Centaurus galaxy cluster. Coloured Chandra X-ray telescope image of the Centaurus galaxy cluster. Colour-coding reveals the temperature of the gases in the cluster: the coolest are red, through yellow then green to the hottest, which are blue. The long plume of gas (green, centre to upper left) is several million degrees cooler than surrounding gases. Its origin is unclear. It may have formed from debris stripped from a galaxy that fell into the cluster, or it may be gas pushed out of the cluster by an explosion in the central galaxy. However, its composition is no different to that of the surrounding hotter gases.