Freezeflame Galaxy is one of the worlds in Super Mario Galaxy. It consists of a piece of frozen water, ice, and hot magma, making it highly versatile. It's orbited by Cosmic Comet and the Purple Comet, and contains six Power Stars; three of them bring regular Stars, two of them being Comet Stars, and one hidden Power Star.
This hidden Power Star can be found at the "Frozen Peak of Baron Brr" - Baron Brr being the only boss in the level - where Mario has to grab the Ice Flower, and jump up the leaking pipes. Mario needs to Wall Jump onto the mountain side and grab the edge. (Mario can, however, only grab the edge once he's back to his normal self.)