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E3N6_Oct27[1] - and Scatter Horsepower vs Weight The H-R...

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Observable Properties of the Stars 1) Luminosity 1. Brightness + distance 2) Effective Temperature - Color maximum wavelength - Spectral lines 3) Radius L + T + S.B. Law => Radius Eclipsing Binaries 4) Mass -binaries 5) Composition -spectra
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Getting masses from binaries
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Light curve of an eclipsing binary
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Edge on eclipsing binary
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Number vs. Luminosity
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Number nearby as a funciton of luminosity
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Mass—Luminosity Relation
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Connections between properties Relation between mass and lifetime – From observed Mass-Luminosity relation: Luminosity is proportional to Mass (to the 3.5 power) – Lifetime is just fuel supply (proportional to Mass) divided by the rate of consumption (Luminosity—related to Mass from observed relation), so lifetime is inversely proportional to mass (to the 2.5 power) Fundamental relations ? – Do related properties exist, and what can we learn from them?
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An Example of Connections
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Unformatted text preview: and Scatter Horsepower vs. Weight The H-R Diagram • Plotting each one of the observables for stars against each of the others, and searching for something showing a relation (not a scatter diagram), Hertzsprung and Russell independently discovered the most important of these, what we now call the H-R diagram in their honor. It is usually plotted (by theorists) as Luminosity vs. Temperature (with the temperature increasing to the left by an awkward historical convention) Spectral Class vs Absolute Magnitude Radius vs. Mass Number vs. Mass Schematic H-R Diagram Bright Stars stars labelled Biased Samples • What is sample bias ? – Can you give some examples from media polls? • Two principal kinds of sample bias in H-R diagram – Brightness limited sample : over-represents intrinsically bright (luminous) stars – Proper motion sample : under-represents bright and rare stars Sample Bias...
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