The Blue Snowball Nebula, NGC 7662 or Caldwell 22, is at its core, one of the brightest planetary nebula's, but small, about the size of Jupiter--thus legitimately earning its "planetary" name. As for the blue part of its name, it is strongly blue-green from OIII, but actually appears very green in my raw captures--no doubt due to the 2x green pixels for every blue and red pixel--this is one issue with an RGGB camera. (Astro cameras after all are still based on consumer CMOS chips that continue with the RGGB format--though I am not sure why we still need double G pixels, given what can be done in software--my guess is backward compatibility is the concern? With that, my rant for today is done.)
My processing turned down the green, to enable a wider range of color from the nebula, in particular to highlight the red Ha, as well as subtle blue to green color changes in the nebula. The inner portion sports red Ha as well as a bright green OIII shell, in places broken by the Ha. This is followed by a bluer and dimmer shell--bluer to reflection (?)--and then more Ha scattered around the edge of that bluer ring. Finally, a dimmer halo is much bluer on the outer edge, not captured in images unless there is more exposure--I have deliberately enhanced that, while dimming the core. Hopefully I have captured the subtleties' of this fascinating snowball--though it looks more like a blood-shot eye to me.
As for the Blue Snowball's location in space-time, it is challenging to calculate distances to most planetary nebula, as there is no standard "candle" for reference. But estimates put the Blue Snowball between 2,000 and 4,000
light-years away, and thus it has an actual diameter of between 0.35 and 0.70 light-years.
My processing included a 3x drizzle in DSS to tease out as much resolution as possible.
Comments