lecture_tan20 - Key Concepts: Lecture 20: Measuring the...

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Measuring the properties of stars The Hertzsprung-Russell (HR) Diagram (L versus T) The Stefan-Boltzmann Law: flux emitted by a black body = ! T 4 Binary Stars: used to measure stellar mass The Hertzprung-Russell Diagram In an attempt to understand the physical nature of the stars, astronomers tried to find correlations between their observed properties – Temperature or Spectral Class – Luminosity The American Henry Norris Russell (1913) and the Danish engineer Ejnar Hertzsprung (1911) independently made a diagram showing these stellar properties. Stars group themselves in various parts of the diagram. The Hertzprung-Russell Diagram • Hertzprung and Russell found – Stars did not occur with all possible combination of temperature and luminosity – Stars tended to group together – A large number of stars (including the sun) were found in a band they called the Main Sequence This suggested that the observed properties of stars are interrelated Luminosity Hot Cool Question
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This note was uploaded on 09/07/2011 for the course AST 1002 taught by Professor Dr.haywoodsmith,jr during the Spring '07 term at University of Florida.

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lecture_tan20 - Key Concepts: Lecture 20: Measuring the...

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