Megan Garmes

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Stages of Stars

• Megan Garmes
• Betsy Nichols

2
What is a star?

• Stars are hot bodies of glowing gas that start
  their life in Nebulae.
• Career of a star depends mostly on its mass.
• The more massive the star, the more pressure is
  built up inside.
• Stars radiate energy in all directions into
  space, allowing us to unravel the secrets of our
  universe.

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Different Types of Stars

1. Giants D. Supergiants
2. White Dwarfs E. Sun
3. Main Sequence

4
Hertzsrung Russell Diagram
It shows that the temperature coincides with the
luminosity, the hotter the star the higher the
luminosity the star has. You can also tell the
size of each star from the graph as the higher
the radius the higher the temperature and
luminosity.
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Facts about stars

• Vary in size, mass, and temperature
• The color of a star is determined by its
  temperature
• Hottest stars are blue and the coolest are red
• Nuclear fusion in the stars core produces the
  stars energy
• Brightness is measured in magnitude (the brighter
  the star, the lower the magnitude)
• There are two types of magnitude
• Apparent magnitude-brightness seen from Earth
• Absolute magnitude-brightness seen from a
  standard distance of 36.2 light years

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Life of a small star

• Stage 1
• Stars are born in a region of high density
  Nebula, and condenses into a huge globule of gas
  and dust and contracts under its own gravity.
• Stage 2
• A region of condensing matter will begin to heat
  up and start to glow forming Protostars. If a
  protostar contains enough matter the central
  temperature reaches 15 million degrees
  centigrade.
• Stage 3
• At this temperature, nuclear reactions in which
  hydrogen fuses to form helium can start.

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Image of the outflow and protostar
Outflowred Protstargreen
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• Stage 4
• The star begins to release energy, stopping it
  from contracting even more and causes it to
  shine. It is now a Main Sequence Star.
• Stage 5
• A star of one solar mass remains in main sequence
  for about 10 billion years, until all of the
  hydrogen has fused to form helium.
• Stage 6
• The helium core now starts to contract further
  and reactions begin to occur in a shell around
  the core.

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• Stage 7
• The core is hot enough for the helium to fuse to
  form carbon. The outer layers begin to expand,
  cool and shine less brightly. The expanding star
  is now called a Red Giant.
• Stage 8
• The helium core runs out, and the outer layers
  drift of away from the core as a gaseous shell,
  this gas that surrounds the core is called a
  Planetary Nebula.
• Stage 9
• The remaining core ( 80 of the original star) is
  now in its final stages. The core becomes a White
  Dwarf the star eventually cools and dims. When it
  stops shining, the now dead star is called a
  Black Dwarf.

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Red Giant
Is an expanded small star, this happens because
the helium is hot enough to convert into carbon,
and the outer layers of the core begin to expand
and shine less brightly.
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• Life of a massive star (10 solar masses)
• Stage 1
• Massive stars evolve in a similar way to a small
  stars until it reaches its main sequence stage.
  The stars shine steadily until the hydrogen has
  fused to form helium ( it takes billions of years
  in a small star, but only millions in a massive
  star).
• Stage 2
• The massive star then becomes a Red Supergiant
  and starts of with a helium core surrounded by a
  shell of cooling, expanding gas.

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Red Super Giant
Just like in the process of a small star, a
massive star expands into a large mass called a
red super giant
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• Stage 3
• In the next million years a series of nuclear
  reactions occur forming different elements in
  shells around the iron core.
• Stage 4
• The core collapses in less than a second, causing
  an explosion called a Supernova, in which a shock
  wave blows of the outer layers of the star. (The
  actual supernova shines brighter than the entire
  galaxy for a short time).
• The star going into a stage called Supernova and
  contracting to become a neutron star

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Final Stage

• Stage 5
• Sometimes the core survives the explosion. If the
  surviving core is between 1.5 - 3 solar masses it
  contracts to become a a tiny, very dense Neutron
  Star. If the core is much greater than 3 solar
  masses, the core contracts to become a Black
  Hole.

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Sky above 396'6"N 8430'34"W at Mon 2004 Apr 5
1937 UTC Explain symbols in the map.
                                                  
                                                  
                                                  
                                          
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Burnout and Death of Stars
Death of Low Mass Stars gtMay remain on main
sequence for up to 100 billion years gtNever
evolve to become bloated red giants gtRemain as
stable main sequence stars until they consume
their hydrogen fuel and collapse into white
dwarfs Death of Massive Stars gtHave relatively
short life spans gtTerminate in an explosion
known as a supernova gtDuring this event, a star
becomes millions of times brighter when it
consumes most of its nuclear fuel gtPredictions
say that stars condense into very hot bodies
known as neutron stars
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• White Dwarfs
• -Extremely small stars with densities greater
  than any known terrestrial material

Remnants of Stars

• Neutron Stars
• -remnants thought to be of supernova events

• Black Holes
• -massive star that has collapsed to such a small
  volume that its gravity prevents the escape of
  all radiation