Thread: binary star system

Is a star system with more than two stars in a stable orbit possible or would they get out of sync?

These are commonplace. In many of these systems one or more of the component stars are at a great distance from the others, so these can be stable systems.

On checking wikipedia I find that "Multiple-star systems can be divided into two main dynamical classes: hierarchical systems which are stable and consist of nested orbits that don't interact much and so each level of the hierarchy can be treated as a Two-body problem, or the trapezia which have unstable strongly interacting orbits and are modelled as an n-body problem, exhibiting chaotic behavior."

Binary star - Wikipedia, the free encyclopedia

I expect they are as stable as any other orbit.

Originally Posted by RedPanda

Binary star - Wikipedia, the free encyclopedia

I expect they are as stable as any other orbit.

He wasn't asking about binaries, but about systems with more than two stars.

Originally Posted by John Galt

These are commonplace. In many of these systems one or more of the component stars are at a great distance from the others, so these can be stable systems.

On checking wikipedia I find that "Multiple-star systems can be divided into two main dynamical classes: hierarchical systems which are stable and consist of nested orbits that don't interact much and so each level of the hierarchy can be treated as a Two-body problem, or the trapezia which have unstable strongly interacting orbits and are modelled as an n-body problem, exhibiting chaotic behavior."

What might be interesting is whether planets could orbit these star systems in a sufficiently stable way for life to exist. Could be cool to imagine an inhabited world with three suns in the sky - but I suppose with chaotic orbits the planetary motion might be disrupted so much that planets would not exist for long.

This has been studied through computer modelling. Several conceived systems can remain stable over billions of years. Keep in mind that the other stars in the system may be so distant from the planet that they appear as no more than a norma, though bright star. Recall that it has been postulated that the sun is part of a binary system, being accompanied by a small red dwarf, orbiting far out on the fringes of the Oort cloud.

Originally Posted by John Galt

Recall that it has been postulated that the sun is part of a binary system, being accompanied by a small red dwarf, orbiting far out on the fringes of the Oort cloud.

It seems they've done a lot of searching for it, but it doesn't seem to be there.

"As of 2012, over 1800 brown dwarfs have been identified and none of them are inside the Solar System."

"The Infrared Astronomical Satellite (IRAS) failed to discover Nemesis in the 1980s. The 2MASS astronomical survey, which ran from 1997 to 2001, failed to detect an additional star or brown dwarf in the Solar System."

"Using newer and more powerful infrared telescope technology, able to detect brown dwarfs as cool as 150 kelvins out to a distance of 10 light-years from the Sun, results from the Wide-field Infrared Survey Explorer (WISE survey) have not detected Nemesis."

Interesting hypothesis though.

Polaris the North Star is one of these- a triple star system revealed by Hubble.

The closest star system to the sun is usually considered a trinary system. Alpha Centauri A and B are in close orbit about each other, and proxima centauri appears to orbit the pair about 0.24 light years away. However, some astronomers consider proxima centauri to be only temporarily bound to the AB pair, as at .24 light years the gravitational attraction is quite weak.

Originally Posted by RedPanda

Originally Posted by John Galt

Recall that it has been postulated that the sun is part of a binary system, being accompanied by a small red dwarf, orbiting far out on the fringes of the Oort cloud.

It seems they've done a lot of searching for it, but it doesn't seem to be there.

Interesting hypothesis though.

The idea was triggered by an apparent cycle of regular extinctions. The notion was that as the other star 'neared' the sun it destabalised the orbits comets in the Oort cloud. Some of these then plunged into the inner solar system and some of these impacted the Earth. The regularity of the cycles has been disputed and there could be other explanations anyway, but as you say interesting and though now highly unlikely, not entirely impossible.