Transcript Galaxy Far Far Away ppt

A Long Time Ago in a
Galaxy Far, Far Away…
The Milky Way Galaxy:
Home Sweet Home!!
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Our home Galaxy is called the MILKY WAY (like
the candy bar )
So named because early stargazers thought the
stars looked like milk spilled across the sky.
YOU ARE HERE…
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The Sun is located on the Orion Arm of the Milky Way
If you look toward the constellation Sagitarius, you are looking
toward the center of the galaxy.
~10,000 parsecs from the center of the galaxy.
How huge is the Milky Way?
“If there’s a bright center to the galaxy, you’re on the planet that
it’s farthest from. “
~Luke Skywalker, Star Wars
SUN
3,300 LY
33,000 LY
75,000 LY
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Milky Way Dimensions:
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75,000 light years from end to end
3,300 light years thick
~33,000 light years from the center of the galaxy to
the Sun
Mass: 4 x 1011 Solar Masses
Galactic
Anatomy
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NUCLEUS: Bright Center
of the galaxy.
NUCLEAR BULGE:
Flattened cloud about 3 pc
in radius around center of
the galaxy.
HALO: Area surrounding
galaxy that contains some
scattered globular clusters.
DISK: Contains most of the
stars in the galaxy.
Jump to Hyperspace?
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By looking at the
radial velocities of
surrounding stars, we
can estimate the
Sun’s velocity to be
about 220 km/s.
It takes about 240
million years for the
Sun to orbit the center
of the galaxy!
Like Spinning a
Pizza…
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Clouds of hydrogen and helium
from the Big Bang
Star motion within causes it to
rotate and contract
Cloud begins to flatten into a
disk
Older stars are left behind in
the halo
The galaxy is now nearly flat
Spiral Arms
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Home to hot bright stars
(O and B)
Used to trace the path of
our spiral arms
Star formation is
continuously renewed in
spiral arms
Journey to the Center
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Nucleus is the most
mysterious part
Evidence of a
Supermassive Black Hole
in Saggitarius:
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High Intensity Radio
Source
Orbits of surrounding
objects
Huge Mass (2.6 million
solar masses)
Small size (3 pc)
Event Horizon is smaller
than a period!
Too massive to be the
remains of a star: possibly
formed when galaxy did
Hubble Deep Field:
Elliptical Galaxies
Spheres or Ellipses
Spiral Galaxies
Barred Spirals
Irregular Galaxies
Galactic Hugeness and Other
Amazing Stuff
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Mega parsec = 3.26
million light years!
Estimate distance using
indicators (clusters,
Cepheids, supernovae)
Dark Matter: Measured
mass is much larger than
predicted mass,
Gravitational lensing
Massive Black Holes:
evidence in orbits of stars
in the center
When Galaxies
Collide…
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Formation of
spiral arms
Distortion or
tearing
Galactic
Cannibalism
Firestorms of Star
Formation
Galactic Mergers
High Speed
Collisions
Local Group:
Our Galaxy’s Neighbors
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The Milky Way is one of about 35 galaxies
that are clumped close together. This
clump is called the LOCAL GROUP.
Milky Way Galaxy
M31: Andromeda Galaxy
Small Magellanic Cloud
M33: Triangulum Galaxy
Large Magellanic Cloud