AST 111 Lecture Notes - Lecture 15: Compact Star, Density Wave Theory, Galactic Center

• School: Tunxis Community College
• Department: Astronomy
• Course: AST 111
• Professor: Reynolds

Document Summary

Hot, massive stars and ionization nebulae are found only near clouds that are actively forming stars. Ionization nebulae appear predominantly red in colour. Reflection nebulae appear predominantly blue in colour. Spiral arms are full of newly forming stars: Home to numerous clusters of young, bright blue stars surrounded by ionization. Spiral pattern of star formation is caused by disturbances called spiral density waves: nebulae. Spiral density wave moves through the disk, The changing gravitational forces among stars in the wave alternately cause stars. Doesn"t affect stars, because they are far apart. However: packs gas clouds closer together, triggering star formation and gas clouds to pack more densely together and then move farther apart. Spiral arms are waves of star formation that spread throughout our galaxy"s disk. Halo stars are all old with a very low proportion of heavy elements, while disk stars come in all ages and contain a higher proportion of heavy elements.