2023: Missouri – NGC 6914 – Reflection Nebula Complex – also known as Bluebird Nebula

NGC 6914 is a Reflection Nebula in the Cygnus Constellation, it is situated north of the celestial equator and, as such, it is more easily visible from the northern hemisphere.

Rookie mistake, I left my camera gain at 300 

 –  I should have spent more time on this region.

The NGC 6914 Nebulae Complex

The nebular complex know as NGC 6914, in the Cygnus constellation, is a clear case of combination of the three types of nebulae described below. This region concentrates gaseous and dusty masses of the galactic plane, where stars are born. Fragments of nebula situated between the Earth and the young stars appear to be dark, with varying opacities and intricate shapes. In other areas, near the younger and hotter stars, dust shines with the bluish colors of the reflection nebulas. Lastly, all the image is covered by ionized hydrogen that gives to the scene a reddish and warm backdrop. Newly born stars, which are only a few million years old, mill around the scene. Their colors reveal their diversity of masses and temperatures. But in this small portion of the Galaxy, about 6,000 light-years away, massive and hot stars (O and B type stars) are so abundant that the area is classified as an OB association. Its name is Cygnus OB2.

Interstellar Nebulae

Almost all the universe is made up of hydrogen and helium, thus composed of light and simple atoms; and interstellar nebulae aren’t an exception. But the interstellar medium is made up in a small part of other materials like carbon, silicon and oxygen. These materials tend to aggregate, building tiny grains that form what we know as interstellar dust. Thus, a normal nebula is made up of a 99% of gas (hydrogen and helium) and a small proportion of material that composes the dust.

Interstellar Dust and Light

Interstellar dust is a small part of a nebula, but its interaction with light is so intense that it defines their shape. Light that reaches the dust is partially scattered and partially absorbed. This phenomenon is like what happens with the clouds of the Earth’s atmosphere: the water droplets and the tiny ice crystals reflect and scatter part of the light hitting them. That’s why, due to reflected light, the clouds have a bright appearance when looked from the same side as they are illuminated. However, when the same clouds are observed from the opposite side, light is absorbed proportionally to their density and thickness. That’s why, when looking from below, we can see the Sun dimmed by the clouds. In the latter case, clouds appear to be deep gray.

The role of cosmic dust with stellar light is similar. A nebula containing a small quantity of dust will look darker, or even black, when illuminating stars are in the background. Then, we talk about dark nebulae. This same nebula, observed from the side where light is reflected, will appear bright. The interstellar dust is less reflective than the atmospheric clouds, but when the light from hot young stars reaches the dust, it shines with light blue tones. This is what we know as reflection nebulas. The blue cast of a reflection nebula is not only due to the color of the hot stars, but to the interaction of light with the dust grains that favors the reflection of blue light.

Gas Light

Nebular dust always comes with gas — mostly hydrogen gas. The same massive hot stars that illuminate the dust can cause the pure gas to shine. Ultraviolet light from the most massive stars pulls out electrons from the hydrogen atoms. When these atoms get back their electron, they emit a characteristic reddish or pinkish light: the H-α and H-β radiation. This excited gas forms the emission nebulae, which are a main feature of the star forming regions.

This night was a test, I wanted to see how this region would appear in Hydrogen Alpha, so I used a new filter and while I made a mistake, I was pleased with the overall output.

Integration: 2h 5′ | Darks: 20 | Flats: 20 | Flat darks: 20
 Avg. Moon age: 15.99 days | Avg. Moon phase: 98.32% 
 Bortle Dark-Sky Scale: 5.00 
Inspiration – I saw the post shared by James, the DSO Imager on YouTube – https://www.youtube.com/c/DSOImager

Until the next adventure and thank you for stopping by!

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