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The Bubble Nebula - NGC7635

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astrophoto.kevin
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25 days ago5 min read

The Bubble Nebula (NGC7635) is a small Emission Nebula in the constellation Cassiopeia on the northern hemisphere. The "Bubble", which gives the name to this molecular cloud, envolved due to the emission of gas of a big O-star and its star winds. The O-star with the cryptic title BD +60 2522 (SAO 20575) emits large amounts of gas, which are also accelerated by its solar wind. These accelerated gases are colliding with a speed of around 28 kilometers per second with the surrounding molecular cloud, which creates a counter-pressure to the expanding gasses of the star. This process emerges as a shock wave, that is seen as the shell of the bubble.

 
The Bubble Nebula captured with a focal length of 420mm.
NGC6888.jpg
Click on the image for a larger view ▲

As the Bubble Nebula isn't that big and because I only have a focal length of 420mm, I tried to make a drizzled image of the bubble itself.
Drizzle is a method of image processing that can, in this case, upscale the resolution of an image. The single frames need to shift slightly from each other so that the algorithm can calculate/interpolate the pixels. This site explains the process very good: http://www.stsci.edu/~fruchter/dither/drizzle.html

 
The Bubble Nebula drizzled by a factor of 2
NGC6888.jpg
Click on the image for a larger view ▲

Anyway, even the drizzle algorithm is not upscaling images in a perfect way; it also upscales and amplifies noise and other unwanted characteristics.

What else is on the image

In the following picture, I have marked some more or less bright stars and some other interesting objects that are located around the Bubble Nebula. Like the last time, I used the Aladin Sky Atlas suite to identify the stars and objects in the image.

 
Image with names of some objects/stars. Created by hand in Photoshop.
NGC6992_annotaded.jpg
Click on the image for a larger view ▲

 
 

As you can see, there are a lot of objects in the image. One of them is the Open Star Cluster Messier 52, which contains more than 600 stars and has a mass of around 1,200 solar masses. One other is the Emission Nebula NGC7538, which contains the biggest ever discovered Protostar until now. It is about 300 times bigger than our Solar System. You can also see some gigantic clouds of gas and dust named the Lobster Claw Nebula and Sharpless 161.

 
 

Position in the night sky

As mentioned above, the Bubble Nebula (NGC7635) is part of the constellation Cassiopeia. Cassiopeia can be easily found due to the brightest stars that are aligned as a big W.

 
Position of the Bubble Nebula in the night sky. Screenshot of SkySafari Plus app for iOS.
NGC6992_location.jpg
Click on the image for a larger view ▲

 
 

Details of the image

The picture was taken in my Backyard with the following equipment and settings.

Camera QHYCCD247C
Telescope TSAPO65Q · 420mm · f6.5
Filter STC Duo-Narrowband Filter (48mm / 2")
Guide camera QHY5L-II
Guide scope TSL60D · 240mm · f4.0
Mount Skywatcher AZ EQ-6
Exposure time 31 x 600" = 310 minutes = 5 hours 10 minutes
ISO Unity Gain @ -20°C

Everything is controlled by my Astro-PC via remote desktop and wireless LAN.

Software: Sequence Generator Pro, PixInsight, Photoshop CC

 

The license of my pictures

All images, otherwise clearly indicated, in this post are my own work.
You can use it for free if you credit them to @astrophoto.kevin.

 
CC BY-SA 4.0 Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)

 
 

References

https://de.wikipedia.org/wiki/NGC_7635
https://www.universeguide.com/star/hd220369
https://www.universeguide.com/star/hip115691
https://www.universeguide.com/star/4cassiopeiae
https://en.wikipedia.org/wiki/Messier_52
https://en.wikipedia.org/wiki/NGC_7538
https://apod.nasa.gov/apod/ap180419.html
http://galaxymap.org/cat/view/sharpless/157
http://galaxymap.org/cat/view/sharpless/161
http://www.stsci.edu/~fruchter/dither/drizzle.html

 
 

Thank you very much for visiting and reading!

If you have any questions or suggestions, please don’t be afraid to let me know of anything you thought about this post in the comments below!

Yours, @astrophoto.kevin

 
 

 
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