NOTES: Spectral Class (Color-Temperature Class):

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NOTES Spectral Class (Color-Temperature
Class) Annie Jump Cannon (1912) classified dark
lines for 200,000 stars! O B A F G K M
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T BLUE RED Subclasses
Sun is a G2V star. A. 1-10 Spectral Subclass. B.
Luminosity Class I-V (I--supergiant, V--main
sequence). The Evolution of a Star Hertzsprung-
Russell Diagram (1910) A plot of Luminosity vs
Surface Temperature, T (see overlay). A one solar
mass star like the sun goes through the stages
of protostar, main sequence, red giant,
planetary nebula, white dwarf.
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Spectral Class (Color-Temperature Class) Annie
Jump Cannon (1912) classified dark lines for
200,000 stars! O B A F G K M Pnemonic Oh Be
A Fine Geek, Kiss Me
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T BLUE RED
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Subclasses Sun is a G2V star. A. 1-10 Spectral
Subclass. B. Luminosity Class I-V
(I--supergiant, V--main sequence).
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Nearby stars can be plotted-- Luminosity vs
Surface Temperature, T
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The more stars we plot, the more we see patterns.
HR Diagram
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The majority of stars lie on the main sequence of
the H-R Diagram where they burn Hydrogen in their
cores.
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Arthur Eddingtons great discovery! Mass
determines stages of star life.
Analogy weigh the baby at birth, and know
everything that will happen to the baby.
He also proved stars bend light Like Einsteins
theory suggests.
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Also he suggested that star pressure balances
gravity.
The outward pressure is created by heat and light.
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The Hertzsprung-Russell, or H-R Diagram allows us
to plot the stages of life of stars from their
initial mass.
Lifetime of a 1 solar mass star
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Multiple Star Systems More than half have
companions. Most are Binaries.
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Optical double--a false binary --two stars not
bound together, one at a greater distance.
Albireo, an optical double. 10/25/03
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Spectroscopic binary We don't see separate
stars, just separate spectra
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Eclipsing binary--one star eclipses another. Two
dips in the light curve.
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Visual binary--actually seen as separate.
Castor in Gemini a visual binary