AAO image reference UKS 10. « Previous || Next »
Top left is NE. Image width is about 2.9 degrees
Image and text © 1979-2010, Australian Astronomical Observatory
Photograph from UK Schmidt plates by David Malin.
Most photographs of regions of the nebulae around star-forming regions show that the red nebulosity is associated with one or more very hot, bright stars: these same stars are responsible for the ultra-violet radiation which ionises the hydrogen atoms. This absorbed energy is eventually liberated as a few distinct wavelenghts of (mostly) visible light, the strongest of which is in the red part of the spectrum.
In addition to the deep red hue, other wavelengths contribute to the overall colour. Most prominent are lines in the blue part of the spectrum, so the normal colour of a star-forming region is therefore usually magenta, a bluish-red colour, the exact shade depending on the amount of blue light present. However, the star-forming nebulae NGC 6334 and 6357 pictured here are buried in the plane of our Galaxy in the direction of Scorpius, and are seen through thick dusty clouds. The dust both scatters and absorbs blue light along our line of sight, giving these nebulae a deep red hue. The effect of Galactic dust on the colour of emission nebulae is also seen in NGC 3576 and NGC 3603 in Carina.
Related images
UKS 11. NGC 6334
UKS 12. NGC 6357
AAT 38. NGC 3576 and NGC 3603 in Carina
Constellation of Scorpius (external site)
For details of object position and photographic exposure, search technical table by UKS reference number.