Friday, February 28, 2014

The Medusa Nebula

The Medusa Nebula (or Abell 21) is a planetary nebula in a distance of 1,500 lightyears in the constellation Gemini. It was discovered fairly recently (1955) and it was first thought to be a supernova remnant. It has its name from the braided serpentine filaments of glowing gas which look like the serpent hair of the Medusa (from the Greek Mythology).
(click on image for acquisition detail)

I had to use GradientXTerminator to remove some gradients in the Ha, SII and OIII images. I used a star mask to whiten the stars and Carboni's astronomy tools to add some fraction spikes.