Dolphin Head Nebula, Sh2-308

 WR 134, Ring Nebula: Made with narrow band filters, this colorful cosmic snap shot covers a field of view about the size of two full Moons within the boundaries of the constellation Cygnus. It highlights the bright edge of a ring-like nebula traced by the glow of ionized hydrogen and oxygen gas. Embedded in the regions interstellar clouds of gas and dust, the complex, glowing arcs are sections of bubbles or shells of material swept up by the stellar wind from Wolf-Rayet star WR 134, brightest star near the center of the frame. Distance estimates put WR 134 about 6,000 light-years away, making the frame over 50 light-years across. Shedding their outer envelopes in powerful stellar winds, massive Wolf-Rayet stars have burned through their nuclear fuel at a prodigious rate and end this final phase of massive star evolution in a spectacular supernova explosion. The stellar winds and final supernovae enrich the interstellar material with heavy elements to be incorporated in future generation of stars. The blue and red light emission occurs because uv light from the Wolf Rayet star is exciting oxygen and hydrogen gas up to higher energy states and then it drops back down to its ground state with the emission of light at characteristic wavelengths.  Most narrowband images are done in the Hubble palette where Hydrogen is green. However in this image I have made Hydrogen as red and Oxygen as blue green which makes the image almost true color since these are the colors of Hydrogen and Oxygen gas emission. This image is a composite of three images. The center is a mosaic of two images done by the 20″ CDK20 and the outer areas were done by the Takahashi 6″ FS152. There was a total of 80 images over 40 hours for the FS152 and 170 images over 90 hours for the CDK20 with an overall total of 350 images over 130 hours of imaging.