Nebulae
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The Eye of God - A Deep View into the Helix Nebula (NGC 7293)
This deep view of the Helix Nebula combines light from traditional LRGB filters together with specific narrow Ha and OIII wavelengths to reveal the colourful and complex structures of this magnificent planetary nebula.
The Helix Nebula is located around 700 light years away towards the constellation Aquarius. It is one of the nearest planetary nebulae and therefore appears quite large and detailed although its surface brightness is rather low.
The nebula is the result of a sun-like star shedding its outer layers during its final stages of evolution. Several rapidly expanding shells of dust and gas surrounds the intensely blue stellar remnant in the centre, giving the appearance of a giant eye in space. The inner and outer shells were expelled from the star approximately 6,500 and 12,000 years ago respectively and are expanding at a speed of 32-40 kilometres per second.
The brightest ring is currently two light years across, while the faint outer structures extend to a diameter of four light years - the same distance as between the Sun and the nearest other star; Alpha Centauri.
Powerful ultraviolet radiation from the central star is shredding the nebula and exposing many long trailing knots of denser material radiating out from the core. Images from the Hubble Space Telescope have revealed up to 20,000 such knots in the Helix Nebula alone, and similar structures have been observed in other planetary nebulae.
The central stellar remnant is no longer emitting light from nuclear fusion, and is now only glowing with the remaining heat from the once stellar core. It will eventually cool down and become a white dwarf star, and the entire spectacular vista of the Helix Nebula will slowly dwindle away as the dust and gas continues its rapid outward journey away from the small fading white dwarf star in the centre.
In the background numerous distant galaxies appear as tiny smudges, a billion light years away or more. Several of these galaxies are even visible through the nebula itself.
Image details:
Date: July to November 2018
Exposure: (L Ha OIII R G B) 570:1065:450:170:75:70 mins, total 40 hours @ -25C
Telescope: Homebuilt 12.5" f/4 Serrurier Truss Newtonian
Camera: QSI 683wsg with Lodestar guider
Filters: Astrodon 3nm Ha/OIII and LRGB E-Series Gen 2
Taken from my observatory in Auckland, New Zealand
