I think the colors are a bit über-saturated...
By the way, if you want to determine the color of a star with non-astronomical digital cam, use bad focus so that the star's image gets smudged over more pixels.
CCDs are sensitive to a wide range of photon energies, from UV to near IR. Once a photon hits the CCD it liberates an electron. The electron is counted, so you know a photon hit the CCD, but you don't know it's color.
The way to get color information is by putting a filter in front of the CCD. In astronomy, usually you put one filter in front of the entire CCD, so only a narrow band of photons gets through - red color photons, for example. Since your object in the sky isn't really moving fast, you can afford to take several images through different filters and then assemble them...
But in day to day photography, your object does move. It's impractical to take several shots of your object. To solve that problem, the day to day CCD cams have a mesh of different color filters in front of their CCD. One pixel will thus register only red, one only blue,...
Because a star is very small and may only cover a few pixels, you may only get a few pixel's worth of color data. If you smudge the image over a wider area, you'll cover more pixels and get more color data that will construct a better real-color image.