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

Fri Aug 6 07:51:37 UTC 2021

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

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