by Ann » Sun Sep 30, 2012 8:58 am
FLPhotoCatcher wrote:
I've sometimes wondered about the gas molecules or atoms and why they collide so much - are they really so much closer to each other compared to their size than stars? Is there an electro-magnetic force that extends past the electrons that causes more collisions than might be expected?
Stars are, basically, "massive point sources" (well, from a "cosmic size" point of view), and they are also very far from one another, typically separated by a few light-years. Gas clouds are extremely spread out and extremely tenuous. But they are also so close that they are "touching" one another in a galaxy. There is no such thing as a perfect vacuum anywhere in a galaxy, meaning that all the seemingly "empty spaces" are filled with a thin, thin gas. Individual gas clouds may move in different directions and collide with each other. When gas in one cloud slams into the gas in another cloud in a collision that may happen over tens, hundreds, thousands or ten thousands of light years, many of the constituent hydrogen atoms are bound to collide with many of the constituent atoms in the other cloud. And even if the atoms don't collide "head on" in such a way that a proton smashes into another proton (which is incredibly unlikely, given the fact that protons repel each other strongly), the atoms may still "collide" so that their electrons are sent into a higher orbit by the extra energy they are imparted by the energy of the collision (whatever the word "collision"
exactly implies). When the electrons then fall back into their original state, they will radiate a photon of energy.
Take a look at this image of the
Vela Supernova Remnant. When the Vela supernova exploded, perhaps 10,000 years ago or so (I'm too lazy to google it, sorry), a few solar masses of gas was flung rather violently away from the exploding star. The "collision fronts" are still glowing, as the gas slams into the thin ambient gas known as the interstellar medium. In the picture, you can see what looks like a complex network of bubble shapes. The "bubbles" glow at the edges, where the actual collision is taking place. The Vela Supernova Remnant is still expanding.
Ann
[quote]FLPhotoCatcher wrote:
I've sometimes wondered about the gas molecules or atoms and why they collide so much - are they really so much closer to each other compared to their size than stars? Is there an electro-magnetic force that extends past the electrons that causes more collisions than might be expected?[/quote]
Stars are, basically, "massive point sources" (well, from a "cosmic size" point of view), and they are also very far from one another, typically separated by a few light-years. Gas clouds are extremely spread out and extremely tenuous. But they are also so close that they are "touching" one another in a galaxy. There is no such thing as a perfect vacuum anywhere in a galaxy, meaning that all the seemingly "empty spaces" are filled with a thin, thin gas. Individual gas clouds may move in different directions and collide with each other. When gas in one cloud slams into the gas in another cloud in a collision that may happen over tens, hundreds, thousands or ten thousands of light years, many of the constituent hydrogen atoms are bound to collide with many of the constituent atoms in the other cloud. And even if the atoms don't collide "head on" in such a way that a proton smashes into another proton (which is incredibly unlikely, given the fact that protons repel each other strongly), the atoms may still "collide" so that their electrons are sent into a higher orbit by the extra energy they are imparted by the energy of the collision (whatever the word "collision" [i]exactly[/i] implies). When the electrons then fall back into their original state, they will radiate a photon of energy.
Take a look at this image of the [url=http://ic2.pbase.com/o6/82/431282/1/110170919.RjJx1MMI.VelaSupernovaRemnantwidefield.jpg]Vela Supernova Remnant[/url]. When the Vela supernova exploded, perhaps 10,000 years ago or so (I'm too lazy to google it, sorry), a few solar masses of gas was flung rather violently away from the exploding star. The "collision fronts" are still glowing, as the gas slams into the thin ambient gas known as the interstellar medium. In the picture, you can see what looks like a complex network of bubble shapes. The "bubbles" glow at the edges, where the actual collision is taking place. The Vela Supernova Remnant is still expanding.
Ann