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Sh2-155 - The Cave Nebula in the Hubble Palette

Technical card

Resolution: 4131x3305

Dates: Aug. 12, 2017Aug. 13, 2017

Frames:
Astrodon Ha 5nm: 111x120" (gain: 201.00) -20C bin 1x1
Astrodon OIII 3nm: 325x120" (gain: 201.00) -20C bin 1x1
Astrodon SII 3nm: 132x120" (gain: 201.00) -20C bin 1x1

Integration: 18.9 hours

Darks: ~50

Flats: ~50

Bias: ~250

Avg. Moon age: 19.47 days

Avg. Moon phase: 76.85%

Bortle Dark-Sky Scale: 6.00

Astrometry.net job: 1693706

RA center: 344.391 degrees

DEC center: 62.578 degrees

Pixel scale: 0.648 arcsec/pixel

Orientation: 29.730 degrees

Field radius: 0.476 degrees

Locations: Future World Media Home Observatory, Taylor, MI, Michigan, United States

Description

Had a very hard time pulling OIII out. They don't even list a magnitude for this DSO. Very faint.

Sh2-155 (also designated Sharpless 155 or S155) is a diffuse nebula in the constellation Cepheus, within a larger nebula complex containing emission, reflection, and dark nebulosity. It is widely known as the Cave Nebula, though that name was applied earlier to Ced 201, a different nebula in Cepheus. Sh2-155 is an ionized H II region with ongoing star formation activity, at an estimated distance of 725 parsecs (2400 light-years) from Earth.

Sh2-155 was first noted as a galactic emission nebula in 1959 in the extended second edition of the Sharpless catalogue, being a part of the much larger Cep OB3 Association. Although Sh2-155 is relatively faint for amateur observation, some of its structure may be seen visually through a moderately sized telescope under dark skies.

Sh2-155 lies at the edge of the Cepheus B cloud (part of the Cepheus molecular cloud), and is ionized by young stars from the Cep OB3 association. It has been suggested that radiation from the hot O-type star HD 217086 is compressing the region, triggering the formation of a new generation of stars. A study of the region's young stellar objects by the Chandra X-ray Observatory and Spitzer Space Telescope shows a progression of stellar ages in front of the cloud, supporting the hypothesis of triggered star-formation.

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Author

Douglas J Struble
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Sh2-155 - The Cave Nebula in the Hubble Palette, Douglas J Struble