Binary stars

From: "Mike Reynolds" <>
Subject: Binary stars
Date: Fri, 14 Nov 97 16:01:53 -0500

     During one of my study hall classes some students starting using the 
     Mars-navigator CD.  They where exploring the Mars Global Surveyor 
     portion, in particular the lesson Beyond the Solar System.  The lab 
     portion of this activity asked the students to try to stabilize the 
     orbits of four planets as they circle the sun.  You can change the 
     mass of each planet, distance from the sun and starting velocity of 
     the planet.  By playing around with these options you are to try to 
     get all four planets in nice elliptical orbits around the sun.  Having 
     done this they then set the mass of one of the planets to 10EE30.  In 
     other words a very large planet.  The gravitational pull of this 
     planet is so strong that it often pulls other planets into orbit 
     around it.  Most of the time it causes the other planets to be either 
     launched, sling shot style, out of the solar system or crash into the 
     sun.  This scenario causes planets to orbit one way and then change 
     directions.  It can cause them to have very bizarre elliptical orbits 
     which seem to be in constant change, but almost always end up 
     launching a planet out of the solar system or into the sun.  After 
     trying unsuccessfully to achieve stable orbits we have come to an 
     interesting conclusion.  
     Many of the star systems in the galaxy are binary star systems, have 
     two stars orbiting each other.  This would be similar to our 
     experiment with the giant planet.  Since we are unable to get planets 
     to achieve stable orbits, is it possible that the same would be true 
     of binary star systems?  We are drawing the conclusion that there 
     would be no Earth sized planets in any of these binary star systems.  
     They would have been either launched into deep space, swallowed by one 
     of the parent stars or more likely never to have formed.  Does anyone 
     have any thoughts on this?  Does anyone have any suggestions as to who 
     might talk to about this?  If you have the Mars Navigator CD, try the 
     lesson yourself.  We have been trying to get stable orbits for 
     sometime and are still unsuccessful.  It doesn't seem to matter where 
     you start the big planet, the results are always the same.  Try it.  
     If nothing else my students got a kick out of watching the blue planet 
     (Earth) get launched into the sun or out into deep space.