Helix Nebula, NGC 7293

Located in Aquarius, it is the closest known planetary nebula to us (~ 700ly), but is large and of low surface brightness. Radiation emitted by the  extremely hot dying star in the centre causes many shells of gas previously blown off by the star to fluoresce producing the observed colours, predominantly of ionised hydrogen and oxygen.

 
Camera: SBIG STL11000M, Astrodon filters Scope: Takahashi TOA-130, f=1000mm, f7.7 (cropped fov ~0.6°x0.5°)
Mount: Takahashi EM-200 Temma2 Guiding: E-finder
Filters/Exposures: L:R:G:B = 2x15:2x15:2x15:2x15min ≡ 2h00m Location: ASV's LMDSS Heathcote, Victoria
Date: October 2010 Processing: CCDStack2, MIRA AL8 and Photoshop CS5 (reprocessed March 2023)