NGC 2264 nebulae. Optical image of the NGC 2264 nebulae in the constellation Monoceros. North is at top. NGC 2264 is the hot young star cluster (bright patch at centre left). It is ionising the hydrogen gas in the large gas and dust cloud surrounding it, causing it to glow red. The brightest star in this cluster (above and left of the main glow) is the blue supergiant star S or 15 Monocerotis. The lower left portion of this region contains the Cone Nebula, a triangular dark cloud of star formation. This region is 2600 light years distant. The blue glow (centre right) is the reflection nebula IC 2169.