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Chapter 3 Stars and Galaxies
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Section 1:Tools of Astronomy Electromagnetic Spectrum Includes radio waves, infrared radiation, visible light, ultraviolet radiation, x-rays, and gamma rays Ranges from long wavelength to short wavelength
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Visible light : Complementary Colors Blue and Green lights make the color _________
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Visible Light Telescopes Refracting telescope Uses convex lenses to focus on a small area
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Reflecting telescope Built by Issac Newton Uses a mirror instead of lenses
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Radio Telescopes Used to detect radio waves Let’s review !!
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Spectrographs Breaks light from an object into colors and photographs of resulting spectrum Get information about chemical composition and temperatures of stars
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Types of visible Spectrum Continuous - Formed by white light Includes all colors of spectrum (ROY G BIV) Dark-line – white light passes through a cool gas Bright-line (emission) – due to a gas that has been heated.
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Classifying Stars Stars – sphere of glowing gas due to fusion Classify stars by: size, temperature Brightness (magnitude)
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Sizes of Stars Supergiant – Largest – 1000x as big as the sun Giant Medium sized – most stars White dwarf Neutron stars - smallest
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Color and Temp of Stars Hottest – Blue (35,000 C) White Yellow Red-orange Coldest – Red (3000 C)
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The H-R diagram Shows the relationship between surface temperature of a star and brightness
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Lives of Stars Nebula – large amount of gas an dust over a large area Birthplace of stars
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Lifetime of Stars How long a stars lives depends on its size. Stars that have more mass than the sun have shorter lives. Stars that have less mass live longer.
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Death of Stars Once fuel is gone: White dwarf star (when small or medium stars die) A neutron star (form when giant stars die) Black hole – form when massive stars die)
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Black hole
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Constellations Not really a group of stars – just looks that way 88 constellations
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Circumpolar constellations Seen all night long in the northern hemisphere
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Orion
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Ursa Major
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Ursa Minor (little bear)
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Cassiopeia
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Cepheus
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Draco
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Galaxies A giant structure in the universe that contains millions of stars Milky Way the galaxy our sun is in
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Three types of galaxies: Spiral galaxies Center of Milky way is about 25,000 light years away.
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Elliptical Galaxies “flattened balls” Contains old stars Not a lot of gas and dust
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Irregular Galaxies No real shape
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