ASTR 101 1st Edition Lecture 23 Outline of Last Lecture I. Eclipsing Binary,II. HR-diagramOutline of Current Lecture I. Main sequence stars,II. Stars outside of main sequence,III. Star clustersCurrent Lecture(HR-diagram ctd)I. Main sequence starsa. What is the significance of the main sequence? --these stars are relatively younger than other stars; they're burning hydrogen into helium for nuclear reactions: their cores are very hot. It takes hundreds of thousands of years for the core to emit gamma rays. b. High mass and low mass stars. c. Sun's life expectancy: 10 billion years. II. Stars outside of the main sequence = stars that have consumed all of their hydrogen. a. Most massive stars produce super giants. When the stars stop burning hydrogen, they increase in size and become super giants and their temperature becomes lower (makes sense b/c the core has stopped burning).b. Giants and super giants are far larger than the main-sequence stars and white dwarfs. c. A dead star is always the most stable star-- a dead star will not do much over the next 10 billion years. III. Star clusters:a. 2 types: open (loosely packed group of about 1000 stars) and globular clusters (up to 1 million stars clustered closely together. b. We can measure the age of a star cluster. We assume that all of the stars in a globular cluster are the same age, and then we test that. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a
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