Sh2-155, the Cave Nebula: Sh2-155 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. Sh2-155 is an ionized H II region with ongoing star formation activity, at an estimated distance of 2400 light-years from Earth. 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.

Photographer: Bart Delsaert

Telescope: 16″ f3.75 Dream Scope
Mount: ASA DDM85
Camera: FLI ML16803
Exposure: 185x5min LHaRGB (Ha blended with RGB)