Hi Antonio,
if you want to keep a star near a fixed value of omega/omega_crit, you can
make it so at the start of each step the velocity is adjusted to the
desired value. In extras_start_step you can do something like:
omega_crit = star_surface_omega_crit(id,ierr)
if (ierr /= 0) then
write(*,*) "Error in star_surface_omega_crit"
return
end if
call star_set_uniform_omega(s% id, omega_crit*s% job%
new_omega_div_omega_crit, ierr)
if (ierr /= 0) then
write(*,*) "Error in star_set_uniform_omega"
return
end if
which will keep omega to the desired fraction set in
new_omega_div_omega_crit. Output will still differ slightly, as through the
evolution you will get a slight shift by the end of each step.
Cheers
On Fri, Mar 25, 2022 at 5:22 PM AVG via Mesa-users <
mesa-users at lists.mesastar.org> wrote:
> Hi Simon,
>
>
> Thanks for your time. What I want to do is obtaining the pulsation
> frequencies of some stars at some given values of their omega (in different
> moments of each star), so I think I will have to save and restart as you
> say to be able to perform the work.
>
>
> Thank you again for all!
>
>
> Antonio Varo
>
>
>
>
> On 25/3/22 2:27, Simon Murphy wrote:
>
> Hi Antonio,
>
> omega will always change as a function of time because angular momentum is
> conserved and the stellar structure is not constant. The star becomes more
> centrally condensed and the radius increases.
>
> So while your initialisation of rotation will achieve a certain value of
> omega/omega_c *at some point*, it will not stay that way for long.
> Moreover, the star will not remain a uniform rotator, either. If you're
> able to plot the internal rotation rate as a function of (r/R) at a few
> ages, this will become apparent, especially while the star is still
> contracting.
>
> The meaningful question then becomes 'what do you hope to achieve'? That
> is, given the options, do you want to initialise uniform rotation at some
> age and let it evolve as perhaps a star would? Or do you want to force
> uniform rotation throughout the evolution, which might be achieved with a
> further save&restart with a renewed fixed omega/omega_c some time around
> your model 600 (and perhaps 700 too)? Or something else entirely?
>
> - Simon
> ------------------------------
> *From:* AVG <avargar2 at hotmail.com> <avargar2 at hotmail.com>
> *Sent:* 25 March 2022 01:10
> *To:* Simon Murphy <simon.murphy at sydney.edu.au>
> <simon.murphy at sydney.edu.au>; mesa-users at lists.mesastar.org
> <mesa-users at lists.mesastar.org> <mesa-users at lists.mesastar.org>
> *Subject:* Re: [Mesa-users] Setting the value of omega/omega_critical
>
>
> Hello Simon!
>
>
> Firstly, thank you very much for your time.
>
>
> I attach the plots (Figure_5*) of the stellar radius, the nuclear burning
> and the original plot (just to make it easier to compare).
>
>
> I don't know how to take these plots. I see that the radius decreases (and
> so the omega increases). However, this situation doesn't change when I run
> the simulation for 2500 Myears (for example), and I always get a changing
> value of the omega. I also attach the plots of the simulation that ends at
> 2500 Myears (Figure_1*).
>
>
> Best regards,
>
>
> Antonio Varo
>
>
>
> On 23/3/22 22:33, Simon Murphy wrote:
>
> Hi Antonio,
>
> you're setting rotation using the near_zams parameters. I think it's
> important to note that this is not the same as 'after the ZAMS'. I suspect
> the star is still contracting a little, which is why the rotation is still
> increasing after it is initially set.
>
> To confirm (and for the benefit of future readers), please could you plot
> what's happening with (a) the stellar radius, and (b) the nuclear burning,
> alongside your rotation plot?
>
> cheers,
> - Simon
> ------------------------------
> *From:* Mesa-users <mesa-users-bounces at lists.mesastar.org>
> <mesa-users-bounces at lists.mesastar.org> on behalf of AVG via Mesa-users
> <mesa-users at lists.mesastar.org> <mesa-users at lists.mesastar.org>
> *Sent:* 24 March 2022 04:34
> *To:* mesa-users at lists.mesastar.org <mesa-users at lists.mesastar.org>
> <mesa-users at lists.mesastar.org>
> *Subject:* [Mesa-users] Setting the value of omega/omega_critical
>
> Dear all,
>
> I am trying to simulate a rotating star with a given value of its
> omega/omega_critical, but I find that this parameter varies strongly in
> the first 20 Myears of the simulation since the ZAMS starts (I am
> specially interesed on what happens in those first 20 Myears after the
> ZAMS, as the work I am doing is focused on some previous results
> obtained until that time).
>
> In my simulations I turn on the rotation at the begining of ZAMS, and
> shortly after it starts the value of its omega changes quickly, as we
> can see in the image I attach. I want to set the value of the omega
> along the simulation, as I need to analyse results obtained with GYRE
> for some specific omegas (so the increasing behaviour of the omega makes
> it really difficult for me).
>
> I also attach the inlist I have used.
>
> Could someone give me some tips on this? Any help will be appreciated.
>
> Best regards,
>
> Antonio Varo
>
> _______________________________________________
> mesa-users at lists.mesastar.org
> https://lists.mesastar.org/mailman/listinfo/mesa-users
>
>
--
Pablo Marchant Campos
M.Sc on Astrophysics, Universidad Católica de Chile
PhD on Astrophysics, Argelander-Institut für Astronomie, Universität Bonn
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