Stars

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Author:
pricera
ID:
50542
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Stars
Updated:
2010-11-22 20:32:10
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Stars
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Astro Exam 2
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  1. What is a wave?
    a wave traveling disturbace that moves energy without moving mass
  2. What is frequency?
    Number of times wave repeats its self per second.
  3. Visible Light
    1. 400 nm to 700 nm
  4. Dopple Shift
    Oncoming is shorter, outgoing is longer
  5. Radial velocity 2
    Wave goes towards person blue shifted and shorter. Wave goes away longer and red shifted.
  6. Spectrum
    All waves length that are present and how much are present at each wave length.
  7. Atmosphere and light 3
    1.More likely to scatter shorter wave lengths.

    2.Blue light will scatter 60x more than red light.

    3.Person behind equals unscatter, People below equals scatter.
  8. Black Body Radiation 3
    • 1.All marco objects omit this
    • 2.Depends on temp, energy emitted at wave lengths
    • 3.Temp goes up more light is emitted at shorter wave lengths.
  9. Luminosity
    Total energy emitted.
  10. Two things that tell how much energy is emitted from an object.
    Temp and area.
  11. Absorbion Spectrum
    Absorbs gas at particular wave lengths
  12. Emission Spectrum when we heat gas.
    True.
  13. How would a spinning star look? 3
    • 1.Broading effect.
    • 2.Light towards you would be blue shifted.
    • 3.Blurred broading wave.
  14. Thermonuclear Energy Core
    Has nuclear fusion going on helium adam changed to hydrogen adams.
  15. Aparent Magnitude 3
    • 1.Size of the star.
    • 2.Classified stars into six brightness classes.
    • 3.Each step 2.5 brightness coming to your eyes.
  16. Apparent properties do not depend distance and intrinsic properties depend on distance.

    True or False
    False
  17. Apparent magnitude a star would have at a distance of 33 lyrs.

    True or False
    True
  18. Spectral Sequence
    O, B, A, F, G, K, M
  19. Temperature scale that measures like stars. Hottest starting with O and getting cooler as you go down. 7 classes.
    Spectral Sequence
  20. How to find Luminosity?
    L=(alpha)Area x temperature to the fourth
  21. Hertsprung and Russel found that 90% of stars are main sequence.
    True or false
    true
  22. Find luminosity from H-R diagram
    • Luminosity=Brightness
    • (4)(pie)(distance squared)
  23. 7 properties of a star
    • 1. surface area
    • 2. distance stellar parallax
    • 3. temperature spectral type
    • 4. luminosity absolute magnitude
    • 5. chemical composition
    • 6. brightness
    • 7. radial veolcity
  24. What star properties 2 are not instrustic and which one is?
    • Brightness and distance
    • Mass is.
  25. Binary Stars
    • 1. Tell us mass.
    • 2. Pair of stars that orbit each other.
    • 3. gravitionally bound together
  26. Visual binary stars
    Same direction but very long distance apart and are not bound
  27. Thermnuclear fusion
    2 nuclei form 1 nucleus and create lots of energy. This needs high temperature, high density, and high speed to happen.
  28. Interstellar medium
    • 1. 10% of observed mass of galaxy
    • 2. very low dense
    • 3. mostly hydrogen
  29. Bokgloubue
    dark dense regions where stars are formed
  30. protostars
    beginning of a star's life
  31. Length of time star spends on main sequence.
    main sequence lifetime ( high mass stars spend less time.)
  32. Stages a star takes to become giant. 4
    • 1. Helium core shutdown
    • 2. rapid collaspe hydrogen fusion
    • 3. heat from envelope expands and cools
    • 4. core collapses until heluim gets dense enough and hot enough to fuse
  33. Helium flash
    less than 2 solar masses that lets fusion reaction runaway and very exotic
  34. Turnoff point tells age of star

    True or false
    True
  35. Spectroscopic parallax
    Method of determing a star's distance from Earth by measuring its surface temperature, luminosity, and apparent magnitude.
  36. Brown dwarf
    Planetlike bodies with less than 0.08 solar massthat cannot sustain fusion in their cores.
  37. red dwarf
    low mass main sequence star
  38. Stellar Evolution
    • Stellar evolution is the sequence of changes in the
    • characteristics of a star resulting from the physical processes occurring
    • within it. It is the physical “life history” of a star
  39. Why is stellar evolution difficult to study? 2
    1. Stars may exist for billions of years (e.g. Sun is about 4.5 x 109 years old).

    • 2. Humans live for less than 102 years. Meaning
    • that humans can observe less than 1/107
    • (1 10 millionth) of a star like the Sun’s life.
  40. 3 types of spectra
    1. Continuous Spectrum - light like the rainbow

    2. Absorption Line Spectrum - dark lines on a continuous spectrum

    3. Emission Line Spectrum - mostly dark, no continuity
  41. How can spectrum of light tell a star's chemical compostion?
    each element produces its own pattern of spectra lines and with a spectrograph you can see the lines.

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