Star Groups

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Star Groups

• Galaxies, Nebulae, and
• Star Clusters

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Galaxies

• a large group of billions of stars in space
• three types of galaxies elliptical, spiral,
  and irregular.

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Irregular Galaxies

• No orderly shape
• New or baby galaxies
• A lot of dust and gases

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Large and Small Magellanic Clouds
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A Close up of the Large Magellanic Cloud
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Zwicky 18
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The Irregular Galaxy Sextans -A
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Spiral Galaxies

• thick center of stars with arms that spiral
  from the center
• spiral galaxies are middle age galaxies.

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Whirlpool Galaxy (M51)
Notice the concentration of stars near the center
and the arms radiating out from it.
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Andromeda Galaxy (M31)
The Andromeda galaxy is the closest galaxy to our
Milky Way Galaxy. It is 2.2 million light years
from the Milky Way galaxy. It can be seen with
the naked eye.
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Andromeda Galaxy
A light year is the distance that light travels
in one year. Andromeda is 2.2 million light
years from the Milky Way. Therefore, it takes
the light for Andromeda that you see 2.2 million
years to reach you.
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The Pinwheel Galaxy (M33) is a young spiral
galaxy. It does not yet have clearly defined
arms.
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The Sombrero Galaxy (M104)
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M 99 Spiral Galaxy
Triangulium Galaxy
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Elliptical Galaxies

• Round or flat discs
• Very little dust and gases
• Older galaxies

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M32
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M 87
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M 59
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Other Galaxy Photos
The following photos contain several types of
galaxies.
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M82 (The Cigar Galaxy) (irregular galaxy) and M81
(spiral galaxy) The M and number found with
space objects stands for Messier object after
Charles Messier who catalogued them.
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The Markian Chain Galaxy Group
All of the stars that you see behind this chain
of galaxies are actually other galaxies. Stars
are contained INSIDE galaxies, not randomly in
space.
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Leo Trio Galaxy Group
(M65, M66, and NGC3628)
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Hubble Deep Space Images
This picture was taken by the Hubble telescope
and shows galaxies on the outer limits of the
universe.
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So. What type of galaxy do we live in ???
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So. What type of galaxy do we live in ???
SPIRAL
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The Milky Way Galaxy
Since we cannot travel outside our galaxy, this
photo was taken from inside the Milky Way looking
towards the center. The Milky Way received its
name from the milky appearance that it has in
the night sky.
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The Milky Way contains 100-200 billion stars plus
dust and gases. All of the stars that we see
with the naked eye are in the Milky Way Galaxy.
The Milky Way is 100,000 light years in
diameter and 15,000 light years thick.
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From the top, our galaxy may look something like
this. We are located in one of the outer arms
of the galaxy, called the Orion Arm. We would be
located somewhere near the x on this drawing.
Our solar system is about 25,000 light years
from the center of the galaxy.
X
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Our Milky Way Galaxy is a spiral galaxy.
This is how our galaxy probably looks from
the side.
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Nebulae

• areas of dust and gases in galaxies
• usually leftovers of a supernova
• birthplace of new stars

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Crab Nebula (M1) (supernova remnants)
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Horsehead Nebula which is found in the
constellation Orion
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The horsehead nebula is named for the huge plume
of dust and gases that resembles a horses head.
The plume is thought to be a nursery for
protostars (new stars). This nebula is found
near the belt stars in the constellation Orion.
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This is a picture of the constellation, Orion.
The horsehead nebula is seen (with a telescope)
near the three belt stars of this constellation.
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The Ring Nebula (M57)
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Dumbbell Nebula (M27)
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The Owl Nebula (M97) and a spiral galaxy
(M108) (The spiral galaxy is at the top right of
the photo while the Owl nebula is at the lower
left.)
Close up of the owl nebula.
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Other Nebulae
Omega Nebula
Trifid Nebula
Orion Nebula
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Dumbbell Nebula
Lagoon Nebula
DeMairans Nebula
Ring Nebula
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Star Clusters
A star cluster is a group of stars that is
smaller than a galaxy (usually hundreds of
stars). Star clusters are found within
galaxies. Two types of clusters open and globular
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Pleiades (M45)
Pleiades is an open cluster. Open clusters are
large, loosely organized groups of hundreds of
stars.
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M50
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M36
Butterfly Cluster
More Open Clusters
Ptolomy Cluster
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M4 Cluster
M4 is a globular cluster.
A globular cluster is a group of hundreds or
thousands of stars in a spherical shape.
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Hercules Cluster
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Double Cluster
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More
M54
M80
Globular Clusters
M72