Topic 3.1 - Constellations

  • Created by: goldstar3
  • Created on: 30-05-18 16:05

A) Stars

  • Point of light in the sky
  • Vary in size, temp and therefore colour
  • Twinkle close to horizon due to turbulent air
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A) Binary Stars

  • 2 or more stars gravitationally linked
  • In the same area of space
  • Can be viewed through telescope
  • Light output as one eclipses the other
  • Doppler shift in spectra
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A) Optical double stars

  • Appear next to each other
  • Millions of kms apart
  • e.g. Alcor and Mizar in the Plough
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A) Constellation

  • Group of stars that appears to make a pattern in the sky
  • Look close but usually far apart
  • May not be gravitationally linked
  • Pattern line of sight effect
  • See different constellations at different times of year
    • Due to Earth's rotation and tilt of axis
  • Appearance may be altered when planet passes in front
  • Official area of sky containing a pattern of stars
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A) Asterism

  • Pattern of stars
  • May (not) be linked to constellation
  • e.g. the Plough, Summer/Winter triangle
  • Fun/popular name for a pattern of stars
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A) Open Cluster

  • Group of stars close to each other in space
  • Bright and relatively young
  • Group of a dozen - 1000 stars
  • Found around galactic plane
  • e.g. Pleiades
  • Faint, fuzzy appearance
  • Blueish in colour
  • A few bright stars visible
  • Patch of many stars

When stating 2 facts, state age & number

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A) Globular cluster

  • Spherical shaped group of stars
  • Dimmer and older
  • Found around galactic nucleus/halo/bulge
  • Usually old red giants/white dwarfs packed tightly
  • 100,000-1,000,000 stars
  • e.g. M13 in hercules

When stating 2 facts, state age & number

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A) Nebula

  • Blurry patch of light in space
  • Where stars are born/dying/have died
  • Not necessarily galaxy, can be an object in our galaxy
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B) Stars within constellations

  • Labelled with Greek alphabet
  • Bayer designation
  •  α, β, γ, ẟ, ε
  • Doesn't take into account variable brightness
  • Sometimes alpha isn't brightest
  • Constellation boundaries have changed
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C) Official list of constellations

  • Original losts in 2000BC by early Babylonian farmers
  • Used stars for calendars and navigation
  • Compendium of constellations: 'The Almagest' by Ptolemy
  • Many based on Greek mythology
  • Constellations added when southern hemisphere explored
  • List formalised by IAU in 1920s to 88
  • Chinese/Indian/Aboriginal had own (names for) constellations 
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