Trying to change semi-detached binary hierarchy to contact like.

[mousam100]

Hello developers,
My name is Mousam, and I am very new to Phoebe. I am encountering a problem and would appreciate your suggestions on it. I am attempting to develop a system with parameters such as mass ratio (q), period, temperature of the primary and secondary stars, and semi-major axis (sma) in a semi-detached binary configuration. However, I am finding it challenging to freely adjust these parameters due to constraints inherent in semi-detached binaries. I want to achieve a configuration with a very short period and a small semi-major axis while maintaining the semi-detached nature of the system. Can I achieve this by changing the semi-detached hierarchy to a contact configuration?

When I attempt to change the hierarchy of the semi-detached binary to contact, I encounter errors. Please guide me regarding this. I have provided the code for your reference along with the encountered errors. Thank you for your assistance.

Semi_Detached001.pdf

[kecnry]

It technically is possible (although difficult) to change a bundle from semi-detached to contact, but since you're writing a script anyways, it will be much easier to just modify the call to default_binary. For example the following:

phoebe.default_binary()
phoebe.default_binary(contact=True)
phoebe.default_binary(semidetached='primary')
phoebe.default_binary(semidetached='secondary')

will setup a detached, contact, semidetached where the primary component is at the critical radius, semidetached where the secondary component is at the critical radius, respectively.

If you know that one of your stars is filling its roche lobe, then using the semi-detached constraint makes sense, but generally I'd suggest either using a detached or contact system from the start. A detached system will let a star reach the critical radius (but prevent it from overflowing), whereas a contact system will not allow dropping below the critical value. A "semi-detached" system will enforce one (or both) of the stars to be exactly at the critical radius (completely filling the roche lobe).

Does this help clarify anything at all?

-Kyle

[mousam100]

Thank you Kyle.