OTA: Star-Fire 175 (f/8)

Camera: FLI - PL16070AE

Observatory: Deep Sky West, NM

EXPOSURES:

…..Red: …….…...…37 x 900sec

…..Blue:……………30 x 900

…..Green:..……….30 x 900

…..Hydrogen:…..39 x 1200

…..Oxygen:……...21 x 1200

Total exposure ~41 hours

Image Width: ~3/4 deg

Processed by Alex Woronow using PixInsight, StarNet, Matlab, Topaz, and others in 2020

(Source: largely Wikipedia: see https://en.wikipedia.org/wiki/Helix_Nebula)

The Helix Nebula is a ‘planetary Nebula’ formed by the death of an intermediate to low-mass star (sun-like), which depleted the hydrogen in its core and began burning hydrogen in a shell around the core. This caused the star to expand greatly into a ‘red giant’ star. But, eventually, the red giant’s core collapsed and became extremely dense. The collapse heated the core (to ~100,000,000 deg K), and suddenly, helium began burning to form carbon, in what is referred to as the ‘helium flash’. This burst of energy caused the ejection of the star’s outer shell to form a planetary nebula. When helium becomes exhausted, an incipient white dwarf has no further sustainable energy source and gradually cools. The small star, seen in the center of this nebula, is the culprit white dwarf for the Helix Nebula. The ionized hydrogen glow (red) and oxygen glow (aqua-blue) arise from the violent formative event and the intense, hot, radiation from the new white dwarf.

The radial structures have been named “cometary knots.” The Helix Nebula is the nearest planetary nebula to earth (~650 light-years) and is the nebula in which these knots were first observed--later observed in other planetary nebulae as well. (Just a note: “Planetary nebulae” have nothing to do with true planets, just a name that reflects their roughly circular/spherical shapes. Similarly, “Cometary knots” have nothing to do with comets. The radial spikes have leading heads of denser gas and a gossamer body--comet-like, at least to some.)