Sh2-199 - The Soul Nebula

Sharpless 2-199, LBN 667 or the Soul Nebula is an emission nebula located in the constellation of Cassiopeia. It is a bright spherical HII region which is ionized by by several small open cluster that are embedded in the nebula: CR 34, 632, and 634. The object is also commonly named by the cluster designation IC 1848. It is surrounded by several smaller emission nebula adjacent to the main region, they are also including multiple dark dust lanes of cold molecular gas.

The nebula contains a large extended radio source in its center, called Westerhout 5 (W5). A cluster of extremely luminous O stars emits strong UV-radiation that ionizes the molecular gas and clears its environment of dust, thus creating large "bubblelike" cavities. Areas that are already dense can shield the radiation and get compressed by the strong stellar winds, which can trigger new star formation on its own. This process creates the pillar structures pointing towards the stars that creating them. In some structures hints of ongoing early star formation can be observed. A nice video explaining the above described processes can be found here.

Photographed from Bamberg, Germany under Bortle 5 conditions.