As for your question, you mentioned magnification on the Big Dipper picture. Did you shoot that through a slightly defocused telescope or was your lens slightly defocused? IIRC (orionid correct me if I’m wrong), it’s only very recently that they’ve been able to visualize another star other than our sun, and they can’t do that with ground based amateur telescopes. Due to distance and resolving power, stars generally are just point sources of light, even through a telescope. I would guess that the color in the magnified version would be some combination of the star’s color, the underlying process of digital image capture, atmospheric conditions, and possibly some chromatic aberration from the optics. Your Big Dipper stars looked to me like the lens or telescope was slightly defocused to create the bigger/round stars effect (which is cool, btw), but either way, you aren’t seeing star surface there.
You pretty much hit it right on there. Stars are always point sources, even the closest ones. Unless you’ve hired hubble time, or one of the other serious deep-sky scopes like the ones at Mauna Kea or Goldstone. Mopsy, the effect you’re seeing is from being slightly out of focus, although, that is a technique often used by amateur astronomers to determine the spectral qualities of a star. Brighter magnitudes make bigger circles, and the color is alot easier to see in its blurry, bulbous form.
