Celestial hemisphere:  Northern  ·  Constellation: Cepheus (Cep)  ·  Contains:  LBN 527  ·  LBN 529  ·  LDN 1218  ·  Sh2-155
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Sh2-155, Cave Nebula Cephei, Mau_Bard
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Sh2-155, Cave Nebula Cephei

Getting plate-solving status, please wait...
Sh2-155, Cave Nebula Cephei, Mau_Bard
Powered byPixInsight

Sh2-155, Cave Nebula Cephei

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Description

I published a new better SHO version of this object here.

Image taken during 4 nights in September 2021, with my OSC camera and a dual band H-alfa and O-III filter, from Bortle 7 backyard.
I tried this time to apply the H-alpha channel as luminance to the RGB image, and this improved significantly the overall contrast. I experimented various combinations HOO, HHO and intermediate ones, but at the end I liked more the original RGB channels, and stayed with them.

Here follows a compilation  about Sh2-155 from various sources (mostly Wikipedia).

Sh2-155 (also designated Caldwell 9, 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.

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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