[mesa-users] Evolving a binary with a WD accretor

[Ruiz, Erick]

Dear Dr. Marchant,

Thank you for taking the time to answer my previous question. That is very useful, but I am still a little confused. Aside from the mass transfer parameters, do I need to tell MESA that the accretor is a WD (so that MESA knows its mass-radius relation)? If we don't specify it to be a WD, won't MESA assume the accretor is a MS star? In that case, the tidal torque on the accretor could be significant, and there may be no room for an accretion disk inside the accretor Roche lobe. Or can I switch off the tidal torque on the accretor?


Best regards,


Erick Ruiz

Texas Tech University


________________________________
From: Pablo Marchant <pamarca at gmail.com>
Sent: Monday, February 15, 2016 9:38 AM
To: Ruiz, Erick
Cc: mesa-users at lists.sourceforge.net
Subject: Re: [mesa-users] Evolving a binary with a WD accretor

Dear Erick, if you are not modelling the WD and just taking it as a point mass, then the nature of that point mass is mainly decided by the mass transfer efficiency. For this I recommend you check the options mass_transfer_alpha, mass_transfer_beta, mass_transfer_gamma and mass_transfer_delta, that allow you to fix fractions of transferred material that are lost from the system in different ways, and transporting varying amounts of angular momentum. To see the detail on how these options (and all other options in MESA/binary) work, please refer to:

http://mesa.sourceforge.net/binary_controls_defaults.html
[http://mesa.sourceforge.net/assets/logo/mesa_logo2_100pt.png]<http://mesa.sourceforge.net/binary_controls_defaults.html>

binary_controls defaults - MESA home<http://mesa.sourceforge.net/binary_controls_defaults.html>
mesa.sourceforge.net
varcontrol_{stage} ¶ Allows binary to set varcontrol_target for each star depending on the stage of evolution. Ignored if < 0. Each one controls the following stages,



To understand what each option means physically, you can refer to, for instance, Tauris & van den Heuvel 2006, section 16.4.1 (http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:astro-ph/0303456). As a starting point, you can use the binary_donor_only_implicit_mdot test_suite case, and add the options I mentioned above in the "&binary_controls" section of the inlist_project file.

On Mon, Feb 15, 2016 at 4:52 AM, Ruiz, Erick <erick.ruiz at ttu.edu<mailto:erick.ruiz at ttu.edu>> wrote:

Hi,


I am currently doing undergraduate research at my university. We are trying to investigate how the metallicity of the stars in a binary system affects the orbital period. However, I am having trouble setting the parameters. For example, I am trying to run a binary evolution for a CV with an initially detached ZAMS donor, evolving the donor star and not evolving the WD (essentially paragraph 7.4 in the 2011 paper, with varying metallicity). Like I said, the problem I am having is that I am not sure how to specify the stellar type (e.g. WD, NS, etc).


I found an answer to a similar question (from 2013) mentioning 'implicit_rlo': https://sourceforge.net/p/mesa/mailman/message/30896796/


However, I was not able to find 'implicit_rlo' or 'inlist_rlo' in the test suite.


Thank you,


Erick Ruiz


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--
Pablo Marchant Campos
M.Sc on Astrophysics, Universidad Católica de Chile
PhD student, Argelander-Institut für Astronomie
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