Sh2-157, as designated in the Sharpless Catalog, is an emission nebula located in the constellation Cassiopeia approximately 8,000 light-years distant. It is only a short distance from the famous Bubble Nebula. The small open cluster of stars located in the upper right of the image is designated NGC 7510 and lies approximately 11,400 light-years away. The small bright nebular object just below the "blue left pincher" is designated Sharpless 157a. It is a nebula surrounding the Wolf Raynet star WR-157.
The image above was compiled from narrow band filtered exposures to create a mapped color depiction of the nebula. The standard Hubble pallet of SII mapped to red, Ha mapped to green, and OIII mapped to blue was utilized for the image. The stars were overlaid with data from a Near True Color (Ha/OIII/OIII) image.
A Near True Color image of Sh2-155 may be viewed here.