Here I return to a subject that I had already shot in HOO at the beginning of my "career" as an astrophotographer. It's nice to come back to a subject that you already know every now and then, because you have a better connection and familiarity with it.
This is an area of intense stellar formation showing many interesting details, as for instance the HH168 area (the red island at bottom-center of the image). The overall ionization is due mostly by the star HD 217086 (top-center, highlighted in the annotated version) that is blowing the whole area and shaping it in its peculiar way.

Sh2-155
Also called LBN529 Caldwell9
Galactical Coordinates: (110.15°, 2.61°)

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, 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 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 HD217086 (identified in the annotated version) 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.

The name "Cave Nebula" was coined for this object by Patrick Moore, presumably derived from photographic images showing a curved arc of emission nebulosity corresponding to a cave mouth. The name's application to Sh2-155 has come into vogue through the nebula's inclusion in Moore's Caldwell catalogue as object Caldwell 9. Please note that SIMBAD lists the name for Ced 201, but not for Sh2-155.

VdB155
Designates the Herbig Ae/Be Star HD216629. A Herbig Ae/Be star (HAeBe) is a pre-main-sequence star: a young (<10 Myr) star of spectral types A or B. These stars are still embedded in gas-dust envelopes and are sometimes accompanied by circumstellar disks. Hydrogen and calcium emission lines are observed in their spectra. They are 2-8 Solar mass (M☉) objects, still existing in the star formation (gravitational contraction) stage and approaching the main sequence (i.e. they are not burning hydrogen in their center).

The HH168 area
I have not found a collective designation for the evident reddish star formation area close to the bottom of the image. It hosts a quantity of young stellar objects and Herbig-Haro 168 A, B, C, etc.

(info excerpted from Wikipedia and Simbad)