M33: The Pinwheel Galaxy by Rod Pommier

“M33 is one of the closest spiral galaxies lying at a distance of 2,723,000 light-years. Therefore, it appears large and fortunately also presents us with a nearly face-on orientation. As such, it reads like an open book about all the processes one can see going on in a spiral galaxy within this image. Dark nebulae silhouetted against the galaxy condense into stars, many of which are blue supergiants. Once born, they emit intense ultraviolet radiation which ionizes the remaining hydrogen in the cloud, causing it to glow as an emission nebula at the red hydrogen-alpha wavelength of 656.28 nm. They also emit fierce stellar winds that drive that gas away, and the stars become unbound and spread out as an OB association of blue supergiants. But those blue supergiants live fast and die young as supernovae within a few million years. The shockwaves from those supernovae strike the neighboring dark nebulae and cause them to collapse and the process repeats over and over again. As the galaxy rotates over millions of years, these processes trace out curving blue spiral arms ornamented with numerous red emission nebulae.”

Telescope/Mount: PlaneWave CDK17 on L500 Mount

Camera: SBIG STL-11000M with Baader Planetarium filters.

Location: Pommier Observatory, Portland, OR, USA.

Exposures: Ha:L:R:G:B =480:460:110:110:110 minutes = 21 hours, 10 minutes total exposure at f/6.8