NGC6820 / Sh2-86 in HST

swag72

swag72

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Sara
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NGC 6820 is an emission nebula that surrounds open cluster NGC 6823 in Vulpecula. The nebula NGC 6820 is also called Sh 2-86.

The most striking feature is the trunk-like pillar of dust and gas protruding from the east side of the nebula. The huge pillars of gas and dust are probably formed when surrounding gas and dust is pushed and eroded away by radiation from nearby stars. NGC6820 lies about 6000 light years away.

This is a combination of 31 x 30 minute exposures using three filters that are very specific in their waveband pass. 15.5 hours of total exposure.

NGC6820 (Sh2-86) in bi colour by swag72 (www.swagastro.weebly.com), on Flickr
 
Another very good image from you Sara.... how do you know what filters to choose to give the best effect?.
 
Wow still amazes me you can pick something up so far away with such detail, are these the colours that are really there? Or use of filters manipulates what colours come through?

Kellett
 
Thanks for your comments - Regarding what filters to use, I know that some specific targets (such as emission nebula) will be good with certain filters. In the same vein there's no point using some of these filters on a galaxy, you'll pick up no detail at all.

Generally my images are false colour - That is that they are combined in a traditional hubble pallete to get the colours.
 
Another cracker there Sara.

For thse trying to understand what they're seeing, the reason these techniques work well on nearby nebula and not on other galaxies is essentially a question of contrast. The filters Sara uses are narrow in wavelength to pass only specific emission lines (generally, though not exclusively, ionised hydrogen and sulphur and doubly ionised oxygen like in this image). These appear bright because there is relatively little continuum emission in behind. A galaxy is sufficiently far away that the "background" to any line is always full of stars in the galaxy, so the emission line/continuum ratio is dramatically reduced. Best to just use broad band for galaxies.
 
Beautiful work yet again, and a lot of hard work as well. Your images are truly stunning.
 
ROFL! :D
 
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