An Interesting Field Indeed

The open star cluster, NGC 6823, at the image center has 30 stars of 9th magnitude and fainter in a region about 50 light-years across. The cluster is 7500 light-years away, and only three million years old. It is dominated by many young, bright blue stars tightly bunched into a space of one square light-year. However, the outer parts of the cluster have even younger stars.  

Vulpecula OB1. The cluster is the core of the much larger Vulpecula OB1 stellar association, which is hundreds of light-years across, in our view about 1.5⁰ x 3.5⁰. OB associations consist of groups of young O and B stars that are not gravitationally bound. These clusters are the birthplaces of stars, including the most massive and the least massive.

An HII emission nebula: Sharpless 86 (SH2-86) also known as Lynds 135 (LBN 135) surrounds the star cluster. The nebula is contoured and also excited into visible red Ha fluorescence by the OB stars in the cluster.  This emission nebula is sometimes called NGC 6820, but NGC 6820 actually refers to a small emission nebula, which is a knot in SH2-86. See Simbad for more information.

The elephant trunk or pillar is much like the more famous Pillars of Creation: dense cold gas shaped by the winds and radiation of young stars. The pressure on the surface of these pillars triggers more star formation there.

Bok Globules are cold dark molecular gas at about 10 Kelvin, and can be from 1 to 1,000 solar masses and 10,000 au to 3 light-years in size. Globules are a stage in the collapse of a dense part of molecular clouds that are forming new stars. Bok Globules may represent the collapse of the densest part of an elephant trunk.

A small unresolved star cluster, Collinder 404, and emission nebula centred at about the same spot, NGC 6820,  is obvious as a white patch at 5 o’clock. It is described as a knot in SH2-86, about 0.5x0.5’ in size. Variable stars that are Cepheid candidates are present, but none of them have been identified as Cepheid variables to date.

My imaging is a total integration of 46 hours, the first 30 hours with an  L-eNhance HO filter, the last 16 hours with an L-eXtreme HO filter. The L-eNhance sometimes does a better job bringing out the blue in nebula, while  the L-eXtreme does a better job with LP, giving me much darker background and better contrast. I often used both for an image. Much of the imaging was affected by light smoke in the upper atmosphere, so most nights had somewhat marginal transparency due to smoke. Many other nights had heavier smoke that prevented imaging. 

My processing: I calibrated and stacked in DSS. In StarTools I did a background wipe, 2X bin, digital development stretch, HDR, deconvolution, initial color, star reduction, and superstructure isolation. Finally in Photoshop I used StarXterminator to isolate stars and nebulosity to separate layers (it did an amazing job, even with so many bright and also faint stars!). To the nebulosity I applied APF-R (a multi-scale unsharp mask used by NASA) to bring out detail. To both the star and nebulosity layers I applied separate noise reduction with NoiseXterminator and also a color adjustment. The stars were added back in with a linear dodge (add).