NGC 281 is a bright emission nebula in the northern constellation of Cassiopeia located in the Perseus Spiral Arm of our Milky Way. It is a diffuse HII region some 48 light years across where active star formation has created an intense radiation environment that has progressively hollowed out the centre of the nebula. The open star cluster IC 1590 (at the centre of the image), dominated by the massive multiple-star system HD 5005, is the main source of ionising radiation within the nebula. A variety of elephant trunk-like pillars can be seen at the lower margin of the nebula pointing like accusing fingers at the source of their demise. These structures are made up of higher density material that erodes more slowly while the surrounding dark nebula is stripped away. As this higher density material gravitationally collapses it forms yet more stars. Backlit by the glow of ionised gas within the nebula, several small isolated black patches of material are evident. These are known as Bok globules and contain one or more protostars that will eventually become visible once the globule dissipates.
Colloquially, NGC 281 is also known as the Pac-Man Nebula for its visual resemblance through amateur telescopes to the 1980’s arcade game character.
Right ascension: 00h 53m 02.50 | Declination: +56° 37' 03.0" | Distance: 9,200 Light Years
Field of view: 42 x 28 arcmin
Camera: SBIG ST-10XME
Telescope: APM 152-1200ED F/7.9
Guiding: Starlight Xpress Active Optics SXV-LF-AO
Mount: 10Micron GM1000 HPS
Filters: Astrodon Ha (3nm), OIII (3nm)
Exposures: Ha 19 x 20 min, OIII 19 x 20 min
Total exposure: 12.7 hours
Scale: 1.15 arcsec/pixel
Image acquired: 5 nights in October and November 2016
Image capture with MaxIm DL, FocusMax, ACP; Image processed with MaxIm DL; PixInsight v1.8 Deconvolution; Photoshop CC 2015
