ASTR 111 Chapter Notes -Galactic Coordinate System, Celestial Equator, Cosmogony
Document Summary
Classical cepheids are also known as cepheid i stars and w virginis cepheids are known as. Each of these stars has a xed period of oscillation. All cepheid i stars have a period of 1 to 100 day. Cepheid i variables (classical)- these are very large bright yellow stars (supergiants). They have absolute magnitudes in the range 1. 5 to 5, With each star"s magnitude varying 0. 1 to 2 magnitudes. They are extremely rare (~600 in galaxy) and are found only in the spiral arms. Cepheid ii variables (w. virginis)- these are bluer than cepheid i stars and have different ligh tcurves. Their periods lie in the range of 3 to 50 days. Absolute magnitudes in the range 0. 5 to 4 a few dozen are known. Globular clusters- these are symmetric clusters of hundreds of thousands of stars scattered spherically, uniformly about the galaxy. The stars are different than spiral arm stars since they have a very low metal content.
