Welcome, Guest

Author Topic: Questions from a noob  (Read 3413 times)

whitewalker

  • *
  • Posts: 1
Questions from a noob
« on: January 13, 2014, 06:14:25 PM »
I'm trying to put planets/stars as spread out in 3d space as possible, however when I put them too high or low on the Y (vertical) scale they tend to resist.

Sometimes after running the sim for a while I will see stars/planets with velocities near or exceeding the speed of light. Is this a bug? Is it due to the time step accuracy being off?

When I make a black hole (even matching up its size, mass and distance from stars to be the same as the one in our milk way) all stars have a projected path directly for it instead of orbiting. Why is this? How can I fix it ?

Bla

  • Global Moderator
  • *****
  • Posts: 1013
  • The stars died so you can live.
Re: Questions from a noob
« Reply #1 on: January 17, 2014, 12:03:45 PM »
Sometimes after running the sim for a while I will see stars/planets with velocities near or exceeding the speed of light. Is this a bug? Is it due to the time step accuracy being off?
That's a common issue, if the time step is too high, and two objects come close to each other, they (or the smaller one) are likely to reach extremely high velocities. I guess you could call it a bug, at least it's a limitation of numeric Euler integration. It's something that I think will be fixed in the next big release. But the only way to avoid it is to set the timestep down.

When I make a black hole (even matching up its size, mass and distance from stars to be the same as the one in our milk way) all stars have a projected path directly for it instead of orbiting. Why is this? How can I fix it ?
Do you put the stars before or after the black hole? If you put them after, they will probably display projected paths around the black hole.
If you put such a massive black hole near stars with low velocities relative to it and no other massive objects nearby, they will be accelerated nearly directly towards the black hole. Does it still happen if you pause when placing it and reduce its mass to a few suns?
I think there are some features like an auto orbit button you can click to make objects orbit a nearby massive object if you placed the massive black hole after the stars.