The Crescent Nebula and the Soap Bubble Nebula

In this image, taken by +Nicolas Kizilian using a William Optics Zenithstar 66 Telescope and a Moravian G2-8300 camera, you can see the Crescent Nebula (NGC 6888, Caldwell 27), a Wolf–Rayet type emission nebula, and the Soap Bubble Nebula (PN G75.5+1.7), a planetary nebula. They are both located in the constellation of Cygnus (The Swan https://goo.gl/g6As1j), NGC 6888 is about 5.000 light-years away from Earth.

The Crescent Nebula is clearly visible in the image, the Soap Bubble Nebula is harder to find, it is located a little below the center of the image and is very small and faint.

NGC 6888 is driven by the Wolf-Rayet star WR 136 (HD 192163, https://goo.gl/cl3PC8), a red supergiant (https://goo.gl/fz1C03) star estimated to be 250,000 times brighter than the Sun, 15 times more massive, and 3.3 times larger.

The Crescent Nebula was discovered in 1792 by the British astronomer Friedrich Wilhelm Herschel (https://goo.gl/E9YsKH). The Soap Bubble Nebula was discovered June 19th, 2007, by amateur astronomer Dave Jurasevich (https://goo.gl/i7y6GD).

More information here:
https://en.wikipedia.org/wiki/Crescent_Nebula
https://en.wikipedia.org/wiki/Soap_Bubble_Nebula

The image was made from data acquired between May 24th and May 26th, 2017, total exposure time is nine hours.

What is a planetary nebula?

A planetary nebula is an emission nebula (https://goo.gl/QtI28t), it is basically a shell of glowing ionized gas ejected from old red giant stars and driven by the ultraviolet radiation of the emerging young and hot white dwarf (https://goo.gl/HGYVfx). They are short-lived objects, lasting a few tens of thousands of years until the white dwarf has cooled down so much that its not putting out enough ultraviolet radiation anymore and the gas no longer gets ionized. More here:
https://en.wikipedia.org/wiki/Planetary_nebula
https://en.wikipedia.org/wiki/Red_giant
https://plus.google.com/+PierreMarkuse/posts/diXGtuEkAFE

Videos explaining planetary nebulae:
https://youtu.be/pQ4-m1vtTmE
https://youtu.be/4AT9ct-2-Rc

What is an emission nebula?

An emission nebula is a cloud of ionized gas (often by ultraviolet radiation from nearby stars) emitting light of various colors, in case of HII mostly reddish-pink (if viewed in natural colors). More information here:
https://en.wikipedia.org/wiki/Emission_nebula
https://en.wikipedia.org/wiki/H_II_region

Read more about the different types of nebulae here in this article I wrote for PhotographingSpace:
https://photographingspace.com/what-are-nebulae/

And in case you want to know more about colors in astrophotography, take a look here:
https://photographingspace.com/ap-color/

Image credit: La nébuleuse du croissant et la nébuleuse de la bulle de savon +Nicolas Kizilian https://goo.gl/XByRWx Used with permission

If you like this image, you can find Nicolas here on G+ (+Nicolas Kizilian), on Twitter (https://twitter.com/NKizilian) and on Facebook (https://www.facebook.com/NicolasKizilian) and see more of his work here on his website:
http://www.astropixels.fr

Thank you for your interest in this Astronomy/Astrophysics collection. Maybe add me on Google+ (+Pierre Markuse) and Twitter (https://twitter.com/Pierre_Markuse) or have a look at the Space/Space Technology collection here: https://goo.gl/5KP0wx

#science #astronomy #astrophotograpy #emissionnebula #planetarynebula #space #photography #ngc6888
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