[Mesa-users] Surface velocity NOT decrease with mass loss

[Rob Farmer]

Hi
So with the brott winds the surface velocities are increasing but the total
angular momentum is decreasing? I suggest you have a look at what the
radius is doing.

Why is the model stopping at carbon burning? If you look at the CO core
mass is ~35Msun which is right on the edge of the pair instability region.
This is a difficult region to model (see the ppisn test case) and your
inlists would need a lot more work to be able to evolve through this region.

You may want to look at
https://ui.adsabs.harvard.edu/abs/2021MNRAS.504..146V/abstract which also
shows what happens when you have massive stars with a wind mass loss less
than what the dutch prescription yields.

Rob

On Fri, 6 Aug 2021 at 09:51, Levi <lileiixx at 163.com> wrote:

> Hi Rob
> Sorry for my negligence， I will provide more detailed data next. If you
> need anything else, please let me know. First is the Kippenhan diagram of
> the model (titled Brott wind), with blue, red and green dotted lines
> representing the helium, carbon and oxygen core, respectively. And you can
> see that the model stops at the formation of the oxygen core.
> > also look at the terminal output to determine what is limiting your
> timesteps?
> I think it's because I set 'surf_w_div_w_crit_limit = 0.98' but the
> surface velocity remained high and could not be reduced as shown on the
> right image above.
> The following two figures show surface velocity and total angular momentum
> over time, respectively, where the abscissa represents the time at which
> the distance model ends.
>
> Then I tried to replace the mass loss scheme with the "Dutch" scheme
> (scaling factor = 0.5). As a result, the model succeeds until the core
> collapse.
>
> So I suspect there may be a problem with the mass loss setup. Two inlists
> are also attached to this email.
>
>
> Thanks for your  time,
> Levi
>
>
> At 2021-08-05 19:48:12, "Rob Farmer" <robert.j.farmer37 at gmail.com> wrote:
>
> Hi
> It's really unclear what is going on, we need more information before
> anyone can help you.
>
> > I looked at the history.data and found that the speed of these models
> was increasing all the time and it seemed that the total angular momentum
> does not decrease with mass loss. The total angular momentum decreases by
> orders of magnitude but I think it's just due to the decline of mass.
>
> The first sentence says that the total angular momentum does not decrease
> with mass loss, but then your next sentence says it decreases by orders of
> magnitude?Which is it? Are you losing angular momentum or not? Plots would
> help here to explain what you think is the problem.
>
> >but when the mass is higher than 44Msun, the model cannot converge when
> the O core is formed.
>
> There are many challenges in modelling massive stars especially regarding
> the envelope. But there's not enough information here. Again plots, like a
> kippenhan, can help, also look at the terminal output to determine what is
> limiting your timesteps? We would also need to see all of your inlists to
> help diagnose a problem.
>
> Rob
>
>
> On Thu, 5 Aug 2021 at 08:51, Levi via Mesa-users <
> mesa-users at lists.mesastar.org> wrote:
>
>> Hi, all
>>
>>
>>
>>  There seems to be something wrong with my mass loss scheme. When the
>> mass is lower than 44Msun, the model can end at the core collapse, but when
>> the mass is higher than 44Msun, the model cannot converge when the O core
>> is formed. I looked at the history.data and found that the speed of these
>> models was increasing all the time and it seemed that the total angular
>> momentum does not decrease with mass loss. The total angular momentum
>> decreases by orders of magnitude but I think it's just due to the decline
>> of mass.
>>
>>
>> After that, I tried to replace the mass loss scheme with the "Dutch"
>> scheme. The model can converge, the speed decreases rapidly, and the total
>> angular momentum decreases by three orders of magnitude.
>>
>>
>> The following are the files that may be required, please see brott_wind
>> subroutine.
>>
>> To add, I set new_surface_rotation_v = 600 and surf_w_div_w_crit_limit =
>> 0.98 .
>>
>>
>> With regards,
>>
>> Levi
>>
>>
>>
>> _______________________________________________
>> mesa-users at lists.mesastar.org
>> https://lists.mesastar.org/mailman/listinfo/mesa-users
>>
>>
>
>
>
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