One planet, two suns, ellipse or hyperbola?

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Discussion Overview

The discussion revolves around the orbital mechanics of a satellite in a dual-star system, specifically addressing the nature of its trajectory in relation to two gravitational sources. Participants explore whether the resulting path would be a conic section and discuss the complexities involved in modeling such systems.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant describes a Java program that calculates orbits around a single gravity source and questions the trajectory of a satellite in a dual-star system, suggesting it could be a conic section.
  • Another participant identifies the problem as the three-body problem, noting the absence of a general formula for such trajectories, except in special cases.
  • A different participant asserts that the trajectories in question are solutions to the two-body problem and emphasizes the lack of a general solution for more than two bodies.
  • One participant introduces the concept of the "restricted three body" problem, which applies when two bodies are in circular orbits with a third body present.
  • A participant suggests an iterative approach to solving the problem by adding the effects of each gravitational source over time, questioning the mathematical validity of this method.
  • Another participant advises that accelerations should be added rather than positions and velocities to determine the satellite's trajectory iteratively.
  • A participant expresses surprise at the stability of such a dual-star system, referencing an external article for context.

Areas of Agreement / Disagreement

Participants generally agree on the complexity of the problem and the limitations of existing models, but there is no consensus on the best approach to simulate the satellite's trajectory or the nature of the resulting paths.

Contextual Notes

The discussion highlights the challenges of modeling gravitational interactions in multi-body systems and the reliance on iterative methods for approximating trajectories. There are unresolved assumptions regarding the stability and behavior of such systems.

Rapidrain
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I've got a nifty java program done which calculates the orbit of a body around a gravity source.

The math and physics are all done for a body around a single gravity source and how to figure whether it's an ellipse, parabola, hyperbola or straight line. But now I've got a new problem.

If I have two gravity sources, like a dual-star system, what kind of geometric path will a satellite form in relation to the two big GSs? Will it be a conic section??

And don't tell me it's impossible! They've already found one! :wink:

http://www.time.com/time/health/article/0,8599,2093423,00.html
 
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This is the three body problem. As far as I know, there is no known formula for such a trajectory. It is only known in special cases.

Here is a nice applet that plots a satellite traveling between two suns: http://alecjacobson.com/programs/three-body-chaos/
 
Hi rapidrain
the answer is: neither. the kind of trajectories you are looking for are the solutions of the two bodies problem.
there is no general solution for more than 2 bodies.
What you must do in your applet is not try to plot your object on known trajectories, but instead simulate what happens step by step by adjusting for each object its position because of its velocity one delta-t before, then calculate the forces, deduce the acceleration, modify the velocity, and do another delta-t etc. etc.

Cheers...
 
What you are looking for is the "restricted three body" problem. That's when you have two bodies in circular orbits, and a third planet.

Here is a java applet

http://mint.sbg.ac.at/rudi/astro/arnsdorf.html
 
Thank you all for your replies.

Imagine taking each of the two gravity sources individually and for an increment of time add the two trajectories. Position and velocity vectors. Then attack the problem anew. I could do this using interations in computer program.

Would that be mathematically acceptable?
 
Add accelerations (which corresponds to adding forces), not positions and velocities. This can be used to determine velocity and position iteratively, and is the usual approach to model those systems.
 
Add the accs, okay.
 
Rapidrain said:
http://www.time.com/time/health/article/0,8599,2093423,00.html

It looks like this: http://tinyurl.com/caejmy3

I'm quite surprised that such a system can be stable.
 

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