Trinary star systems don't work in US2

[Pup314]

I've been trying to make trinary star systems in US2. The problem is that the third star can't be set up to orbit a barycenter of the first two stars making a binary for the third star to orbit. Gaia knows I've tried doing this several ways. Usually what happens is that the orbit period of days to years is auto locked and cannot be changes. Also the Barycenter of the binary will not allow a third star to orbit its center of mass. I have tried making a third bary center for the third star and the first binary's barycenter. Nope doesn't work I have tried making a barycenter for all three stars. Nope doesn't work. I have tried making a barycenter for all three stars plus the bianry's barycenter. Nope doesn't work. This needs to be addressed. I've been trying to recreate every star system, whether a single star, a binary, or trinary, with and without planets,with asteroid belts and dust disks, All within 20 light years of the Solar system. Making the systems individually and placing them in the workshop. No luck in making Alpha Centauri trinay system, nor that of EZ Aquarii and I think one other trinary.
It would also be nice if we can lock more than one aspect of a star or planet's data. like locking all three mass, dradius, and temperature of a star, then adding in and locking a luminosity. I've had more than one star disappear when trying to set mass, radius, and temperature, when I then changed the luminosity.

[Jar]

We'd like to improve tools for barycenters and setting up multi-body systems in the future, they just aren't currently our highest priority. In the meantime, I'll move this over to the general discussions board in case any one has suggestions for setting up these types of simulations.

Also, have you seen the Alpha Centauri sim that is included in Universe Sandbox?

[OuijaMawl]

The only really easy way I have been able to set up a trinary is to have the third star orbit around the binary pair. It takes some messing around with various orbital elements to make sure the third won't crash into, or be sent flying away, from the pair it's orbiting around.

[Pup314]

Sadly some of the trinaries comprise a close binary pair and a third star that orbits them, and some tiimes it is a single star that is orbited by a binary pair. neither seems to work as a trinary system so far in US2. I have seen the Preset AC trinary in US2, but I was trying to set up custom systems. I'll try modifying the pre-set AC trinary and see if that works, but I am thinking if I mess around with it, it will break the system. I have tried to do an experiment where I added the sun to it as a 4th co-orbiting star and it breaks the system. Like when I try and then add the sun's planets with the "add planets" button it places them around Alpha Centauri A star instead of around the sun. But I will give it a try. So far I have created all the star systems within 20 light years of Earth and they are up in the workshop, if anyone is interested. I have noticed that some of the parameters don't jibe with what wikipedia has on these systems and what US2 has for the stats, specifically surface temps and luminosity for stars.
Thanks for the help though. I will try the pre-set AC trinary and see if I can work with that a bit. Still EZ Aquarii and 2 other star systems can't be fixed with that as a model, i don't believe.
Real universe physics allow for trinaries, US 2 physics does not at this time allow for them. (unless you are a dev. lol)

[Jar]

Originally posted by Pup314:

Real universe physics allow for trinaries, US 2 physics does not at this time allow for them. (unless you are a dev. lol)

Just to be clear, the physics aren't the issue, as the movement of the bodies in these systems follow the same laws of motion as any other body in any other system (as far as the limits of Newtonian physics go, of course!).

When we set up these simulations, we're not changing the physics at all, we're simply able to precisely set position and velocity to make stable orbits. Our longer-term goal is to make the in-game tools and interface in Universe Sandbox just as easy to use and powerful as the back-end code we use to set up simulations. :)

[Pup314]

OK thanks for the clarification.
On a side note I was able to get the trinaries to work (I think) by using the alpha Centauri trinary as a template, and adjusting the stars, and orbital data to make the other three trinary systems for the <20 light year stars to the Solar System. All four being closest to furthest away within 20 light years of Earth: Alpha Centauri trinary, EZ Aquarii trinary, Epsilon Indi trinary, and GJ 1245 trinary. The last one was difficult to get set up.
I ended up using the AC triple as the model, and placed the furthest most star in the place of Proxima Centauri and then the next largest star at the location of A centauri A, and the last star at the location of A Centauri B. resetting each star's parameters and then the closest pair have a barycenter. Once that was done, I clicked all three stars plus the barycenter last and made a second barycenter for all three stars. Cleared and set that second barycenter as the location for the trails and the center for the systems motion, obviously having clicked on it, and then I let it run for a little while. For those stars with planets I added them, and those that had asteroid belts, or cometary or dust rings, I added them as well.
One last thing. Aren't we using Einsteinian gravitational law, not Newtonian now aa Einsteins Space/Time Gravitational Law being the more accurate of the two systems?
I'd love to see, someday, someone use these custom systems and place then in an accurate 3D simulation with their proper distances, vectors, and motions, similar to the closest 100 Star scenario.
All in all, I do hope peopole will use them and enjoy them!

[Pup314]

One more thing, granted I didn't let the sims run very long, so I am hoping they are working as intended. Sadly some of the data for setting upp these systems and stars has yet to be gathered and combed through and reported upon. I am happily expectant that once Webb ST is up and running many of these unknown factors will be observed and published. Many thanks to Wikipedia for their stored knowledge on these and many more star systems. I might go on to include star systems within 30 LY. Oh and if you get the chance sheck out my custom Alpha Centauri trinary based upon US scenario. I removed AC Bb as it has been refuted and doesn't actually exist though Proxima b still does. I added the stellar dust around both AC A and AC B that was discovered back in the early 20th cntury, and set the total mass split between the two stars at 60 and 40 percents respectively.
I think the difficulty lies in the fact that a binary has a common gravitational center but the third star can't use that center or barycenter to orbit around the way US is set up now. It seems to want to orbit one not both of the binary stars, BUT by using the AC triple as a template I might have that beat for now, until it gets updated. Again thanks for your feedback and help!

[OuijaMawl]

Originally posted by Pup314:

One last thing. Aren't we using Einsteinian gravitational law, not Newtonian now aa Einsteins Space/Time Gravitational Law being the more accurate of the two systems?

The sim is N-body so is based in Newtonian principles. The reason for not using relativistic laws is explained in the FAQ topic on the main forum index

[Pup314]

I'll check that out. Thanks again. BTW I hope you check out some of these systems. Some are quiet dynamic, while other are a simple lone star system.