UNIT 11
CHARACTERISTICS OF THE UNIVERSE
Lesson 1
Classifying Stars
WARM UP
• Are all stars the same size?
• No
• Are all stars the same temperature?
• No
• Are all stars the same age?
• No
TEST REVIEW
•
Each question is worth 10 points
GALAXIES AND STAR CARDS
• Organize the cards into groups that make
sense to you.
• Be prepared to justify your answer
• You have 5 minutes
GALAXIES AND STAR CARDS
• Justify your answer
• Table 1
• Table 5
• Table 6
• Table 4
• Table 2
• Table 3
GALAXIES
•
Using the computers, you are going to research a type of galaxy.
•
Your letter represents:
• A- irregular galaxies
• Sit at tables 1 and 2
• B- elliptical galaxies
• Sit at tables 3 and 4
• C- spiral galaxies
• Sit at tables 5 and 6
•
You have 10 minutes to conduct your research
•
You will be sharing this information with your peers.
•
Make sure it is quality work and you use scholarly websites.
GALAXIES
• Make GROUPS
• Each group must have an A, B, and C person
• You will have 5 minutes to share info
CHECK ANSWERS
CHECK ANSWERS
CHECK ANSWERS
WARM UP
•
Describe an Irregular galaxy.
• Undefined shape, no symmetry
•
Describe a Spiral galaxy.
• Disk shaped, resembles a pin wheel
•
Describe an Elliptical galaxy.
• Round to flattened or elongated spheres
VIDEO
•
http://studyjams.scholastic.com/studyjams/jams/science/solar-system/universe.htm
GALAXIES
• What kind of galaxy is this?
• Irregular
GALAXIES
• What kind of galaxy is this?
• Spiral
GALAXIES
• What kind of galaxy is this?
• Elliptical
GALAXIES AND STAR QUESTIONS
• Instead of taking notes over this PowerPoint,
you will answer the questions as we go
• Pay attention because I did not highlight any of
the information for you
THE UNIVERSE…
…is space and everything in it.
GALAXIES
• A galaxy is a cluster of stars,
gas, and dust that are held
together by gravity.
• There are three main types of
galaxies:
• Irregular
• Elliptical
• Spiral
TYPES OF GALAXIES – IRREGULAR…
• Some galaxies do not
have definable, regular
shapes and are known
as irregular galaxies.
• They contain young
stars, dust, and gas.
TYPES OF GALAXIES – ELLIPTICAL...
• Elliptical galaxies look like
flattened balls.
• These galaxies contain billions
of stars, but have little gas and
dust between the stars.
• Because of the lack of gas and dust,
new stars cannot form in most elliptical
galaxies, and so they contain only old
stars.
TYPES OF GALAXIES –SPIRAL…
• Spiral galaxies consist of a flat,
rotating disk with stars, gas, and
dust and a central concentration of
stars, known as the bulge. The
bulge is surrounded by a much
fainter halo of stars.
• Contains middle aged stars
TYPES OF GALAXIES – BARRED SPIRAL…
• Our Milky Way galaxy has recently
(in the 1990s) been confirmed to be
a type of spiral galaxy known as a
barred spiral galaxy.
• Our Sun is located at the edge of the
Milky Way galaxy.
GALAXIES AND STARS
• How are galaxies classified?
• Where is our Sun located in the
Milky Way Galaxy?
VIDEOS
•
http://www.youtube.com/watch?v=UE8yHySiJ4A
•
Open Notes or uPad
•
Write 4 sentence about what you think or feel about what we have learned so far about
space.
• Include your name and data on the top
• Let this video clip motivate your
• http://www.youtube.com/watch?v=epTmlbJHZv4
WARM UP
•
Where is our Sun located in the Milky Way Galaxy?
• On the edge
•
Where size star is our Sun?
• Medium
LIFE CYCLE OF A STAR
• With your shoulder partner sort these
cards.
• Be prepared to justify your answer
LIFE CYCLE OF A STAR
• Volunteers to share your answers
LIFE CYCLE OF A STAR
• What might the Human Life Cycle sequencing activity
have to do with stars?
• If galaxies are made up of a collection of stars, dust, and
gas, then where do these stars come from?
• Stars undergo a life cycle that could be compared to a
human life cycle.
• Remember: a star has never been alive.
• Stars will go through a sequential cycle and then cease to
exist.
• A star’s life cycle depends on its mass.
•Open the Galaxies and
Star questions from
Friday
NEBULAE (PLURAL FOR NEBULA)
• Stellar Nebula- A gigantic
cloud of gas and dust from
which stars are made;
sometimes called a “Stellar
Nursery”
• Planetary Nebula- When a
star runs out of fuel to burn, its
outer layers of gas are blown
outward in the shape of a ring.
STARS
• A star contains hydrogen gas that forms helium through a
process known as nuclear fusion. Stars form when gravity
pulls together gas and dust from stellar nebula.
• It releases enormous amounts of energy which causes the
star to become very hot and glow.
• Vary in mass, size, and temperature
• Held together by gravity.
A STAR IS BORN…
• A star is made up of a large amount of gas, in a relatively small
volume.
• A stellar nebula, on the other hand, is a
large amount of gas and dust,
spread out in an immense
volume.
• All stars begin their lives as parts of stellar nebulas.
LIFE CYCLE OF A STAR
• With your shoulder partner sort these
cards.
• Be prepared to justify your answer
GALAXIES AND STAR CARDS
• Justify your answer
• Table 1
• Table 5
• Table 6
• Table 4
• Table 2
• Table 3
A STAR IS BORN…
• Gravity can pull some of the gas and dust in a nebula together.
• The contracting cloud is
then called a protostar.
• A star is born when the contracting gas and dust become so hot
that nuclear fusion begins.
LIFETIMES OF STARS…
• Before they can tell how old a star is, astronomers must
determine its mass.
• Medium mass stars, such as the Sun, exist for about 10
billion years.
• These are known as
main sequence stars.
LIFETIMES OF STARS…
• Stars with more mass have shorter lives than those with
less mass.
• Small stars use up their fuel more slowly than large stars,
so they have much longer lives, about 200 billion years.
LIFETIMES OF STARS…
Stars form in a stellar
nebula, from collapsing
clouds of interstellar gas
and dust. This is called a
protostar.
When a star runs out of
fuel, it will become a white
dwarf, neutron star, or
black hole.
The rest of the life
cycle depends on
the mass of the
star.
MAIN SEQUENCE STARS…
• Main Sequence is the stage in which stars spend the majority of their
lifetime.
• Small and medium stars first
become red giants.
• Their outer layers expand during the red giant phase.
• Eventually, the outer parts grow bigger still and drift out into space.
MAIN SEQUENCE STARS...
• The blue, white, hot core is left
behind causing a white dwarf
• When there is no more energy, it becomes a black
dwarf. It is the remaining burnt-out cinder left, as
the star goes out.
• A dying giant, or supergiant star, can suddenly explode.
Within hours, the star blazes millions of times brighter.
• The explosion is called a supernova.
NEUTRON STARS…
• After a star explodes, some material
from the star is left behind. This
material may become part of a
planetary nebula.
• The core will compress
and form a neutron star.
• Neutron stars are even
smaller and more dense
than white dwarfs.
BLACK HOLES…
• The most massive stars may have more than 40 times
the mass of the Sun. One might have more than five
times the mass of the Sun left, after it becomes a
supernova.
• The gravity of this mass is so strong that the gas is
pulled inward, packing it into a smaller and smaller
space. These massive stars become black holes when
they die.
GALAXIES AND STARS
• Protostar is like an infant
• Main Sequence like our Sun is like a toddler
through teen
• Red giant/supergiant is like an adult
through middle age
• White dwarf/black hole is like old age and
death
WARM UP
PREVIEW
•
http://www.youtube.com/watch?v=PM9CQDlQI0A
LIFE CYCLE OF A STAR
• Open Life Cycle of Stars
Graphic Organizer
• As we go through the
PowerPoint you will complete
their Life Cycle of Stars
Graphic Organizers and finish
completing their Galaxies and
Stars Questions which we will
talk more about tomorrow.
STAR LIFE CYCLE
Generally speaking, there are
two main life cycles for stars.
The factor which determines the
life cycle of the star is its mass.
1 solar mass = size of our Sun
Any star less than about three
solar masses will spend almost
all of its existence in what is
called the “Main Sequence”.
Star Basics
• Space may seem empty, but actually it is
filled with thinly spread gas, mostly
hydrogen, and dust.
• The dust is mostly microscopic grains of
carbon and silicon. In some places, this
material is collected into a big cloud of
dust and gas, known as a nebula.
• Stars form from collapsing clouds of gas
and dust. All stars begin in a nebula.
STELLAR NEBULA (A STAR NURSERY)
• Some gas and dust is pulled by gravity to the
core. As the region of condensing matter heats
up, it begins to glow. This is called a protostar.
SUN-LIKE STARS
• Temperature rises, and nuclear fusion begins.
This is the “birth” of the star. Nuclear fusion is the
atomic reaction that fuels stars. Fusion in stars is
mostly converting hydrogen into helium.
• Stars that are up to 1.5 times the mass of the Sun
are called “Main Sequence” stars and will burn for
a long time.
SUN-LIKE STARS
• A red giant is a large star that is reddish or
orange in color.
• It represents the phase in a star's life when
its supply of hydrogen has been exhausted
and helium is being fused into carbon. This
causes the star to collapse, raising the
temperature in the core. The outer surface
of the star expands and cools, giving it a
reddish color.
• Red giants are very large, reaching sizes of
over 100 times the star's original size.
RED GIANT
• Planetary nebulae form when a main sequence
star grows into a red giant and throws off its
outer layers and the core collapses.
• The term "planetary" comes from the 19 th
century, when astronomers saw what looked
like a new planet in their primitive telescopes.
• This was a time before people knew that there
were different types of galaxies. The name has
stuck ever since.
PLANETARY NEBULA
• The collapsed core left when a red giant loses its
outer layers is called a white dwarf.
• It is made of pure carbon that glows white hot with
leftover heat from the spent fuel. It will drift in
space while it slowly cools.
• It is the size of Earth, but very dense. A teaspoon
of the material would weigh as much as an
elephant.
WHITE DWARF
• A black dwarf is a white dwarf star that has
cooled completely and does not glow.
• It will drift in space as a frozen lump of
carbon. The star is considered “dead”.
BLACK DWARF
MASSIVE STARS
• All stars form from
collapsing clouds of gas
and dust found in a
nebula.
STELLAR NEBULA (A STAR NURSERY)
• Massive stars are stars that are between 1.5 to 3
times the mass of the Sun.
• A star with a much greater mass will form, live, and
die more quickly than a main sequence star.
• Massive stars follow a similar life cycle as small and
medium stars do, until they reach their main
sequence stage.
• This occurs because the gravity squeezes the star's
core and creates greater pressures, resulting in a
faster fusion rate.
MASSIVE STARS
• A red supergiant glows red because its outer layers
have expanded, producing the same amount of energy
over a larger space. The star becomes cooler.
• Red stars are cooler than blue or white stars. A
supergiant has the pressure needed to fuse carbon
into iron.
• This fusion process takes energy, rather than giving it
off.
• As energy is lost, the star no longer has an
outward pressure equal to gravity pushing in.
Gravity wins, and the core collapses in a violent
explosion.
RED SUPERGIANT
• A supernova is an explosion of a
massive star at the end of its life;
the star may briefly equal an entire
galaxy in brightness.
• At this point, the mass of the star
will determine which way it
continues in the life cycle.
SUPERNOVA
• Neutron Star
• If the star is at least 1.5 but less
than 9 times larger than the
Sun, the core left after the
supernova will collapse into a
neutron star. This is a star
composed only of neutrons.
NEUTRON STAR OR BLACK HOLE?
• Black Hole
• If the star is at least 9 or
more times larger than the
Sun, the core will continue to
collapse into a black hole, an
extremely dense area with a
strong gravitational pull that
light can not escape.
NEUTRON STAR OR BLACK HOLE?
• Our Sun is a medium
sized, main sequence star.
• It is the closest star to
Earth
LIFE CYCLE OF A STAR GRAPHIC ORGANIZER
CHECK FOR UNDERSTANDING
• Are Stars really alive?
• NO
• Then why are they compared to a
human life cycle?
EXTRA TIME
• Watch Savage Sun Video
• http://www.youtube.com/w
atch?v=H8Jz6FU5D1A
WARM UP
• Galaxies Key
• What is Absolute Magnitude?
• Absolute magnitude is the true
brightness of a star
• What is Apparent Magnitude?
• Apparent magnitude is how bright the
star looks in the sky from Earth
STAR DIFFERENCES
• Write on a blank page:
• Absolute magnitude is the true
brightness of a star
• Apparent magnitude is how bright the
star looks in the sky from Earth
STAR DIFFERENCES
• Would you agree or disagree to the
following statement:
• The light coming from the two
flashlights has the same absolute
magnitude and apparent magnitude
when they are placed side by side.
• Agree
STAR DIFFERENCES
• Would you agree or disagree to the following
statements:
• The apparent magnitudes of the lights have not
changed.
• Disagree
• The absolute magnitude of the lights has not changed.
• Agree
STAR DIFFERENCES
• How are the absolute and apparent magnitude affected?
• Distance
• Absolute magnitude is the brightness the star has if it is
measured at a standard distance from Earth. In
astronomy, this distance has been agreed to be 10
parsecs.
• A parsec is equal to 3.26 light years. Multiply 10 parsecs
by 3.26 ly, and it equals the 32.6 ly distance in the
definition you wrote earlier. The idea that a parsec is a
unit of measurement that astronomers have agreed to be
a standard is enough for students to know.
PUPPET PALS 2
•
With your shoulder partner and using Puppet Pals 2
•
Explain Absolute and Apparent Magnitude to a 6 th grader
• Include:
• Definitions
• Differences
• How can you remember each one
• Animation
• Extras:
• Each person must have a speaking part
• At least 60 seconds
WARM UP
WATER EDUCATION
• Jillian McDonald from the Upper Trinity Groundwater
Conservation District
• Inside Expectations:
• Current Events
• Star Life Cycle Notes
• Filling out survey
• Outside Expectations:
• Polite and Respectful
• Good Listeners
WARM UP
CLASSIFYING STARS
• Determine 4 different ways you could classify these
stars.
•
Write down you answers and be prepared to stand up and share at the front of
the class in the next 5 minutes
CLASSIFYING STARS
• Did you notice any pattern?
• Hertzsprung-Russell Diagram
CLASSIFYING STARS
• As a class let’s arrange our stars on a H-R Diagram
STAR DIFFERENCE
• Take a picture of our H-R Diagram, put the picture
into uPad, answers these question about it, and
turn it in.
1. What did you notice about the small stars?
2. What did you notice about the medium stars?
3. What did you notice about the large stars?
4. Which stars have the highest luminosity?
5. Why do you think the larger stars have more
luminosity?
HR DIAGRAM VIDEO
•
http://www.youtube.com/watch?v=jiSN95WX1NA
WARM UP
• What does luminosity mean?
• Brightness
VIDEOS
•
http://www.youtube.com/watch?v=HEheh1BH34Q
CLASSIFYING STARS
• Open HR-diagram Notes, Picture and
Questions
• Copy what is in yellow
THE HERTZSPRUNG-RUSSELL
DIAGRAM
(A.K.A. H-R DIAGRAM)
STAR CLASSIFICATION
• Stars can be classified in three ways:
• Size – How massive the star is
• Temperature – A stars color reveals its
temperature.
• Red stars have a cooler temperature, and blue
stars have a warmer temperature.
• Luminosity/Magnitude – The amount of light a star
gives off depends on its size and temperature.
BRIGHTNESS OR
MAGNITUDE
• How bright a star looks from Earth depends upon
both how far the star is from Earth and how bright
the star actually is.
• A stars brightness can be can be described in two
ways: apparent magnitude and absolute
magnitude.
APPARENT AND ABSOLUTE MAGNITUDE
• Apparent magnitude is the brightness of a star as seen from
Earth.
• Absolute magnitude is the true brightness of a star
• The brightness of the stars is compared to the brightness of
our Sun. We call this luminosity.
• The Sun has a luminosity of 1
H-R DIAGRAM
• Now you will create an H-R Diagram with your
group
• Make sure:
• You label at least 2 sides of the paper
• Everyone is participating and checking each
others work
• You have 20 minutes
STAR DIFFERENCE
• Take a picture of our H-R Diagram, import it your
notes, answers these question about it, and turn it
in.
1. What did you notice about the small stars?
2. What did you notice about the medium stars?
3. What did you notice about the large stars?
4. Which stars have the highest luminosity?
5. Why do you think the larger stars have more
luminosity?
W
A
R
M
U
P
CLASSIFYING STARS
• The H-R diagram was named for Ejar Hertsprung and Henry
Russell. Both saw patterns in star characteristics. The
diagram is often abbreviated as an H-R diagram.
• How is the H-R diagram a model?
• The H-R diagram models the different types of stars and
predicts star evolution, or aging, through its life cycle.
• What are some limitations of the model?
• It’s a snapshot of the state of a large collection of stars, it
doesn’t show every star, and it can become very crowded as
more stars are added, especially in the main sequence area.
•
1.
Interview your shoulder partner. Take turns recording each other answering these questions
(10 minutes)
What characteristics are used to classify stars?
1.
2.
How are stars classified on an H-R diagram?
1.
3.
A main sequence or small/medium star will become a red giant, planetary nebula, white
dwarf and then black dwarf. A massive star will become supergiant, supernova, and then a
neutron or black hole.
How is our Sun classified as a star?
1.
7.
Mass
How is the life cycle of a main sequence star different than that of a massive star?
1.
6.
No, it is a snapshot of the current stage of a collection of stars. Its cycle will continue as its
mass and temperature change and it is no longer burning hydrogen in its core .
What factor determines the life cycle a star will have?
1.
5.
The stars are plotted according to their magnitude and/or luminosity and temperature. They
fall into categories of main sequence, red giants, super giants, and white dwarfs.
Once a star has been identified as a main sequence star, will it always remain in that area
on an H-R diagram?
1.
4.
Luminosity (brightness) and/or absolute magnitude and temperature
Our Sun is a medium, main sequence star.
What star is closest to Earth?
1.
Sun
HR DIAGRAM
• An HR diagram shows the two most important
characteristics of stars, which are temperature and
absolute magnitude (brightness) and/or luminosity.
• Scientists plot the surface temperatures of stars and
their brightness on a graph.
CLASSIFYING STARS
• The yellow-white and blue-white stars have an overlap
where stars that appear white may belong to either
group. The white dwarfs are separated due to their
magnitude and temperature.
• This is not a complete model. There are billions of
stars, and this model only shows 21 stars. The graph
would be very crowded if many more stars were shown.
• Regardless of how many stars were added, they would
follow the same pattern as shown on the graph.
STARS FROM AFAR LAB
•
Complete the handout
•
Due tomorrow
•
Make sure you use color
WARM UP
1.
Once a star has been identified as a main sequence star, will it
always remain in that area on an H-R diagram?
1. No, it is a snapshot of the current stage
2. What factor determines the life cycle a star will have?
1. Mass
3. How is the life cycle of a main sequence star different than that
of a massive star?
1. A main sequence or small/medium star will become a red giant,
planetary nebula, white dwarf and then black dwarf.
2. A massive star will become supergiant, supernova, and then a
neutron or black hole.
• http://aspire.cosmicray.org/labs/star_life/hr_intera
ctive.html
CHAD DID IT
POOP
• Create a field guide for stars, including our
Sun, a supergiant, a giant, a main sequence
star, and a dwarf star. Provide a description,
relative age and life span, luminosity, and
temperature of each star. Finally, describe
how models such as a Hertsprung-Russel
diagram can be used for classification.