SH2-155, RGB OOH of cave nebula (Tim Hawkes)

Celestial hemisphere: Northern · Constellation: Cepheus (Cep)

SH2-155, RGB OOH of cave nebula, Tim Hawkes

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SH2-155, RGB OOH of cave nebula

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SH2-155, RGB OOH of cave nebula

Narrowband OOH image comprising ~ 2.5h of HA and 2h of OIII with a 200mm Newtonian at F5.0. Some additional signal and RGB stars from ~ 1h of OSC imaging using a UHC filter. The OIII emission of this region is really very weak in comparison with the HA and rather than stretch it up too far here it is depicted more or less in true proportion to the HA as just a subtle lightening and change in coloration around the bright nebula edge.

Sh2-155 (also designated Caldwell 9) is a diffuse HII region with ongoing star formation about 2400 ly distant and spanning about 35 ly in the constellation Cepheus. The nebula sits within a larger nebula complex - Cep OB3 Association and part of the Cepheus molecular cloud - containing emission, reflection, and dark nebulosity. It has been suggested that radiation from the hot O-type star HD 217086 (bright star at lower centre of the image) is compressing the region, triggering the formation of a new generation of stars - a conclusion supported by the Chandra X-ray Observatory and Spitzer Space Telescope studies which indicate a progression of stellar ages in front of the cloud consistent with the hypothesis of triggered star-formation

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C

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Astrometry.net job	6932640
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SH2-155, RGB OOH of cave nebula

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