[mesa-users] Problem of fast rotation stars

[Bill Paxton]

Hello Dengkai,

I'm glad you are getting started using MESA.  
I encourage you to join the mesa-users email list and use it for future emails like this one;
there are lots of experienced mesa users who will be able to help you and who know a lot
more than I do about many questions you might have, especially if they are questions
about astrophysics!   

For example, until I got your email I had never tried running
a 1Msun model with fast rotation.   So when I tried I got surprised.
I started with the test_suite/15M_dynamo inlist and made some changes.
Here's the inlist I ended up with.



This seems to run fine with zams surface rotational velocities up to 200 km/sec.


But when I try 300 km/sec things go wildly unstable in a manner I don't understand at all.
While it is still on the main sequence the surface goes crazy.   This is probably a bug in mesa,
but for the moment it is just a mystery.    



So, welcome to MESA!  ;-)    Somethings work and somethings don't.   There's no magic.
If you can find interesting problems for which it works, then you can get some good work done.
For mysteries like this one, we might get lucky and find a solution, but there's no way to know.
It is all an adventure.   You are welcome to join in.

Good luck,
Bill










On Jan 18, 2013, at 7:24 PM, dengkai wrote:

> Dear Bill,
>  
> My name is Dengkai Jiang, and I have a problem about rotation stars.
> 1.       Aim: to study the evolution of very fast rotation stars (~1Msun)
> 2.       Problem: the rotation velocity (sur_v_rot) will “try to” jump to 1028km/s when the star evolves.   
> 3.       MESA version: 4631
> 4.       inlist: attachment (to clear, I use a very simple inlist with rotation)
> 5.       notes:
> (1)    At first, I used the inlist given by Chatzopoulos (2012.748.42). When I found this,  I used a very simple inlist as attached in this email and this problem also happens.
> (2) This jump seems to happen at ω~0.8ωcrit (initial ω~0.5ωcrit)
> (3)    If use a larger initial rotation velocity (new_surface_rotation_v = 400), the star can evolve through. But the rotation velocity (sur_v_rot) is always about 1028km/s.
> (4) If use a larger inital mass star, this jump will happen lately.  
> (5) I tested in another computer with MESA 4028,  and it also happen.
> (6) This problem seems like the problem found by Roberto (ZAMS rotation models problem), which has been solved by your suggestion (set mesh_delta_coeff = 0.5). I have try this setting (0.5) and other sets (0.3, 0.8, 1.5), but the problem is still there.
>  
> I am a new user of MESA, and this problem can be caused by my wrong set which I don't noticed. Please help me and thank you very much.
>  
> In addition, I am very grateful to you for MESA code, which code can make me do some very interest study on the evolution of single and binary stars.
>  
> Best regards,
> Dengkai


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