Download How are galaxies classified

Q: How are galaxies classified?
A: By their shape.
Q: What tool has helped astronomers
understand a lot about galaxies?
A: The Hubble Space Telescope
Q: Name three characteristics of spiral
galaxies.
 Have a bulge at the center
 Have spiral arms
 Arms made up of gas, dust, and new
stars
 Examples: Andromeda and our
Milky Way Galaxy
Q: Name two characteristics of barred
galaxies.
 Much like spiral galaxies
 Have two distinct “bars” vs. many
spiral arms
Q: Name three characteristics of elliptical
galaxies.
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Q: Name two characteristics of lenticular
galaxies.
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Q: What kind of star cluster is a group of
older stars, looks like a ball, and contains
up to one million stars?
About 1/3rd of all galaxies
Simply a massive blob of stars
Spherical or more stretched out
Very bright centers with little extra
gas and dust
 Contain mostly old stars
Has both a bulge and a disk
All the stars are thought to be old
Have no spiral arms
There is little or no gas
A: Globular Cluster
Q: Name three characteristics of irregular
galaxies.
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Q: Galaxies are composed of what four
things?
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Don’t tend to fit into any other class
Irregular shape
No center bulge
May have been formed by the
collision of two or more galaxies
 Many are close in proximity to large
spiral galaxies. Perhaps the spiral
galaxies are distorting the shape of
irregular galaxies.
Billions of stars
Some planetary systems
Gas clouds
Star clusters
Q: What is a large cloud of dust and gas in
interstellar space where stars are born or
where stars explode at the end of their
lives?
A: A nebula
Q: What kind of star cluster is a group of
stars that are close together relative to
surrounding stars? Example: The Pleiades
A: Open Star Cluster
Q: What is star-like, very luminous,
generates a lot of energy, and is very far
away (6 billion light years)
A: A quasar
Q: Which is closest to Earth?
1) the moon
2) the sun
3) other planets in our Solar System
A: The moon
Q: Distances are so great in space that a
new unit was created. What is it called and
how long is this unit?
A: The Light Year
6 Trillion miles/year
Q: How fast does light travel?
A: 186,000 miles/sec
Q: What is the closest star to Earth other
than the sun?
A: The closest star to Earth (other than our
sun) is Proxima Centauri; it is 4.3 light
years (26 trillion miles) away
Q: What is the closest star to Earth other
than the sun that we can see from the
northern hemisphere?
 From Ohio, we cannot see Proxima
Centauri. It can only be seen from
the southern hemisphere.
 The brightest star in the northern
hemisphere (other than our sun) is
Sirius.
 Sirius is referred to as the “dog star”
because it is in the constellation
Canis Major (big dog).
 It is 8.6 light years away from Earth.
Q: “Star A” and “Star B” are the same size,
brightness, and distance from Earth.
A: They will appear to be the same
brightness
When looking at these stars from Earth,
which star will appear to be brighter?
Q: “Star A” and “Star B” are the same size
and brightness. “Star A”, however, is much
farther away from Earth than “Star B”.
A: “Star B” will appear brighter just
because it is closer to Earth.
When looking at these stars from Earth,
which star will appear to be brighter?
Q: True or False?
Stars undergo a life cycle.
A: True
Q: True or False?
The stages of the life of a star generally
follow a pattern and are fairly regular.
A: True
Q: “Star C” is very big and bright.
“Star D” is not so big or bright.
A: “Star C” is much farther away from
Earth, thus, it seems as though it is the
same brightness, or magnitude, as
“Star D”.
How could these two very different stars
seem to be the same brightness from Earth?
Q: Fill in the blank:
 Stars begin their lives as clouds of
dust and gas called ___________.
Q: What does the following describe?
 Gives off no visible light
 Must undergo many changes before
it is recognized as a star.
 It continues to contracts over a
period of millions of years
 Shrinkage causes an increase in
pressure and temperature
Q: What is nuclear fusion?
A: Nebula
A: A protostar
 Hydrogen + Hydrogen = Helium + a
lot of energy!
Q: A star spends most of its life as a
_______, which is a stable condition.
A: Main sequence star
Q: Fill in the blanks:
Very _____ stars burn their fuel much
______ than smaller stars. Their main
sequence may last only a few hundred
thousand years.
A: Large, faster
Q: Fill in the blanks:
________ stars will live on for billions of
years because they burn their fuel much
more ________ than large stars.
A: Small, slowly
Q: Fill in the blanks:
At the end of an average star’s life, it will
expand into what is known as a _______.
Massive stars will become ______ at the
end of their lives.
A: red giant, red supergiants
Q: Fill in the blanks:
Most average stars will blow away their
outer atmospheres to form a ________.
Their cores remain behind and burn as a
______ until they cool down. What is left
is a dark ball of matter known as a ______.
A: Planetary nebula, white dwarf, black
dwarf
Q: What is a supernova?
Q: How long does a supernova shine?
Q: How bright is a supernova?
A: If the star is massive enough, the
collapse of the star will trigger a violent
explosion known as a supernova.
A: Supernovas are very bright and can
cause a brief (few months) burst of
radiation that can outshine an entire galaxy.
A: During this explosion, a supernova can
give off as much energy as our Sun could
emit over its life span!
Q: At the end of their lives depending upon
how large they were to begin with, massive
stars will either become a ____ or a _____.
A: Neutron star or a black hole
Q: List the life stages, in order, of an
average star. (Hint: There are seven
stages.)
A: Stellar nebula, protostar, main sequence
star, red giant, planetary nebula, white
dwarf, black dwarf
Q: List the life stages, in order, of a
massive star. (Hint: There are six stages.)
A: Stellar nebula, protostar, massive star,
red supergiant, super nova, neutron star or
a black hole
Q: What does the color of a star depend
on?
A: Temperature
Q: What can a scientist learn about a star
from its spectrum?
A: Its composition (what it is made of) and
its temperature
Q: What color are the hottest stars? Red,
yellow, orange, green, purple, or blue?
A: Blue
Q:The H-R diagram shows the relationship
of a star’s _____ and its _____.
A: Surface temperature and absolute
magnitude
Q; Name five types of galaxies.
A: Spiral, barred, elliptical, lenticular, and
irregular
Q: Where are globular clusters found?
A: In the spherical halo of spiral galaxies
and near elliptical galaxies
Q: Where are open star clusters found?
A: Along the spiral disk of galaxies
Q: Why do scientists study galaxies?
A: To learn what early galaxies looked
like, and to learn how our galaxy was
formed
Q: What does a star’s color indicate?
A: Its temperature
Q: What kind of galaxy is the Milky Way
galaxy?
A: Probably a spiral galaxy
Q: Which is the largest, a galaxy, a neutron
star, or a nebula?
A: A galaxy
Q: Which of the following magnitudes
indicates the brightest star? 5, -10, or 0
A: -10
Q: What kind of star sends out rapid beams
of radiation? They spin very quickly.
A: pulsars