[Mesa-users] Regarding some clarifications

Fri May 5 10:39:34 UTC 2023

Dear Natalia,

I am working on a quite similar project and in the beginning of it had the same questions.

For the evaluation of the best model, you should use some figure of merit. As a first order approach, a Chi-Squared (combined) evaluation comparing the values of your model grid to the observed values can be helpful, as a more advanced option a Mahalanobis- distance approach ( as in https://arxiv.org/pdf/1806.06869.pdf) could be advisable. The observational errors itself is a bit more tricky, but in general can also be incorporated in these methods, as demonstrated for the (Asteroseismic) frequency error in the reference provided. If you are interested in discussing this in more detail, just let me know.

Regarding the second question, I hope for advice of more advanced people on this list.

Best

Desmond

> Am 05.05.2023 um 11:45 schrieb Nathali Perera via Mesa-users <mesa-users at lists.mesastar.org>:
> 
> Hello everyone,
> I'm a beginner to MESA and I'm working with this software for my final year research project. I'm currently modeling detached binary star systems which have almost similar masses like 1.875 and 1.856 solar mass. Since the binary star system is detached and not assumed to be mass transferring, these two stars were modeled as single evolutionary stars. Then I tried to change their mass (starting from 1.75 to 1.9 with a step size of 0.05), chemical composition (changes 0.01, 0.014, 0.018), mixing length (change as 1.8 and 0.2), and overshooting (0.005, 0.01,0.015)to see the effect for their evolutionary tracks. My question is, if there is more than one evolutionary track that intersects the star's error box, how do we know the best suitable track for that star? 
> 
> Secondly, I would like to clarify some other questions regarding the code which I used. How can we select when to use 'kap_file_prefix' or 'use_type2_opaities'? Should we use 'kap_file_prefix' for stars that are rich in hydrogen and 'use_type2_opacities' for stars that have heavy metals? If I use both of these two conditions at the same time will MESA select one condition among them?
> 
> And if anyone sees any mistake in my code, please let me know. I would like to learn and correct my mistakes. 
> 
> And I'm using mesa release r22.11.1.I have attached a figure that I obtained from my work and in that figure, I have marked the binary star system with error bars and several evolutionary tracks.
> 
> Thank You
> Nathali Perera
> <inlist.txt><Figure.jpg>_______________________________________________
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