[mesa-users] bad angular_momentum_j

[Pablo Marchant]

Ok, but checking the output wont help here since no output will be made for
the problem step. So I'd recommend you put some write statements to see
what is changing (something is changing!). Figure out the source of the
jump in jdot, an you'll get your answer.

This goes beyond the physical question of whether such a star would undergo
any braking at all.

On Mon, Aug 15, 2016 at 10:22 PM, Kenny Van <kvan at ualberta.ca> wrote:

> Hi Pablo,
>
> Sorry for the late reply. I would be under the impression that I'm always
> capturing the same convective zone. I haven't had a chance to make a super
> thorough check but looking at the kippenhahn diagrams produced by this test
> the conv_mx1 and conv_mx2 check should pull the outer convective envelope.
> Once the star has dropped to 0.26 msun it shouldn't have much of a outer
> convective envelope.
>
> The check I made there was due to a numerical issue I ran into before
> where some of the outputs would be -1e-99. I just needed to get rid of
> those.
>
> On 12 August 2016 at 22:49, Pablo Marchant <pamarca at gmail.com> wrote:
>
>> You are trying to get the turnover time for an outer convection zone,
>> right? I see you take the sum of dr/conv_vel for radii above
>>
>> envelope_edge = max(s% conv_mx1_bot_r, s% conv_mx2_bot_r)
>>
>> you should be careful as small convective regions can turn on and off,
>> and that can cause a sudden change on your turnover time. Do you know if
>> you are capturing the same convective zone all the time? What is the mass
>> coordinate corresponding to that? In particular, you have a system where,
>> if I have it right, a 1 msun star at TAMS is stripped by a mysterious
>> object (I'll guess a NS as you chose a mass of 1.4 msun) and goes down to
>> 0.26 msun. Does this star even have a relevant outer convective zone left
>> at this point?
>>
>> Check the structure of your star to see if what you are doing makes
>> sense, doing some Kippenhahn plots should be useful. In this note, it is
>> very useful if you actually summarize what is your initial setup, what your
>> model is doing, what you believe it should be doing, and at which point its
>> crashing,
>>
>> Also quick comment
>>
>> #########################################################
>>          if (turnover_time .lt. 0.0) then
>>              turnover_Time = 2.8d6
>>             ! If the turnover time is less than zero, set it so that the
>>             ! MB tt boost is 1
>>          end if
>> #########################################################
>>
>> Why do you create a check to silently ignore something that should not
>> happen?
>>
>> On Sat, Aug 13, 2016 at 3:32 AM, Kenny Van <kvan at ualberta.ca> wrote:
>>
>>> Hi Josiah,
>>>
>>> Yes. there are sometimes oscillations in the results. I was trying to
>>> take the sum of all of the dr/conv_vel as the integral of dr/conv_vel in my
>>> code.
>>>
>>> On 12 August 2016 at 19:30, Josiah Schwab <jwschwab at berkeley.edu> wrote:
>>>
>>>> Hi Kenny,
>>>>
>>>> Isn't this the only way to calculate the convective turnover time
>>>>> though? It's normally calculated as
>>>>>
>>>>
>>>>>
>>>> integral from surface of star to bottom of convective envelope dr /
>>>>> convective velocity.
>>>>>
>>>>> I'm not sure how else to calculate this value except by taking
>>>>> dr/conv_vel in MESA
>>>>>
>>>>
>>>> Bill's point is that dr/conv_vel itself isn't a physical quantity,
>>>> because that's just a statement about the resolution.  The integral of
>>>> dr/conv_vel is a physical quantity, and should be resolution-independent in
>>>> a converged simulation.  Is the integral having large model-to-model jumps?
>>>>
>>>> Josiah
>>>>
>>>>
>>>
>>>
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>>
>>
>> --
>> Pablo Marchant Campos
>> M.Sc on Astrophysics, Universidad Católica de Chile
>> PhD student, Argelander-Institut für Astronomie
>>
>
>


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