Wednesday, August 14, 2013

Floating in the hydrogen sea

As already mentioned in the previous entry Swan nebulaes strikes back most nebulas are emission or reflection. Large, red hydrogen clouds are the most common emission nebulas. Reflection ones reflects the light of nearby stars, so they can be of different colors. Sometimes in the star neighbourhood there are both hydrogen and dust clouds and we can spot both nebula types in the same sky area. This scenario is presented in the picture below.

In the constellation of Cygnus nearby IC1318A nebula there is object called NGC6914. It blue reflection nebula placed about 6000 light years away. It is just a dust cloud illuminated by collection of young, blue stars, most of which are hidden by surrounding dust. The same dust cloud veils the red emission nebulaes behind and can be spotted as dark clouds. The illuminating stars of the nebula belong to Cygnus OB2 association. It contains about 2600 huge stars spread across 200 light years of space. Most of them are obscured by Milky Way dust clouds in that area known as a Great Rift.
Next picture shows enlarged central fragment of the previous one. Both parts of nebula are identified there and also so called "Boomerang star". Catalog name of this peculiar star is V1515 Cygni and belongs to the FU Orionis family of variable stars. This star display an extreme changes in both magnitude and spectral type. "Boomerang" comes from the small nebula shape that is barely visible in my picture - this nebula can be subject for much larger instruments.
Picture itself has been exposed during three different nights with total exposure time of 8 hours. Setup is as usual these days - GSO 6" newtonian with field flattener and effective focal ratio of f/4.5. Detector is modded Canon 450D working at ISO800. Subexposure time was 5 minutes. Setup guided with short tube guider and QHY5 camera. Postprocessing using Maxim and PS CS2.

Clear skies!

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