You seem to be asking for a video camera that can film in almost total darkness, and film stars? Short answer, the C6 might be a teeny bit better, but not enough to do what you want.
Longer answer, don't forget that since the frame rate is only 1/30 second (30 frames per second) that they camera can't use a very long exposure. Your choices are...
1) Nightshot, like Sony uses. That uses an infra red illuminator on the camera to film monochrome infra red video. Obviously your typical, ah, "UFO" is too far away for you to light it up with a tiny light on a camera.
2) Light amplification systems, like the military uses using photomultiplier tubes. Really expensive and monochrome.
3) A really big lens on your camera. Very expensive.
There aren't too many cameras to choose from to film stars, and they are all going to be super expensive.
You should probably read up on what you want to do before you spend thousands on equipment.
p.s. If you want to film astronomical things, use manual focus, the camera will not be able to focus in such low light.