M27 on 2013-06-18
Messier 27, the Dumbbell Nebula, taken from suburban Dallas on a night with 80% – 90% humidity with the object in the light dome of a massive shopping complex just a mile away. Yes, you can practice astrophotography in the city! This image was built from 41 minutes worth of 60 second sub-exposures stacked one on top of the other with some other frames to subtract various forms of noise.
At an average estimated distance of 1,250 light years this planetary nebula is relatively close. Several thousand years ago the parent start ejected its coronal mass and collapsed into the white dwarf in the center of the nebula. This is the same fate our star will have some 6 billion years from now. M27 has a visual brightness of magnitude 7.4 which makes it visible as a grey hourglass shape in small (80mm refractors, 114mm reflectors) telescopes at moderate magnifications. The central star itself does not emit very much visible light so what we’re seeing is gasses that are excited by infrared or x-ray radiation. Hydrogen Alpha glows red and doubly ionized Oxygen (O-III) glows green. These colors aren’t detectable by the human eye but through the magic of technology we can pull that color out.