Hi;

The pictures in the books may or may not show the true color of the Sun - most of its light is emitted in the yellow/green part of the spectrum.It appears yellow to us at the surface of the Earth because our atmosphere scatters the blue light (which makes the sky look blue), leaving more of the rest (yellow, toward red) behind to make the Sun appear yellow.

As I mentioned in my post about the color of sunspots, scientists will often use "false colors" from the computer programs we work with to show images, and the color coding help us quickly identify the data we are looking at and maybe some characteristics about it. For example, if you look at the images at http://sdowww.lmsal.com/suntoday/, the images taken in X-rays (which our eyes can't see at all) are color-coded, and it indicates something about the temperature of the structures that we see.

Cheers, -KD