References

Online Mark Krumholz’s Astro 230 Lecture Notes Harvard Ay201b Online Textbook Barbara Ryden’s Ast 825 Lecture Notes Stephen Portillo’s Nebula Predictor - For understanding images of HII regions Books Draine, Bruce - Physics of the Interstellar and Intergalactic Medium: Ch. 37 Osterbrock, Donald & Gary Ferland - Astrophysics of Gaseous Nebulae and AGN Shu, Frank - The Physics of Astrophysics: Gas Dynamics: Ch. 20 http://www.ucolick.org/~krumholz/courses/spring12_ast230http://ay201b.wordpress.com/2011/04/12/course-notes/#expansion_of_hii_regionshttp://www.astronomy.ohio-state.edu/~ryden/ast825/ch5-6.pdfhttp://portillo.ca/nebula/shapeimage_2_link_0shapeimage_2_link_1shapeimage_2_link_2shapeimage_2_link_3

For more information on ionization fronts and HII regions, consult these references