September 5, 2013
IC 4628, an emission nebula in Scorpius
Image Credit & Copyright: Michael Sidonio (http://www.pbase.com/strongmanmike2002)
IC 4628 (also known as the Prawn Nebula or Gum 56) is a large, faint emission nebula of about 250 light-years across, located some 6,000 light-years away from Earth in the southern constellation of Scorpius (the Scorpion).
Hot, massive stars, millions of years young within the nearby bright open star cluster NGC 6231 (sometimes called the “Little Pleiades”) radiate the nebula with invisible ultraviolet light, stripping electrons from atoms. The electrons eventually recombine with the atoms to produce the visible nebular glow, dominated by the emission of hydrogen.
Deeply immersed in the Prawn Nebula are three young star clusters which are emanating infrared radiation; these clusters, the last of which is less rich, are cataloged with the initials [DBS2003] 113, 114 and 117.
IC 4628 can easily be photographed with a telescope and filters suited to the detection of ionized hydrogen. The nebula can be found just north of NGC 6231 and south of Antares, in the tail of Scorpius, out of sight from most of the USA and Europe.