Impossible to create a stellar collision or a fly by between 2 stars.

[Francyrad]

I was trying to set up a binary system. However, I have agreed that the options for setting the orbit are very limited. For example, it is impossible to impose an eccentricity greater than 1, which makes it impossible to simulate a stellar collision between two desired stars (without necessarily merging).

Would it be nice if:
-Eccentricity greater than 1 could be entered (and more changes in the orbit of the two stars in general)
-The possibility of rotating the star during its relaxation or evolution could be added. The result, during fusion or collision, would be very different if they had their own rotation.
Thank you for your work.

[danieljprice]

+1 vote for the ability to set up eccentricity > 1 in set_binary, this would be nice to have. Note that the full 6-parameter orbital elements (a,e,i,O,w,f) can be specified as optional arguments to set_binary, but I think this only works for bound orbits.

relaxation with rotation is more tricky but I guess just involves relaxing in a rotating frame?

[Francyrad]

relaxation with rotation is more tricky but I guess just involves relaxing in a rotating frame?

Exactly. I did a lot of practice with StarSmasher,

https://github.com/jalombar/starsmasher/

which allows you to choose the rotation of the MESA stars during relaxation. So what you see in SPLASH is a star that is both rotating and relaxing. The results with simulations having the same identical stars, the same identical orbit, but with zero or different rotations, are always different as it changes how the gas is expelled during collisions or smear encounters.

I want to point out that the purpose of this suggestion is the possibility of making smear meetings, even at high speeds, between stars of any type (possibly created with MESA), like in StarSmasher.

I also suggest to insert a script (?) that allows you to determine how much mass has been ejected from each star during the meeting or the fusion. It would be useful to carry out studies of various kinds.

Note that the full 6-parameter orbital elements (a,e,i,O,w,f) can be specified as optional arguments to set_binary, but I think this only works for bound orbits.

It would be fantastic if you could choose few parameters to set an orbit (as a script, without editing the f90 files), for example (incorrect example): eccentricity and semi major axis, eccentricity and periastron separation (very important to get a super precise collision).

Still thank you for your work

Francesco

[Francyrad]

Hello, any news about this update?

Francesco