Has there ever been an observed star collision? If there hasn't, what might occur?
That is not the kind of reference I was looking for.There is http://www.astronomycafe.net/qadir/q179.html" which shows why stars do not collide in normal circumstances. It points out that collisions would be more common in dense regions, like galactic centres, but this is still time scales of millions of years at best for extremely dense regions where we would have little hope of observing anyway.
Well this is completely wrong... Although I don't know the exact probability of a star collision taking place, in an article I read they believed they were happening every 10 seconds. You have to realize how big the universe is, and how little we can observe. The only star collisions visible to man would have to be in our Galaxy, yet there are biliions of Galaxies... Not only that we can't see every star in our own Glalaxy. And the collision have to do more with the proper motion or orbit of the star, stars have elliptical orbits and dependig on their distance to the center of our galaxy, being the center of it's orbit, and their position in their orbit, the stars would more or less run into each other. Gravity plays a role but it is more their orbits that cause the collisions. This obviously is more evident at the galactic center where there is a high density of stars. We allso don't take into affect our time scale as humans, and the actual age of the universe. But you were correct in that they can form novae and supernovae.Collisions between stars are extremely rare. I remember we were asked to make a rough calculation of the frequency of collisions way back in undergraduate astronomy and from memory it was something of the order of 1 collision in a galaxy the size of the Milky Way in the total age of the universe. Correct me if I'm wrong here anyone! In any case it's very rare and I don't know of any observed collisions although the origin of some Gamma Ray Bursts are unknown so it's possible I guess (though probably unlikely, I'm hazy on this area) that the odd collision could cause one of these.
On the other hand, most stars live in multiple star systems where they orbit other stars. The most common is binary stars, two stars orbiting a common centre of mass. This is not because they have passed close to each other at some point but because they form together. Interactions between the two stars are common, since the radius of a star can change significantly during the course of the stars existance. Stars that previously were far enough apart to leave each other alone can then start to exchange mass between them and even merge together.
Binary interactions are thought to be the cause of many types of Novae and Supernovae.
So to sum up, independent stars essential do not happen to run into each other as they wiz around the galaxy but binary stars do interact with their neighbors in interesting ways. We observe this kind of 'collision' if you want to call it that all the time.
OK, I think you're missing the point here.Well this is completely wrong... Although I don't know the exact probability of a star collision taking place, in an article I read they believed they were happening every 10 seconds. You have to realize how big the universe is, and how little we can observe. The only star collisions visible to man would have to be in our Galaxy, yet there are biliions of Galaxies...
You do realize that 10^20 years is orders of magnitude longer than the current age of the Universe, right?FWIW, considering stars not bound to each other, orbiting the galaxy in the Sun's neighborhood, the Sun has about a 71% chance of randomly passing within 1 solar diameter of another star once every 10^20 years.
Yeah, 10 orders of magnitude in fact. Or 10 billion times older than the universe is now. Or 10 billion times longer than an average sun-like star lives.You do realize that 10^20 years is orders of magnitude longer than the current age of the Universe, right?