[mesa-users] Pre-MS to Wolf-Rayet Evolution Problem

[Ian Foley]

Dear Irham,

Just a few thoughts because I've been playing around with progenitors to
core collapse.

1. I'd be allowing much smaller time steps. See the inlist_massive_defaults
in the star directory on how to do this. Sometimes events occur in the
evolution with rapid change and tiny steps are needed to get around them.

2. In my experience, burning the si28 takes a lot of time steps, because
there is such a complex of reactions involved and the internal structure of
the star has H, He,c12,o16-Ne20 and si28 cores. Your choice of reaction net
might be important here, but a large net has a huge impact on performance.
Out of curiosity, what net are you using? If you get your time step down to
about logdt - -5 to -6, it might take 5,000+ steps. Love to know how to
reduce this myself.

3. You have a star with a huge envelope and a lot of H. If you run with
increased mass loss, you might be able to explode away your envelope and
improve performance by simplifying the star internal structure

Kind regards
ian

On 17 October 2016 at 12:46, Irham Taufik <irham.andika at gmail.com> wrote:

> Dear Frank Timmes,
>
> Thank you for your comments and help.
> At that phase the program is automatically terminated and give this
> message
> "stopping because of convergence problems dt < min_timestep_limit". So why
> the evolution of this star can not reach Wolf-Rayet phase? I attached the
> screenshot of my terminal output in this email.
>
> Best regards,
> Irham
>
> On 17 October 2016 at 08:29, Frank Timmes <fxt44 at mac.com> wrote:
>
>> dear irham,
>>
>> please look at your plots and make as strong an effort
>> as you can on your own to understand what is going on.
>> for example, what stage of evolution is the core in?
>> how does this stage of core evolution relate to motion,
>> or lack of motion as the case may be, in an hr diagram?
>>
>> i apologize for not having more time in this discussion board
>> to guide you towards a better grasp of your plots or
>> standard stellar evolution. what i will say is your plots suggest
>> (a) mesa appears to be working just fine and (b) core-collapse is
>> imminent.
>>
>> fxt
>>
>>
>>
>>
>>
>> > On Oct 16, 2016, at 9:02 PM, Irham Taufik <irham.andika at gmail.com>
>> wrote:
>> >
>> > Dear all,
>> >
>> > I attached a figure that shows evolutionary track followed by my star.
>> As I mention before, the track is stuck at the phase that is marked by red
>> circle and can not reach next stage. At that phase the timesteps of
>> computation become small but I don't know why.
>> >
>> > Frank Timmes, can you explain me more about "a very thin surface layer
>> might be causing the small timesteps" ?
>> >
>> >
>> > Best regards,
>> > Irham
>> >
>> > On 17 October 2016 at 01:29, Frank Timmes <fxt44 at mac.com> wrote:
>> > one reason for my question, as matteo noted, is the lack
>> > of a TPAGB phase for massive stars. in addition, the “WR phase”
>> > is usually taken to mean a stripping of the outer hydrogen envelope
>> > that exposes the products of core burning which have been transported
>> > to the outer layers (wn, wc, wo …)
>> >
>> > my current suggestion is to do a more complete analysis of
>> > the evolution - how much mass has been lost, what do the
>> > abundance profiles look like, etc. i suspect, but do not know,
>> > that a very thin surface layer might be causing the small timesteps.
>> >
>> > fxt
>> >
>> >
>> >
>> >
>> >
>> >
>> > > On Oct 16, 2016, at 8:34 AM, Irham Taufik <irham.andika at gmail.com>
>> wrote:
>> > >
>> > > Dear Frank Times,
>> > >
>> > > I attached the evolutionary track of 32 Msun star that is taken from
>> Geneva Stellar Database. Basically, I want to create similar evolutionary
>> track using MESA with same input parameters as in Geneva model.
>> > >
>> > > However, my star stuck in the TPAGB phase (red oval) can not reach
>> desired WR phase (green oval) because the computation is very slow. Is
>> there something wrong with my inlist?
>> > >
>> > > Best regards,
>> > > Irham
>> > >
>> > > On Oct 16, 2016 10:09 PM, "Frank Timmes" <fxt44 at mac.com> wrote:
>> > > hi irham,
>> > >
>> > > it might be useful to know how “WR phase” and “TPAGB” are defined for
>> a 32 msun model.
>> > >
>> > > fxt
>> > >
>> > >
>> > >
>> > >
>> > > > On Oct 16, 2016, at 5:05 AM, Irham Taufik <irham.andika at gmail.com>
>> wrote:
>> > > >
>> > > > Dear all,
>> > > >
>> > > > Currently I use MESA to create evolution model of 32 M_sun star
>> from pre-MS to Wolf-Rayet phase. However, it seems the program only works
>> until TPAGB and cannot reach WR phase. I attached my inlist file in this
>> email. Is there something wrong with my input parameters?
>> > > >
>> > > > Best regards,
>> > > > Irham
>> > > >
>> > > >
>> > > >
>> > > > --
>> > > > Irham Taufik Andika
>> > > > Astronomy Study Program
>> > > > Bandung Institute of Technology, Indonesia
>> > >
>> > > <figure_1.png>
>> >
>> >
>> >
>> >
>> > --
>> > Irham Taufik Andika
>> > Astronomy Study Program
>> > Bandung Institute of Technology, Indonesia
>> > <wr_mod1.png>
>>
>>
>
>
> --
> Irham Taufik Andika
> Astronomy Study Program
> Bandung Institute of Technology, Indonesia
>
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