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Object name
NGC6888 the Crescent nebula

Constellation: Cygnus
Distance: 5 000 light years
Imaged by Jean-Yves Beninger from Alqueva Dark Sky, Portugal
From 28 to 30 September 2024

Equipment:
Astro-Physics Mach1
Astro-Physics AP130 Starfire EDF with 2.7" field flattener 67PF562, 819mm
Camera Zwo ASI 2600MM pixel size 3.76µ
Filters R, G, B, S, H, O

HOO image

Description:

The Crescent Nebula is the result of stellar mass loss from WR 136, a Wolf-Rayet star in the final stages of its life. About 250,000 years ago, this massive star began shedding its outer layers, ejecting material at an incredible rate. As the fast-moving stellar wind from WR 136 (blowing at speeds of around 2,000 km/s) collides with the slower-moving material ejected in its earlier red giant phase, it forms a shell of ionized gas, creating the nebula’s distinctive crescent shape.

The nebula itself spans about 25 light-years in diameter and glows due to the ionization of hydrogen, oxygen, and sulfur gases. The complex structure consists of filamentary and clumpy features, sculpted by turbulent interactions and magnetic fields.

WR 136 is a massive Wolf-Rayet star, a rare type of hot, evolved star that has shed its hydrogen envelope and is exposing its helium core. It is around 15 times the mass of the Sun but is losing mass rapidly due to its intense stellar winds. Eventually, WR 136 is expected to end its life in a supernova explosion, leaving behind either a neutron star or a black hole.