Astronomy 2021A/B Lecture Notes - Lecture 11: Annie Jump Cannon, Planetary Nebula, Upsilon Andromedae
9 Dec 2016
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Document Summary
Modern definition of a star is a large ball of gas that generates energy by nuclear fusion in its hot central core. 90% of life of a star is fusing 4h into 1h. When its begins to exhaust its core, it begins to grow larger and brighter, becoming a giant or a supergiant star. Grows so large and luminous because during the time that central core fuses hydrogen, the energy generation helps the core resist the crush of gravity and maintain its size. You can still orbit a dead star but you probs wont find life. Different stars will have different qualities, impacts habitability around those stars. Differ in properties, such as mass, temperature, light output and composition. An extremely luminous star that is far away may look dim, while a modestly luminious star that is close may shine quite brightly. Each type is also subdivided and subclassified by each type by number, example g could be subclassified as g0,g1,g2----g9.
