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Saturday, August 13, 2011

Bubble Nebula, apparent scale in the sky, horizontal editions

I have shot many targets with several focal lengths. 
Due that, I will publish some of my material as an image sets, with different field of view and detail levels.
The fractal nature of our universe stands out nicely by this way and it will make the orientation more easy.

Many times, it's difficult to understand the image scale of astronomical images.
Due that, I will add a Moon circle in some of the images to show the angular scale in a sky. 
The full Moon has an angular size of ~30 arc minutes, that's equal to ~0,5 degrees. 

Sharpless 162, NGC 7635, the "Bubble Nebula"
Ra 23h 20m 48s Dec +61° 12′ 06″

Natural color composition from the emission of ionized elements, R=80%Hydrogen+20%Sulfur, G=100%Oxygen and B=85%Oxygen+15%Hydrogen to compensate otherwise missing H-beta emission. This composition is very close to a visual spectrum.

NOTE. The size of the full Moon (0,5 degrees) is marked as a scale.

NGC 7635 aka "Bubble Nebula, Sh2-162 or Caldwell11, is a Hydrogen emission nebula in constellation Cassiopeia. It locates near the open cluster M 52 at distance of about 11.000 light years from the Earth.
The bubble structure is created by a strong stellar wind, a radiation pressure, from massive hot magnitude 8,7 central star, SAO 20575, it can be seen in an image inside of the bubble, off centered at Right.
Bubble is an expanding shock front inside a giant molecular cloud and it has a diameter more than Six light years. The spherical formation is expanding at speed of 6500.000 km/h, due the huge scale and distance we can't see the movement easily. In a century, the bubble in this image will be only about one pixel wider, than now! ( ~1 arc second)
Strong UV-radiation from a central star ionized elements in a gas and makes them glow at typical wavelength to each element. (Hydrogen glows Red light as Sulfur, Oxygen emits Green/Blue light at visible wavelengths) 
If you are interested about color schemes used in my images, I wrote a small study about them, please, have a look here:

Images are in HST-palette, (HST=Hubble Space Telescope)
from the emission of ionized elements, R=Sulfur, G=Hydrogen and B=Oxygen.
Star colors are mixed from the NB channels, Red=H-a, G=O-III and B= 85%O-III + 15%H-a.
NOTE. The size of the full Moon (0,5 degrees) is marked as a gray circle in all of the images.

Images used in the series above from Left to Right
  1. A wide field mosaic from the Bubble and Sharpless 157 to the Wizard Nebula at Right. Images are taken with a Tokina AT-X 300mm camera lens. 
  2. A Sh2-157 and Bubble Nebula part of the mosaic, Tokina AT-X 300mm 
  3. Zoomed in version from the previous image 
  4. A close up of the Bubble Nebula imaged with a Meade LX200 GPS 12" telescope, focal lenght ~2000mm. 
  5. A zoomed in version of image above.
Links to the original images, used in series, from top to bottom

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