The Stars - The Stars The Properties of Stars Distance Luminosity Temperature Mass Parallax d=1/p Only works for nearby stars Brightness Apparent

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The Stars
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The Properties of Stars Distance Luminosity Temperature Mass
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Parallax d=1/p Only works for nearby stars
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Brightness Apparent brightness Absolute brightness – Luminosity Inverse square law
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Stellar Mass To directly determine mass, we need an orbiting object! Binary Star Systems Visual Binary Eclipsing Binary Spectroscopic Binary Let’s see some animations, Jim!
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Temperature Photometry – blackbody spectrum Spectroscopy
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The Spectra of Stars In the 1880’s a system of spectral classes of stars was created based on the appearance of spectral lines. It was a classic early classification scheme…. .they started with A, B, C
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Stellar Classification Like most early classification systems they got it wrong initially Today we arrange spectral classes by temperature Wien’s Law: The hotter the object, the bluer the radiation it emits, and the more total energy is emitted.
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Stellar Classification The hottest stars turned out to be (of course) the bluest. Also the level of heat determined what sorts elements would be prominent in the star’s spectrum For example only the hottest stars can ionize helium Only the coolest stars can have molecules
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Spectral Type Classification System O B A F G K M Oh Be A Fine Girl/Guy, Kiss Me! 50,000 K 3,000 K Temperature (L)
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The Hertzsprung-Russell Diagram Luminosity Spectral bright faint hot cool A very useful diagram for understanding stars We plot two major properties of stars: Temperature (x) vs. Luminosity (y) Stars tend to group into certain areas
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HOT COOL BRIGHT FAINT
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The Main Sequence (MS) 90% of all stars lie on the main sequence! These stars are burning hydrogen.
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How can two stars have the same temperature, but vastly different luminosities? The luminosity of a star depends on 2 things: surface temperature surface area (radius) The stars have different sizes!! The largest stars are in the upper right corner of
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This note was uploaded on 08/06/2011 for the course AST 2002 taught by Professor Britt during the Spring '08 term at University of Central Florida.

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The Stars - The Stars The Properties of Stars Distance Luminosity Temperature Mass Parallax d=1/p Only works for nearby stars Brightness Apparent

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