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Contains:  Crescent nebula, NGC 6888
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NGC 6888, Crescent Nebula (bicolor, WIP), 


            Ruben Barbosa
NGC 6888, Crescent Nebula (bicolor, WIP)

NGC 6888, Crescent Nebula (bicolor, WIP)

Technical card

Imaging telescope or lens: GSO 8" f/5 Newton

Imaging camera:Moravian G2-8300FW

Mount:SkyWatcher NEQ6 Pro Goto

Software:Maxim DL, Gimp

Resolution: 3201x2341

Ha: 11x600" bin 1x1
OIII: 19x900" bin 1x1

Integration: 6.6 hours job: 1643734

RA center: 20h 12' 2"

DEC center: +38° 22' 30"

Pixel scale: 1.220 arcsec/pixel

Orientation: 91.018 degrees

Field radius: 0.672

Data source: Public amateur data


* Image acquisition by: Thomas Richter.
* Processing: Ruben Barbosa.

The Crescent Nebula (also known as NGC 6888, Caldwell 27, Sharpless 105) is an emission nebula located in the constellation of the Swan and is about 5,000 light-years away.

The NGC 6888 shown here results from the combination of narrowband data, where the wavelengths of hydrogen (in reddish tones) and oxygen (in blue) were isolated. A longer exposure of OIII would reveal delicate filaments surrounding the nebula.

As is well known, all bright objects have a source of energy responsible for this brightness. The question we can ask is: what will be the mechanism responsible for its structure and brightness?
The answer is WR 136; The central star of the Wolf-Rayet type of NGC 6888, a very massive object (with more than 20 solar masses) that has been losing its mass quickly by very strong solar winds. In this case, it is estimated that every 10,000 years, the WR 136 loses the equivalent of the mass of the Sun.

The complex structures of the nebula are probably the result of the interaction of this strong wind with the material ejected earlier, about 400 thousand years ago, when it was in the red giant phase. Currently, the WF 136 expels its outer layers into space at speeds in the range of 2,000 to 3,000 km/s, causing them to collide with the gas layers lost in the red giant phase that are now moving towards the star. These shock waves energize the gas, giving rise to X-ray emissions.

Once these stars live intensely, they eventually evolve into short spaces of time. When the WR 136 ends nuclear reactions, it will evolve into a spectacular supernova.

Even if the reader can not observe this nebula, this beautiful region of the sky offers us various objects of interest.

See also:



Ruben Barbosa
License: None (All rights reserved)

Sky plot

Sky plot


NGC 6888, Crescent Nebula (bicolor, WIP), 


            Ruben Barbosa