_wd.pdf also has that kink.
>
> As long as we can still produce a WD model eventually, shall we change
> some settings to eliminate/reduce such kink? [Question 1]
>
> Both HR paths produced from MESA-r10398 and MESA-r8118 show some
> oscillation at the end of post-AGB stage, around Teff=5.1 to 5.4 and log
> L/Ldot = 4 to 4.4. If we can still produce a WD model eventually, shall we
> change some settings to eliminate/reduce such oscillation? [Question 2]
>
>
> SECOND step:
> I extend the list of isotopes and reactions stated in co_burn_plus.net which
> is used by make_o_ne_wd. The newly extended list includes 78 isotopes
> (from 1H up to 40Ca) and associated 480 reactions. These 78 isotopes were
> also included by Politano et al. (1995) and Weiss et al. (1990). Also, I
> made a few changes to inlist_make_o_ne_wd:
>
> **************************************************************
> &star_job
> eosDT_use_linear_interp_for_X = .true. < This flag does not exist in
> MESA-r8118. I compare results produced by MESA-r10398 with and without
> this flag.
> < I found that implementing this
> linear interpretation increases mass loss.
> < However, if I switch it to be
> .true. for initiall mass 9.5 Mdot, it causes the problem of dt <
> min_timestep_limit=1d-20 at model 1070.
> < Perhaps, this is not the reason
> causing the problem of dt < min_timestep_limit .
> < There is no problem for
> initial_mass=9.8 or 9.7. Maybe, there are some settings associated with the
> change of initial mass.
>
> ! change_D_omega_flag = .true. < These flags do not exist in MESA-r
> 8118. I switch off these flags because they do not smoothen the post-AGB
> HR path.
> ! new_D_omega_flag = .true. < Bill Paxton said he is
> "experimenting a new scheme to reduce the noise in the rotational mixing
> diffusion coefficients
> < by doing spatial and temporal
> smoothing."
> < The default flags are .false.
>
> &controls
> max_number_retries = 500 < I increased it for
> more attempts solving the hydro-Newton equation before termination.
> max_model_number = 6000 <
>
> ! xa_central_upper_limit_species(1) = 'ne20' < I switched off these
> two flags due to reason mentioned above.
> ! xa_central_upper_limit(1) = 0.35d0 <
>
> min_timestep_limit=1d-20 <
> log_L_lower_limit = 0 <
>
> **************************************************************
>
> I did not apply any "stellar engineering" (trick) during mass loss at
> end-AGB stage when star mass drops from 10 Mdot to 5.5 Mdot.
>
> With defining initial_mass= 10, the simulation stops at log_L_lower_limit
> = 0 and eventually, the star becomes a white dwarf with 16O and 20Ne rich
> core, and log_cntr_T=8.08 (center temperature). The mass fraction of 16O is
> 0.545 from 0 to 1.195 Mdot, whereas the mass fraction of 12C is about 0.427
> at the mass coordinate of 1.195 Mdot and drops to around 0.010 at the mass
> coordinate of 1.175 Mdot. I suppose the small mass region with high
> fraction of 12C is the so-called C-rich buffer zone separating the bottom
> of the convective envelope from the WD surface according to some
> literatures.
>
> If I am not mistaken, to further cool the WD and to make a naked WD, we
> need to remove this buffer zone first, otherwise the code cannot proceed
> due to unresolved hydro-Newton equation causing termination of dt <
> min_timestep_limit=1d-20. I did try to cool the WD (restart the
> simulation) after the stage of log_L_lower_limit = 0 and log_cntr_T=8.08
> (center temperature). But it does not work, it keeps stopping with limit of dt
> < min_timestep_limit=1d-20, even I tried to change some settings.
>
> I think, to proceed the cooling of a WD to the desired temperature, artificially
> removing this buffer zone will be more effective than changing various
> settings of simulation.
> To do so, do we just simply change the mass fractions of 12C and other
> isotopes in the freshly saved *.mod and *.data files to 0 after the
> simulation stop? [Question 3]
> Do we have to rescale the dq (fraction of total mstar in cell) column? [Question
> 4]
> And, how about other physical properties recorded in columns of lnd, lnT,
> lnR, L, omega, etc. do we need to follow some procedure/method to change
> them? [Question 5]
>
> Besides, I did try with initial_mass=9.5d0, but the simulation stops at
> model 1120 due to unresolved hydro-Newton equation and finally it reached
> dt < min_timestep_limit=1d-20. There is no problem to set
> initial_mass=9.8d0. Perhaps, there are some settings directly related to
> the change of initial star mass. May I know the best way to overcome this
> problem? [Question 6]
>
>
> If we would like to use the default EOS and opacity defined in Paxton et
> al MESA-steering paper [Astrophys. J. Suppl. 192 (2011) 3], do we set the
> EOS and opacity as what are defined in the default inlist of make_o_ne_wd
> as below? [Question 7]
>
> eos_file_prefix = 'mesa'
> kappa_file_prefix = 'gs98'
>
> If this is not the correct way, may I know how to define the default EOS
> and opacity? [Question 8]
>
>
> If I am not mistaken, the default reaction library of MESA-r10398 is JINA
> REACLIB, do we still need to include these few lines below in inlist file? [Question
> 9]
> set_rates_preference = .true.
> new_rates_preference = 2
> set_rate_c12ag = 'jina reaclib'
> set_rate_n14pg = 'jina reaclib'
> set_rate_3a = 'jina reaclib'
>
>
> May I know the best option for the below reactions associated with 12C?
> [Question 10]
> Is there anyone would like to share her/his experience?
>
> ! + `'CF88_basic_1212'` : the single rate approximation from CF88.
> ! + `'CF88_multi_1212'` : combines the rates for the n, p, and a
> channels.
> ! c12(c12,n)mg23, c12(c12,p)na23, and c12(c12,a)ne20 and
> ! uses neutron branching from dayras, switkowski, and woosley,
> 1976.
> ! + `'G05'` : based on Gasques, et al. Phys Review C, 72, 025806
> (2005)
>
> set_rate_1212 = ''
>
>
>
> Thanks for your precious time...
> Your responses are very appreciated...
>
>
>
> best regards,
>
> Yi Hua
> LAM
>
> -- CaTCh EVEry SiNGle OppORtuNItY WhEN U r StILl alIVe --
> ---- Success Belonged To Those Who's Willing To Strive For It ----
>
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