Binary Star Systems

[Matheous-2]

At what sort of distances do the 'average' binary stars systems orbit one another and is the 'gap' dependant on star mass?
This question is just out of sheer curiosity. Thanking ABrs in advance....

[Old_Geezer]

I didn't realise there was an average. Don't they form any distance so long as they are still in adequate gravitational range of each other ?

[jake-the-peg]

No the separation isn't dependant on the star's mass but the separation and their masses determines the period

http://hyperphysics.phy-astr.gsu.edu/hbase/starlog/bistar.html

In practice measuring the separation and period allows you to 'weigh' the pair

[ToraToraTora]

So if our own star was a binary with one of similar mass, how far apart would they be? Could they both have planets? could they swap planet? I mean if the orbits were such that the planet ends up orbiting in non simple track orbit.

[Old_Geezer]

According to JTP it would be related to the period of the orbit.

From what little I've read binary stars can have their own planets. Or objects can orbit both. Woe betide those with a figure of eight route :-)

[jim360]

Binary Star systems are hideously complicated and I don't understand them. For what it's worth, though, there are several different types of binary star system loosely characterised by the relative sizes of the two stars each behaving in a different way. In terms of the possible "figure of eight" orbit, I believe that for most systems there is a single figure-of-eight potential but it's highly unstable and almost certainly in practice no planet would be able to survive in that orbit for long, more than likely decaying to collide with one of the two stars. But most of this is just (hopefully fairly well-informed) speculation, really, and I'd encourage you to read around the subject.

There is a lecture course focusing solely on Binary Star systems that forms part of Cambridge's Part III Maths course. I didn't go.

[Matheous-2]

So, could there be a scenario where one or both stars have planets in orbit and potentially life that might observe TWO suns in their sky simultaneously?

[jake-the-peg]

Here's one

http://scienceblogs.com/SETI/2011/09/15/kepler-16-exoplanets-around-bi/

[jim360]

The short answer is that no-one knows. However this paper:

http://arxiv.org/abs/0705.3444

Provides the current best estimate, that about half of all binary star systems are capable of supporting planets that are capable of supporting life. Whether they do or not...

[ToraToraTora]

George Lucas thought so:
http://www.the-two-malcontents.com/wp-content/uploads/070329_skywalker_02.jpg