mesa-users] Problem creating low Z stars and ZAMS models

[Aaron Dotter]

Dear Ale,

If you want a model with a main sequence lifetime of ~12 Gyr for Z=10^-4, I
recommend choosing M ~ 0.8 Msun. For 0.9 Msun, 7-8 Gyr is perfectly
reasonable.

If  you look at the MESA paper, we have an example of 0.8 Msun, Z=10^-4 from
four different codes and they all have MS lifetimes of ~12 Gyr (see figure
19).

Best wishes,
Aaron



On Tue, Nov 2, 2010 at 6:35 PM, Alessandro Patruno <ale.patruno at gmail.com>wrote:

> Hi everyone,
>
> I was playing a bit with the test_suite
> "low_z" and "create_zams" but I found two problems
> I can't solve easily
>
> 1. How do I tell MESA to use a ZAMS model file that I created with
> "create_zams" instead of the default ones ? I just created a Z=0.0001
> ZAMS sequence (for Population II stars) and I'd like to use it now to load
> initial stellar models...
>
>
> 2. I am creating a single star, a main sequence star of 0.9 Msun,
> with Z=0.0001. So I use "low_z" in the test_suite.
> My "inlist_low_z" has the lines:
>
> &star_job
>       mesa_data_dir = '../../../data' ! for eos and opacity tables
>       create_pre_main_sequence_model = .true.
>       save_model_number=635
>       save_model_filename='0p9-z0001.dat'
>
>
> I start with a pre-main sequence model
> and then let the evolution go until the code tells
> me "starting main sequence". This happens at the 635-th time step
> (that's why I wrote save_model_number=635).
> I save the model in the file (0p9-z0001.dat), and I load it in the
> test_suite called "rlo" to do binary evolution.
>
> The inlist_test_rlo file has these lines n the &star_job section:
>
> &star_job
>
>       mesa_data_dir = '../../../data' ! for eos and opacity tables
>       log_columns_file = 'log_columns.list'
>
>       load_saved_model=.true.
>       saved_model_name='../low_z/0p9-z0001.dat'
>
>       pgstar_flag = .true.
>
>
> I place the donor at a very large orbital separation (something like 10^10
> days)
> to "simulate" a single star evolution before doing the real
> binary evolution later.
> However, the evolution is weird, the main sequence lasts for ~7.5 Gyr
> (instead of the expected 12 Gyr)
> and the evolution is very quick with the star becoming fully radiative
> at some point...
>
> Any idea what did I do wrong ??
>
> Many thanks, I really appreciate your support !
>
> Ale
>
>
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