Some general questions.

[SkySteak]

A couple of days ago someone purchased US on Steam for me and I have to say, it's a great program with lots of potential. Despite some bugs and some crashes, it has been an extremely fun simulation program. I do have some general questions though.

1. In some systems I've made, the orbital period tends to constantly vary as it goes around a star (In one example, I had a Sun sized star with a red dwarf closely orbiting it). A planet in orbit around the main star consistently went from about 5.65 to 19 years in a single orbit. Is there any specific reason(s) for what causes this and is there any way to work it what the orbital period really is from such a range of years like that?

2. I do enjoy the idea of binary systems and I noticed Wiki said this orbit was very common: http://upload.wikimedia.org/wikipedia/commons/0/0e/Orbit5.gif In making a binary system, i can only make this sort of orbit if I take a standard binary orbit and then manually move them close together. Only issue is, they have to be very close. Is this just a rule or can I make stars in such an orbit that are far far wider? On top of that planets orbiting such an arrangement would fly off if too close but at the same time, would sometimes get closer from their original orbit. Is there anything specific going on there which is dictating such behavior?

3. Now I want to be able to produce solar systems that produce planets which are in the habitable zone. This goes for things like multi star and single star systems. Basically , how would I go about this in US. I admit I am not very knowledgeable astronomical wise on the conditions needed to create life. What process could I go about that'd let me know what range of orbits/planet sizes, stars etc I could put planets in which would allow them to be habitable?

Thanks for any help. : )

[Ramierez]

1) This is probably due to the planet's data switching which star of the binary is its 'parent'.  If you notice this switch happen when the red dwarf is closer to the planet than the sun-like star, this is probably the answer.

2) You should be able to achieve that orbit, but you might have to play around with the velocities a bit and don't just auto orbit.  Someone more familiar could probably give a detailed explanation on exactly how to do it.

3) Assuming you're referring to using a proto system to generate a star and planets out of dust, currently this is not possible.  As far as having planets/moons/etc in the habital zone of a star, there is an option on the menu for a star to display its habital zone.  When checked, it will create a ring around the star that represents the normal position for the habital zone based on the star's luminosity.  Currently this doesn't take into account multiple star systems and will only give you the habital zone for each star as if it were alone. 

There's probably a mathematical way to combine the luminosities to reach a combined # that would better describe the HZ (like if you can just add, 2 sun-like stars would create a habital zone the same as if you set the luminosity to 2 instead of 1).  This would not be completely accurate, but it would be potentially closer.

[Dan Dixon]

1 - What Ramierez said. Implementing a fix for this is on the community idea list.

2 - Check out this thread to learn about the built-in tools for creating binary orbits:
http://universesandbox.com/forum/index.php/topic,3432.0.html

3 - There's a habitable zone toggle when you select a star, but it only considers a single star and not binary systems. Just yesterday someone also suggested supporting habitable zones for binary star systems.

Post again if you have more questions.

[SkySteak]

1) This is probably due to the planet's data switching which star of the binary is its 'parent'.  If you notice this switch happen when the red dwarf is closer to the planet than the sun-like star, this is probably the answer.

So I should just derive the result of when the parent star has the strongest influence or would the lesser star have an overall effect on the orbiting planet?

2) You should be able to achieve that orbit, but you might have to play around with the velocities a bit and don't just auto orbit.  Someone more familiar could probably give a detailed explanation on exactly how to do it.

That would be useful, thanks. As said apprantely such orbits are common with binaries and I wanted to see if I could get one where the stars are not closely packed together.

Assuming you're referring to using a proto system to generate a star and planets out of dust, currently this is not possible.

No no no no, I was basically asking what you were referencing below which was is there a calculation you can make with stars that would determine the habitable zones in systems like binaries. This would help bypass the single star problem of the habitable zone button. On the subject of that button, would a habitable zone be only around the star and not above or below it? Is this just a design limitation or is there a Scientific reason for that?

2 - Check out this thread to learn about the built-in tools for creating binary orbits:
http://universesandbox.com/forum/index.php/topic,3432.0.html

I saw this before and it was a very useful guide but it does not cover the orbit I was pointing out (unless I missed something), thus my question on it.

3 - There's a habitable zone toggle when you select a star, but it only considers a single star and not binary systems. Just yesterday someone also suggested supporting habitable zones for binary star systems.

I admit that would be awesome.

[Dan Dixon]

I saw this before and it was a very useful guide but it does not cover the orbit I was pointing out (unless I missed something), thus my question on it.

I'm unclear exactly what you're asking. Can you elaborate or point to a binary orbit diagram that you are trying to replicate in Universe Sandbox?

[SkySteak]

http://upload.wikimedia.org/wikipedia/commons/0/0e/Orbit5.gif

This is what I am trying to replicate. Mainly I can do it by doing the standard binary oribt then nudging both stars closer together but I want to know if there is a far more easier way of doing it and if it can be done at a greater distance (it has to be quite close together to work from what I've seen).

[Dan Dixon]

Ahh... So a binary orbit where the orbits are more elliptical instead of circular?

There's nothing built in for that yet. Hmm... Off hand I don't have a good answer to this. I'll think about it.

[SkySteak]

One more quick question, how do you move objects vertically/up and down?

[Ramierez]

One more quick question, how do you move objects vertically/up and down?

The simplest way is through the position variables when you have the object selected.  Just adjust the Z-axis position for up/down.  You can also use this positioning for more specific object placement.

I had a thought regarding the binary orbit...you could try placing a star and then place another but look for the option to the left of the list of objects (should be 3 buttons) the middle one sets it with 0 velocity.  Let the sim run for a few seconds so they start to pick up speed and then use the hand tool on the stars if they are going into a circular orbit.  The hand tool will let you see a white 3D arrow that shows which way the star is accelerating and you can try to play with that to see if you can get them to skim closely by one another from a fair distance.  This *should* get the orbit you want, though there's a good chance it will balance out over time without any outside influence.

[Joshimitsu91]

In making a binary system, i can only make this sort of orbit if I take a standard binary orbit and then manually move them close together. Only issue is, they have to be very close. Is this just a rule or can I make stars in such an orbit that are far far wider?

Its easy(ish) to do

1. Place your two stars while paused, using the option to click and drag velocity (its labelled "Add bodies with no set velocity"). Drag there velocities at about 45 degrees to the line between them.

2. Manually set the total velocity of both stars equal, the further apart they are the less it needs to be, you'll probably have to play around with this (for close stars about 25 km/s each should about do).

3.  Use the "Box Select" tool to select both stars (or just CTRL click) and click "Balance Selected" and optionally "Add Barycenter". This should stop them drifting through space (If it doesn't work straight away, let them do a couple of orbits to stabalise.

And thats it. To change their eccentricity (how oval they are), just change the angle in part 1 or the velocities in part 2. You might have to play around to get used to it. Hope that helped!

Josh



(If you want me to make a video tutorial of this i can do.)

EDIT: I just thought of an easier way to do it!

1. Set up a standard binary orbit, as explained here: http://universesandbox.com/forum/index.php/topic,3432.0.html (see 1st reply).

2. Reduce (or increase) the velocities of both stars.

That should work too