Sh 2-284 is a major star formation region ionised by the star cluster Dolidze 25 and believed by most authorities to lie in the Milky Way's Outer arm.
Celestial north is to the right.
This is a five colour composite image. One colour (light blue) is assigned to the SuperCOSMOS hydrogen-alpha data and four colours to data from the channels of the Spitzer infrared telescope IRAC instrument (channel 1: bright green, channel 2: yellow, channel 3: orange, channel 4: red). The Spitzer data for this region is described in a 2007 paper.
One intriguing aspect of this image is the way in which it shows that the hydrogen-alpha emission that dominates visual images of this region is largely confined to cavities created by the ionising stars of Dolidze 25. New stars are forming in the warm cavity rims that are invisible to optical observers. After seeing the infrared images of this region I feel that the visual images are but a fading smile and that Spitzer has finally shown us the full Cheshire cat.
You can also view a detailed image of the finger-like pillar in the central cavity here.
The fine print:
Use of the SuperCOSMOS data is courtesy of the UK Schmidt Telescope (copyright in which is owned by the Particle Physics and Astronomy Research Council of the UK and the Anglo-Australian Telescope Board) and the Southern Sky Survey as created by the SuperCOSMOS measuring machine and are reproduced here with permission from the Royal Observatory Edinburgh.