EDWARD'S LECTURE NOTES:
More notes at http://tanguay.info/learntracker
C O U R S E
In the Night Sky: Orion
Andrew Norton, The Open University
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C O U R S E L E C T U R E Seven Stars and a Nebula Notes taken on January 6, 2016 by Edward Tanguay |
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Orion
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in south east part of sky
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three stars in a line
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his belt
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two stars below are his feet
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two stars above are his shoulders
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Orion nebula
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a diffuse nebula situated in the Milky Way
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visible to the naked eye
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the closest region of massive star formation to Earth
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24 light years across
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regions of red and of blue-violet
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Greek mythology
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Orion was a hunter
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he first appears as a great hunter in Homer's epic the Odyssey, where Odysseus sees his shade in the underworld
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Artemis was tricked by her brother Apollo and killed her friend Orion
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she asked Zeus to put him up in the stars
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Orion's stars
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shoulders
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Betelgeuse
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red supergiant
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second-brightest in the constellation of Orion
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ninth-brightest star in the sky
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Bellatrix
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third brightest star in the constellation Orion
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27th brightest star
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a massive star with about 8.4 times the Sun's mass.
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20 million years
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old enough for a star of this mass to consume the hydrogen at its core and begin to evolve away from the main sequence into a giant star
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stars live different lengths of time, depending on how big they are
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a star like our sun lives for about 10 billion years, while a star which weighs 20 times as much lives only 10 million years
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belt
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Alnitak
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multiple star
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primary star is a hot blue supergiant
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reported to be a double star by amateur German astronomer George K. Kunowsky in 1819
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Alnilam
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a large blue supergiant star some 1,340 light years distant
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275,000 to 537,000 times as luminous as the Sun, and around 34 times as massive
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the middle star
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Mintaka
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1,200 light years distant
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one of the brightest stars in the sky
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feet
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Saiph
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star at the south-eastern corner
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a bright supergiant star that has exhausted the supply of hydrogen at its core
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Rigel
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the brightest star in the constellation Orion
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the seventh brightest star in the night sky
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actually a triple star system
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Rigel A: a blue-white supergiant
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it has exhausted its core hydrogen and swollen out to 79 times the Sun's radius
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Rigel B: a spectroscopic binary system, consisting of two main sequence blue-white stars of spectral type B9V that are themselves estimated to be 2.5 and 1.9 times as massive as the Sun