SH2-308 The Dolphin Head Nebula 7h15 CHI-2 and CHi-4 Bundle

The great SH2-308  emission nebula lies  about 5,200 light-years away in the constellation Canis Major.
It is a famous example of “space bubble” (like Thor's Helmet NGC 2359 or the Bubble nebula NGC 7635) created by the intense radiation of a bright and very hot Wolf-Rayet central star.  Fast winds from this Wolf-Rayet create the bubble-shaped nebula as they sweep up slower moving material from an earlier phase of evolution.
The Dolphin Head covers slightly more of the sky than a Full Moon, which corresponds to a diameter of 60 light-years at its estimated distance.

Another faint bubble is visible at the bottom which is the planetary nebula PNG 234.9-09.7

FOV is about 1x1 degree and scale is 0.98"/pix.

HOO-RGB processing made with Pixinsight and Photoshop.