Nebula

There are a large number of types of nebula, each vastly different from one to another. These types of nebula all have their own speciality in regard to the way they were formed and how they fit their purpose as nebula. The names of these types of nebula are; H-II regions, planetary nebula, supernova remnants and diffuse nebula.

An H-II region is a region of partially ionised gas. What also distinguishes H-II region from the others is that it contains vast amounts of ionised hydrogen, meaning it consists of many free protons. H-II regions are areas where many large blue stars are formed. These blue stars would form inside a large cloud of hydrogen gas, giving off great amounts of ultraviolet light. This ultraviolet light then ionises the surrounding gas. The reason why they give off such enormous amounts of ultraviolet is because of their short life span. H-II regions can be several hundred
These objects behind it may be stars or other types of nebulae. The reason why the light is blocked out is because dark nebulae contains a very high concentration of this interstellar dust. Due to the high concentration it allows the dust to scatter and absorb all incident light. Dark nebula is most visible when in front of a very bright star as it allows the observer to see the nebula as a silhouette. The average temperature inside dark nebulae ranges within 1-100 kelvin. This temperature allows star formation to take place. Dark nebula are formed in very irregular shapes but the most common can be said to follow a serpentine type shape. Dark nebulae vastly ranges in size, The smallest observed being three light years across to the biggest being over 200 parsecs across. An example of a well known dark nebula is, As seen in figure 9, Barnard 33 (Horse head nebula). Barnard 33 is located in the constellation