In place of an astronomy observation, I decided to listen to a podcast from astronomycast.com on my favorite celestial object- the nebula.
Dust and gas compose the beautiful nebulae that we all see in pictures. One of the speakers of the podcast denoted them as "everything-" having to do with stars, I think. They are huge.
Cold temperature condenses regions, keeps them dark. With emission and reflection nebulae, however, the heated gas gives off light in different colors.
I learned that if you're seeing a star "on the other side of the nebula," you're going to see it as red. But if you see one off to the side, you see the blue and the green (in reflection nebulae).
When you crank the energy up, that's when you get emission nebulae. In emission nebulae the stars also tend to be embedded in the cloud of gas. -I am now less confused about the differences between the types of nebulae- Reflection nebulae are cooler, emission ones are hotter.
The light we see does not come directly from the stars, but from absorption lines, where the light is re-emitted. We see oxygen lines in planetary nebulae, as they are still hot.
Gas becomes tens of thousands of degrees, and gravity pulls the gas together, but something has to cause it to collapse.
The bubble structures we see in nebulae are stars beginning to ignite and blow matter around them. And to see stars forming within them, we need infrared light.
The female narrator discussed stars that were likely to go supernova, and star clusters that show what our Sun may have looked like during its formation. Planetary nebulae and supernova are the forms of dead stars, on the other hand. The crazy shapes we see in nebula are defined by the physics of how the gas is moving. Some nebulae form over long periods of time (brightening, expanding, fading...), others form in a sort of "splat," depending on the stars.
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