Quote:
|
Originally Posted by Paradise Lost
Umm, I don't think this could be right. A Red Supergiant star is releasing
ALOT of energy, but for the most part, it's no where near the temperature of
lets say, a Blue Giant (the hottest type of star I know of.)
Also, the only things producing reactions in the star, as far as I know, are
deep in the core, and consist of Hydrogen fusing together to make Helium,
sometimes with something left over.
|
You are partly correct. A red giant produces more energy than a white dwarf. But a red giant is huge, we're talking as big as the orbit of mars, so the energy is more spread out, so the temperature at it's surface is lower than that of a white dwarf. The dwarf produces less total energy, but it's only the size of a city, so the temperature at it's surface is very high.
Yes, the only thing producing energy is nuclear fusion in the core, but the rate at which it fuses hydrogen is a function of a stars mass. A more massive star has more gravity, which pulls the molecules in harder. More pressure means a faster rate of fusion, which means more energy. More massive stars burn hotter, and are usually blue in color. A mid sized star like our sun isn't quite as hot and is yellow. A low mass star will be red dwarf.
Red giants are a different thing, though. When a sunlike star fuses enough hydrogen into helium, it will start fusing the helium. Helium fusion produces a lot more energy. The star's gravity can't overcome this energy, so the star expands. It is producing a lot more energy, but at it's surface, it's spread out over a larger area so it's not as hot at the surface, and thus it's red color. When the red giant is done fusing helium, it's done. No longer producing any energy, it colapses into a white dwarf. Not puting out nearly as much energy, but much lower surface area, and thus hotter at the surface.