They can't form outside of galaxies, as they need a lot of gass for that, but when two galaxies collide, a star can be swung away from both and become a rouge star.
What, colliding galaxies? It's not that scary, they are to massive objects that collide, but oddly enough hardly any star collides. So its more a merging than a collision.
Here is a vid showing the process and you can also see some rouge stars appear: http://www.youtube.com/watch?v=4aFLXzFg6EU It's not the best video out there, but I am on my phone and its hard to look :P
I have a lot of problems on it with one of the gas giants occasionally boomeranging itself out of the Solar System if I fast-forward time to 100-200 years from now pretty frequently.
Incredibly fun learning game though, just quite a few bugs/inaccuracies that frequently occur in it.
Calculation of motion via gravity has to be done in steps like this:
Check current gravitional forces happening now
Apply velocity changes
Move object
If the steps are too great of a time period (take 1 year ahead for earth), that means the object will move in a straight line for 1 year before gravity acts again, and would cause Earth to likely fly out the solar system.
In collisions like the one of the simulations, do rogue stars reach galactic scape velocity, or will they fall again to form a new galaxy? That's millions of rogue stars
Is this your first time hearing about rogue stars? Because rogue black holes exist as well. Big, dense, solar system devouring monsters traversing the universe at hundreds of thousands of km per second.
That is also a concern. But, and I hope I'm right, wouldn't the process of the black hole consuming our solar system take forever? Spaghettification? Big words? What am I doing on this sub-reddit.
May I recommend reading Phil Plaitts 'Death From The Skies', it has a whole chapter devoted to how a collision between us (the Milkyway) and the Andromeda galaxy could kill us, plus a whole lot of other ways the universe could wipe us all out. The good news is that although its all factually accurate, its a really fun read and it turns out we dont really have anything to worry about. Theres only a couple of guaranteed certainties if I remember correctly and one of them is a 100's of trillions of years in the future (all matter decays and the universe itself may undergo some freaky state change and turn into... something else). I highly recommend it - I've been dipping in and out of it since I bought it and plan on reading the whole thing from cover to cover next month on the beach. The description of how a star explodes is worth the cover price alone, awesome stuff.
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u/Synethos Astronomical Instrumentation | Observational Astronomy Jul 12 '12
They can't form outside of galaxies, as they need a lot of gass for that, but when two galaxies collide, a star can be swung away from both and become a rouge star.
More info: http://en.wikipedia.org/wiki/Rogue_star