Earth Science Review

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Earth Science Review

• Stars and Galaxies

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Compare apparent magnitude, absolute magnitude
and luminosity.

• Apparent magnitude is a description of how bright
  the star appears when seen from the Earth the
  lower the number the brighter the object a star
  with an apparent magnitude of -2 is brighter than
  one with an apparent magnitude of 4

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Compare apparent magnitude, absolute magnitude
and luminosity.

• Absolute magnitude describes how bright a star
  would be if all of the stars were the same
  distance from the surface of the Earth

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Compare apparent magnitude, absolute magnitude
and luminosity.

• Luminosity described how much energy per second a
  star is giving off due to its fusion reaction

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Identify relative star temperature by star color.

• Blue stars are the coolest
• White stars are hotter
• Yellow stars are hotter still
• Orange stars are still hotter
• Red stars are the hottest

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SUN, STARS AND GALAXIES
Describe the life cycle of (a) small main
sequence stars like the sun and (b) more massive
stars
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SUN, STARS AND GALAXIES
Interstellar gas and dust particles inside a
nebula will start to collide and stick to each
other As the area becomes bigger, it has more
gravity so it attracts more particles and
becomes even bigger Gravitational forces cause
nebula to shrink and start spinning
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SUN, STARS AND GALAXIES
Spinning nebula will flatten into a disk with
a Large mass in the center called a protostar As
particles inside center collide and pressure
in center increases, temperature in protostar
increases Hydrogen atoms start to collide and
combine together to form helium by nuclear
fusion The central core of the protostar ignites
and releases energy making a star
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SUN, STARS AND GALAXIES
Most of a stars life is spent as a main sequence
star as it continues to fuse hydrogen into
helium The energy from fusion trying to make the
star expand is balances by the force of gravity
trying to make the star shrink so the star is
stable The death of a star begins when it has
used up almost all of the helium in its core and
the helium atoms start to fuse into carbon atoms
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SUN, STARS AND GALAXIES
Fusing of carbon produces so much energy that
the gravity of the star cannot hold the gasses
around the core and the gas envelope starts to
expand forming a red giant star. When all of the
helium is fused into carbon, the star Releases
the rest of its gas to form a planetary Nebula
around the dying star
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SUN, STARS AND GALAXIES
As the core of the star cools, it forms a white
dwarf star that will glow until all the heat is
released One all of the heat is gone, the star
is a black dwarf that releases no heat or
light OR As the white dwarf star cools the
pressure increases and the star explodes as a
nova
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Describe neutron stars, black holes and pulsars.

• A small star will eventually not have enough
  gravity in its core to hold the gas envelope
  around the core once all of the gases have fused
  together
• Once the gases a spread out into space the
  remaining core become a neutron star
• Think of what is left after you burn a match or a
  piece of charcoal

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Describe neutron stars, black holes and pulsars.

• A large star has so much gravity in its core that
  it pulls the gas envelope down onto it
• The pressure of the gases compressed the core
  into a dense but very small piece of matter
• The gas envelope will explode away from the core
  as the pressure increases
• The core has so much gravity that it produces an
  area where even light cannot escape called a
  black hole

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Describe neutron stars, black holes and pulsars.

• A pulsar is a special type of neutron star that
  has produce a high speed rotation as it collapses
• Imagine the leftover core of a small star
  spinning about as fast as a household blender

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Identify the three major types of galaxies by
shape.