[Mesa-users] Convergence problems for low mass planets

[Josiah Schwab]

Hi Isaac,

Thanks.  This indeed looks like EOS issues.  The default logQ limit is 5.0
in MESA, but you can run into trouble before that.  The timestep falls
because any iteration that evolves for long enough to reach a place where
there's an EOS problem fails.  So there's sort of a "wall".

If you set report_ierr = .true. you can see the details of the failing
calls. You'll find gamma1 is going negative around logRho = 0, logT = 3.5.

If you look in the SCVH paper (
https://ui.adsabs.harvard.edu/abs/1995ApJS...99..713S/abstract) you'll see
this is right around the "notch" in their coverage and the PPT.

I've attached a plot showing gamma1 & your profiles.  Once the model
touches that dark blue area it's dead.  (This also shows you probably
shouldn't feel great about the irradiated model that is just barely running
to completion.)

There's no short-term fix.  We're aware of
https://ui.adsabs.harvard.edu/abs/2019ApJ...872...51C/abstract and are
working towards incorporating it in MESA on the timescale of next
instrument paper.

Josiah

     hydro_call_number, s% dt, dt, dt/secyer, log dt/yr          98
1.1438023329131436D+16    1.1438023329131436D+16    3.6244277104109460D+08
  8.5592394421258557D+00

                                                 csound         410
0.0000000000000000D+00
                                           s% gamma1(k)         410
 -1.9546796997627285D-02
                                               s% cp(k)         410
1.6336434229865569D+08
                                                s% P(k)         410
9.9568253369982886D+11
                                             s% Pgas(k)         410
9.9568253369953088D+11
                                              s% rho(k)         410
7.0483665705460108D-01
                                                s% T(k)         410
3.2968963255952235D+03
                                                 logRho         410
 -1.5191151727684368D-01
                                                   logT         410
3.5181052905068673D+00
                                                   abar         410
1.2479768720681050D+00
                                                   zbar         410
1.0857440384523727D+00
 do_eos_for_cell k         410
 s% lnPgas_flag T
                                                   z =
 1.9999999999999463D-02
                                                   x =
 7.4000000000000055D-01
                                                 Xhe3 =
1.9999183706787520D-05
                                                 Xhe4 =
2.3998000081629320D-01
                                              sum(xa) =
1.0000000000000000D+00
                                                abar =
 1.2479768720681050D+00
                                                zbar =
 1.0857440384523727D+00
                                                Pgas =
 9.9568253369953088D+11
                                             logPgas =
 1.1998120888784946D+01
                                                 rho =
 7.0483665705460108D-01
                                              logRho =
-1.5191151727684368D-01
                                                   T =
 3.2968963255952235D+03
                                                logT =
 3.5181052905068673D+00
                                                logQ =
 4.8118779017094218D+00
                                                logW =
-2.0743002732425229D+00
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20190501/a14773c8/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: gamma1_DT.pdf
Type: application/pdf
Size: 188733 bytes
Desc: not available
URL: <https://lists.mesastar.org/pipermail/mesa-users/attachments/20190501/a14773c8/attachment.pdf>