[Mesa-users] A Query Regardgin Roche Lobe Overflow and Rate of Binary Mass Transfer

[Evan Bauer]

Hi Pulkit,

It may be useful to review the documentation of the mass transfer scheme options in MESA:
https://docs.mesastar.org/en/release-r22.11.1/reference/binary_controls.html#mdot-scheme <https://docs.mesastar.org/en/release-r22.11.1/reference/binary_controls.html#mdot-scheme>

If you are using the default scheme, the mass transfer rate is described by equation (13) and the surrounding text from this MESA instrument paper based on the Ritter (1988) scheme: https://ui.adsabs.harvard.edu/abs/2015ApJS..220...15P/abstract <https://ui.adsabs.harvard.edu/abs/2015ApJS..220...15P/abstract>

With this scheme, it is possible to have significant mass transfer even when (r - rl)/rl < 0 as long as it is reasonably close to Roche lobe filling.

Cheers,
Evan


> On Nov 17, 2022, at 7:01 AM, Pulkit Ojha via Mesa-users <mesa-users at lists.mesastar.org> wrote:
> 
> Dear Mesa-users, 
> 
> I'm using mesa to evolve LMXB systems with a point mass of 1.35 MSun and a main sequence donor star of mass 1.5 Msun. I have noticed that the rate of mass transfer is significantly high even if the Roche Lobe Overflow factor of the donor star i.e. (r - rl)/rl is of the order of  "- 10^(-4)" or "-10^(-3)".  I agree that it's very slightly negative but certainly not positive which implies that r < rl for the star.
> 
> Is this happening due to software considering the atmosphere over the calculated radius of the donor star or is there some physical aspect I need to consider? It could also be possible because the Roche lobe overflow factor is not a very strict parameter. 
> 
> I would be grateful if someone could help me with some insight over this. 
> 
> Yours Truly
> Pulkit
> 
> -- 
> Pulkit Ojha
> 5th Year Integrated MSc.,
> School of Physical Sciences,
> National Institute of Science Education and Research <https://www.niser.ac.in/>
> Bhubaneswar, INDIA
> 
> 
> 
> _______________________________________________
> mesa-users at lists.mesastar.org
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