The Nature of the Stars
Guiding Questions
Parallax
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Careful measurements of the parallaxes of stars reveal their distances
Barnard’s star has a parallax of 0.54 arcsec
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If a star’s distance is known, its luminosity can be determined from its brightness
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The Population of Stars
Stellar Motions
Astronomers often use the magnitude scale to denote brightness
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A star’s color depends on its surface temperature
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Photometry and Color Ratios
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The spectra of stars reveal their chemical compositions as well as surface temperatures
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Relationship between a star’s luminosity, radius, and surface temperature
Finding Key Properties of Nearby Stars
Hertzsprung-Russell (H-R) diagrams reveal the different kinds of stars
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Spectroscopic Parallax
A Binary Star System
Binary Stars
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Binary star systems provide crucial information about stellar masses
Mass-Luminosity Relation for Main-Sequence Stars
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Spectroscopy makes it possible to study binary systems in which the two stars are close together
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Light curves of eclipsing binaries provide detailed information about the two stars
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Key Words
Author: Michael Cohen
E-mail: mrcohe@ship.edu
Homepage: http://physics.ship.edu/~mrc/