[Mesa-users] Nonphysical behavior of outermost envelope of rapidly rotating stars

Sat Jul 25 03:02:13 EDT 2020

Hi Larry,

it's usually best if you include your inlists as well. Note that although
the fits are good up to Omega_Psi/Omega_cri~0.999, there's still a cap on
the rotational corrections that by default is set lower than this, with the
option
w_div_wcrit_max = 0.9d0
essentially all values that are a function of w are capped to this. This is
just an inherent necessity from the explicit calculation of these
corrections.

Now, given this cap a model can go past Omega_Psi/Omega_cri=1 because the
centrifugal forces are capped in this way. The workaround we have for this
is an implicit method to boost wind strength when approaching critical,
that boosts it just enough so that the star remains at the edge. The test
case high_rot_darkening does this, and you can turn it on with the set of
options

  ! implicit wind scheme when critical rotation is reached
    max_mdot_redo_cnt = 200
    min_years_dt_for_redo_mdot = 1d-5
    surf_w_div_w_crit_limit = 0.99d0
    surf_w_div_w_crit_tol = 0.01d0
    rotational_mdot_boost_fac = 1d10
    rotational_mdot_kh_fac = 1d10
    mdot_revise_factor = 1.1
    implicit_mdot_boost = 0.1

in your controls. This will boost the wind in such a way the star remains
at omega/omega_c<0.99.

And just a last comment, I don't know if you're outputting every step in
your simulations, but your tracks look a bit choppy before the craziness
ensues. This could be a sign of poor timestep resolution.

Cheers

On Fri, Jul 24, 2020 at 10:34 PM Larry Molnar <lmolnar at calvin.edu> wrote:

> I am running the latest MESA based on the revisions described in Paxton et
> al. (2019): MESA R12778, SDK 20.3.2, on a Linux operating system.
>
>
>
> I am interested in rotation of main sequence stars with intermediate mass.
> With the improved estimates of geometrical factors, the ratio OmRat =
> Omega_Psi/Omega_crit should be accurate up to 0.999. However, when we ran
> simple test cases with rotation turned on near ZAMS, we found spurious
> excursions in the H-R diagrams for OmRat_initial >= 0.4. I attach a pair of
> inlist files we used to get to ZAMS and then to turn on rotation from that
> point. We ran cases with initial mass of 1.0 and 2.0 Msun and with a range
> of OmRat_initial up to 0.6. I attach HR diagrams for each mass showing a
> set of curves for different initial OmRat. I also attach plots of
> luminosity vs age and OmRat of the photosphere vs. age for each mass.
>
>
>
> For the initial mass = 2 solar masses case, the excursion in the H-R
> diagram occurs for initial values of OmRat > 0.4. The excursions begin at
> the end of hydrogen burning in the convective core, a time when the OmRat
> should jump up slightly. However, in the misbehaving cases OmRat jumps
> above unity to nonphysical values. The stellar luminosities remain normal
> with time, though. So it seems the only part of the stellar structure that
> is wacky is the outermost envelope. Once the star begins to go up the giant
> branch, everything is normal again.
>
>
>
> For the initial mass = 1 solar masses case, a similar set of excursions
> occurs although the trigger is slightly different. There is no convective
> core to stop burning. The trigger instead is when the OmRat reaches ~0.7.
> As before, everything returns to normal again once the star begins to go up
> the giant branch. I include a table of values below for the case M_init =
> 1.0 and OmRat_init = 0.5. The errant behavior is in profile numbers 7-26.
>
>
>
> Any ideas on what is going on in the code (or if there is something
> different I should do in the control file) are welcome.
>
>
>
> Larry Molnar
>
>
>
> Profile
>
> age
>
> R1
>
> Temp.
>
> Lum.
>
> OmRat
>
> #
>
> y
>
> Rsun
>
> K
>
> Lsun
>
> 0
>
> 3.98E+07
>
> 0.9203
>
> 5239
>
> 5.73E-01
>
> 0.54
>
> 1
>
> 4.47E+07
>
> 0.9339
>
> 5250
>
> 5.95E-01
>
> 0.5476
>
> 2
>
> 8.26E+07
>
> 0.9425
>
> 5252
>
> 6.07E-01
>
> 0.5534
>
> 3
>
> 3.17E+08
>
> 0.9561
>
> 5260
>
> 6.29E-01
>
> 0.5674
>
> 4
>
> 1.55E+09
>
> 0.987
>
> 5268
>
> 6.74E-01
>
> 0.5929
>
> 5
>
> 3.14E+09
>
> 1.0363
>
> 5257
>
> 7.37E-01
>
> 0.6347
>
> 6
>
> 4.60E+09
>
> 1.1119
>
> 5188
>
> 8.05E-01
>
> 0.7127
>
> 7
>
> 5.13E+09
>
> 1.5238
>
> 4457
>
> 8.23E-01
>
> 1.1583
>
> 8
>
> 5.28E+09
>
> 1.5776
>
> 4394
>
> 8.34E-01
>
> 1.2469
>
> 9
>
> 5.84E+09
>
> 1.6156
>
> 4386
>
> 8.68E-01
>
> 1.2807
>
> 10
>
> 6.12E+09
>
> 1.6364
>
> 4381
>
> 8.87E-01
>
> 1.2986
>
> 11
>
> 7.48E+09
>
> 1.7523
>
> 4350
>
> 9.88E-01
>
> 1.3919
>
> 12
>
> 8.72E+09
>
> 1.8746
>
> 4320
>
> 1.10E+00
>
> 1.4736
>
> 13
>
> 9.78E+09
>
> 1.9916
>
> 4293
>
> 1.21E+00
>
> 1.5268
>
> 14
>
> 1.03E+10
>
> 2.0571
>
> 4281
>
> 1.28E+00
>
> 1.5483
>
> 15
>
> 1.07E+10
>
> 2.1132
>
> 4271
>
> 1.34E+00
>
> 1.5672
>
> 16
>
> 1.10E+10
>
> 2.1657
>
> 4261
>
> 1.39E+00
>
> 1.5817
>
> 17
>
> 1.13E+10
>
> 2.2148
>
> 4252
>
> 1.44E+00
>
> 1.5912
>
> 18
>
> 1.15E+10
>
> 2.2598
>
> 4244
>
> 1.49E+00
>
> 1.5959
>
> 19
>
> 1.17E+10
>
> 2.3052
>
> 4236
>
> 1.54E+00
>
> 1.596
>
> 20
>
> 1.19E+10
>
> 2.3419
>
> 4229
>
> 1.58E+00
>
> 1.5928
>
> 21
>
> 1.20E+10
>
> 2.3749
>
> 4223
>
> 1.61E+00
>
> 1.5869
>
> 22
>
> 1.22E+10
>
> 2.4125
>
> 4217
>
> 1.65E+00
>
> 1.5767
>
> 23
>
> 1.27E+10
>
> 2.5281
>
> 4196
>
> 1.78E+00
>
> 1.5202
>
> 24
>
> 1.30E+10
>
> 2.6287
>
> 4181
>
> 1.90E+00
>
> 1.3909
>
> 25
>
> 1.33E+10
>
> 2.6598
>
> 4185
>
> 1.95E+00
>
> 1.1868
>
> 26
>
> 1.34E+10
>
> 2.6092
>
> 4218
>
> 1.94E+00
>
> 0.982
>
> 27
>
> 1.35E+10
>
> 1.8622
>
> 5089
>
> 2.09E+00
>
> 0.5952
>
> 28
>
> 1.35E+10
>
> 1.7896
>
> 5179
>
> 2.07E+00
>
> 0.5577
>
> 29
>
> 1.36E+10
>
> 1.7977
>
> 5175
>
> 2.08E+00
>
> 0.4921
>
> 30
>
> 1.37E+10
>
> 1.8189
>
> 5146
>
> 2.08E+00
>
> 0.4188
>
> 31
>
> 1.38E+10
>
> 1.8553
>
> 5096
>
> 2.09E+00
>
> 0.3655
>
> 32
>
> 1.38E+10
>
> 1.9031
>
> 5045
>
> 2.11E+00
>
> 0.3262
>
> 33
>
> 1.39E+10
>
> 1.9607
>
> 4999
>
> 2.16E+00
>
> 0.297
>
> 34
>
> 1.39E+10
>
> 2.028
>
> 4962
>
> 2.24E+00
>
> 0.275
>
> 35
>
> 1.40E+10
>
> 2.1052
>
> 4933
>
> 2.36E+00
>
> 0.2575
>
> 36
>
> 1.40E+10
>
> 2.1921
>
> 4910
>
> 2.51E+00
>
> 0.2431
>
> 37
>
> 1.40E+10
>
> 2.2873
>
> 4893
>
> 2.70E+00
>
> 0.2315
>
> 38
>
> 1.41E+10
>
> 2.3882
>
> 4881
>
> 2.91E+00
>
> 0.2223
>
> 39
>
> 1.41E+10
>
> 2.4941
>
> 4873
>
> 3.15E+00
>
> 0.2147
>
> 40
>
> 1.42E+10
>
> 2.6087
>
> 4865
>
> 3.42E+00
>
> 0.2078
>
> 41
>
> 1.42E+10
>
> 2.7251
>
> 4858
>
> 3.72E+00
>
> 0.202
>
> 42
>
> 1.42E+10
>
> 2.846
>
> 4851
>
> 4.03E+00
>
> 0.1968
>
> 43
>
> 1.42E+10
>
> 2.9752
>
> 4844
>
> 4.38E+00
>
> 0.192
>
> 44
>
> 1.43E+10
>
> 3.0965
>
> 4839
>
> 4.72E+00
>
> 0.1882
>
> 45
>
> 1.43E+10
>
> 3.2259
>
> 4832
>
> 5.10E+00
>
> 0.1843
>
> 46
>
> 1.43E+10
>
> 3.3599
>
> 4825
>
> 5.50E+00
>
> 0.1807
>
> 47
>
> 1.43E+10
>
> 3.4945
>
> 4817
>
> 5.91E+00
>
> 0.1775
>
> 48
>
> 1.44E+10
>
> 3.6267
>
> 4810
>
> 6.33E+00
>
> 0.1745
>
> 49
>
> 1.44E+10
>
> 3.7604
>
> 4803
>
> 6.76E+00
>
> 0.1717
>
> 50
>
> 1.44E+10
>
> 3.897
>
> 4795
>
> 7.21E+00
>
> 0.1691
>
> 51
>
> 1.44E+10
>
> 4.0306
>
> 4788
>
> 7.67E+00
>
> 0.1666
>
> 52
>
> 1.44E+10
>
> 4.1611
>
> 4780
>
> 8.12E+00
>
> 0.1644
>
> 53
>
> 1.44E+10
>
> 4.2913
>
> 4773
>
> 8.59E+00
>
> 0.1624
>
> 54
>
> 1.44E+10
>
> 4.4265
>
> 4765
>
> 9.08E+00
>
> 0.1603
>
> 55
>
> 1.44E+10
>
> 4.562
>
> 4757
>
> 9.58E+00
>
> 0.1584
>
> 56
>
> 1.44E+10
>
> 4.6921
>
> 4749
>
> 1.01E+01
>
> 0.1567
>
> 57
>
> 1.45E+10
>
> 4.8267
>
> 4742
>
> 1.06E+01
>
> 0.1549
>
> 58
>
> 1.45E+10
>
> 4.9623
>
> 4734
>
> 1.11E+01
>
> 0.1532
>
> 59
>
> 1.45E+10
>
> 5.0033
>
> 4731
>
> 1.13E+01
>
> 0.1528
>
>
>
> Prof. Larry Molnar
>
> Department of Physics and Astronomy
>
> Calvin University
>
> 1734 Knollcrest Circle SE
>
> Grand Rapids, MI 49546-4403 USA
>
>
>
> E-mail: lmolnar at calvin.edu
>
> Phone: 616-526-6341
>
>
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
>
>

-- 
Pablo Marchant Campos
M.Sc on Astrophysics, Universidad Católica de Chile
PhD on Astrophysics, Argelander-Institut für Astronomie, Universität Bonn
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