johnm
11-21-2000, 05:36 PM
Back, many years ago when I studied cosmology and stellar genesis, the theory was that stellar incubators would form on the wave front of an expanding nebula. When a emission nebula forms, it is usually the surface of a giant nova, called a supernova.<br>
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A giant star, usually a red giant, as it begins to run out of fuel, creates a layer of helium that surrounds the core, and separates it from the atmosphere. This helium cannot 'burn' into heavier elements (the temp is too low) and acts like a big blanket around the still hot center. Since the energy within the core has no place to go, it builds up, and gets lighter. At the same time, the helium gets denser because it cools off and doesn't absorb the heat of the core. Eventually, kind of like a lake turning over in the winter, the helium heads for the core and the lighter core heads for the atmosphere. Because it is falling downhill and all headed for the center, the helium collides with itself just like in the core of an immense nuclear bomb. The temperature skyrockets within less than a day, and helium fuses to carbon (the last energy liberating fusion reaction). The resulting plasma expands outward at truly cosmic speed (sometimes as much as .5 or .75 light speed). The interaction of the shock wave thus formed causes a truly cosmic wave front of X-ray, gamma wave, and particulate radiation. Also, it is supposed, a major graviton wave.<br>
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This shock wave rips off the majority of the atmosphere, and leaves a dense mass of burning helium (a white dwarf) as the core. If the star is big enough, it collapses into a neutron star (pulsar or quasar), of if bigger still, it becomes a black hole. Meanwhile the atmosphere of the star is streaming off at incredible speeds into the not quite so void of space.<br>
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As it interacts with the stationary gas of the void, it causes it to glow. The crab nebula is a great example of this. You can see the little hot star that surrounded the tenth century supernova.<br>
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Anyway, there are regions, like the famous "incubator" photo from Hubble, where two gas wave fronts collide. It they trap pockets of gas above a certain radius (actually quite small, in an astronomical sense, about 1 1/2 the size of Jupiter), proto star formation can occur. Once a star begins to coalesce, its gravity draws more gas (fuel) into it and it grows until it runs out of material. The richness of the interstellar medium, and its composition, determines how big it is and where on the main sequence it starts its life.<br>
<br>
Stars that form in older regions of "dust" and gas form more complex elements in their cores, and when they die, these get sent out to form the new stars, and the planets that surround it. Our star, Sol, being a G2 star is pretty far along on the evolutionary chain, as our planets attest to, since you have to get to number 6 (Jupiter) counting the asteroids as almost a planet, before you get to "gas bags" (gas planets).<br>
<br>
BTW, did you know that Jupiter is almost big enough to become a sun on its own? It emits almost more radiation that it absorbs. Think of it as "God's prototype" for the solar system. :)<br>
<br>
Happy Thanksgiving!<br>
<br>
John M.<br>
+++++++++++++++++++++++++++++++++++++++<br>
Reality is fractal. It has a pattern with no discernable pattern. The finer you divide it, the more it remains the same.<br>
<br>
A giant star, usually a red giant, as it begins to run out of fuel, creates a layer of helium that surrounds the core, and separates it from the atmosphere. This helium cannot 'burn' into heavier elements (the temp is too low) and acts like a big blanket around the still hot center. Since the energy within the core has no place to go, it builds up, and gets lighter. At the same time, the helium gets denser because it cools off and doesn't absorb the heat of the core. Eventually, kind of like a lake turning over in the winter, the helium heads for the core and the lighter core heads for the atmosphere. Because it is falling downhill and all headed for the center, the helium collides with itself just like in the core of an immense nuclear bomb. The temperature skyrockets within less than a day, and helium fuses to carbon (the last energy liberating fusion reaction). The resulting plasma expands outward at truly cosmic speed (sometimes as much as .5 or .75 light speed). The interaction of the shock wave thus formed causes a truly cosmic wave front of X-ray, gamma wave, and particulate radiation. Also, it is supposed, a major graviton wave.<br>
<br>
This shock wave rips off the majority of the atmosphere, and leaves a dense mass of burning helium (a white dwarf) as the core. If the star is big enough, it collapses into a neutron star (pulsar or quasar), of if bigger still, it becomes a black hole. Meanwhile the atmosphere of the star is streaming off at incredible speeds into the not quite so void of space.<br>
<br>
As it interacts with the stationary gas of the void, it causes it to glow. The crab nebula is a great example of this. You can see the little hot star that surrounded the tenth century supernova.<br>
<br>
Anyway, there are regions, like the famous "incubator" photo from Hubble, where two gas wave fronts collide. It they trap pockets of gas above a certain radius (actually quite small, in an astronomical sense, about 1 1/2 the size of Jupiter), proto star formation can occur. Once a star begins to coalesce, its gravity draws more gas (fuel) into it and it grows until it runs out of material. The richness of the interstellar medium, and its composition, determines how big it is and where on the main sequence it starts its life.<br>
<br>
Stars that form in older regions of "dust" and gas form more complex elements in their cores, and when they die, these get sent out to form the new stars, and the planets that surround it. Our star, Sol, being a G2 star is pretty far along on the evolutionary chain, as our planets attest to, since you have to get to number 6 (Jupiter) counting the asteroids as almost a planet, before you get to "gas bags" (gas planets).<br>
<br>
BTW, did you know that Jupiter is almost big enough to become a sun on its own? It emits almost more radiation that it absorbs. Think of it as "God's prototype" for the solar system. :)<br>
<br>
Happy Thanksgiving!<br>
<br>
John M.<br>
+++++++++++++++++++++++++++++++++++++++<br>
Reality is fractal. It has a pattern with no discernable pattern. The finer you divide it, the more it remains the same.<br>