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J. Nguyen – Physical Science
53
Chapter 30 Standards
1d. Students know the evidence indicating that the planets are
much closer to Earth than the stars are.
2a. Students know why the solar system is located in an outer edge
of the disc-shaped Milky Way galaxy, which spans 100,000 light
years.
2b. Students know galaxies are made of billions of stars and
comprise most of the visible mass of the universe.
2c. Students know the evidence indicating that all elements with an
atomic number greater than that of lithium have been formed by
nuclear fusion in stars.
2d. Students know that stars differ in their life cycles and that visual,
radio, and X-ray telescopes may be used to collect data that
reveal those differences.
2g. *Students know how the red-shift from distant galaxies and the
cosmic background radiation provide evidence for the “big bang”
model that suggests that the universe has been expanding for
10 to 20 billion years.
J. Nguyen – Physical Science
A. What are Stars?
1. A star is a ball of gases that gives off a
tremendous amount of electromagnetic
energy.
2. The energy comes from nuclear fusion
occurring inside the star’s core.
3. The sun is a star.
J. Nguyen – Physical Science
B. Composition of Stars
1. Stars are composed of the same elements
that are found on Earth.
2. Unlike Earth, hydrogen is the most
common element and helium is the second
most common found in stars.
3. Carbon, oxygen, nitrogen, and calcium
make up the remaining mass of stars.
J. Nguyen – Physical Science
C. Temperature of Stars
1. Stars vary in temperature with most ranging
from 2,800oC to 24,000oC.
2. The temperature of a star determines its
color.
3. Scientists can use both the color and
temperature to classify a star.
J. Nguyen – Physical Science
D. Sizes and Masses of Stars
1. Stars vary in size and mass.
2. Some dwarf stars are about the same size as
Earth.
3. Medium-sized stars are the size of our sun.
4. Some giant stars have diameters that are
1,000 times the sun’s diameter.
5. Stars may have the same, more or less mass
than the sun.
J. Nguyen – Physical Science
E. Stars have two kinds of motions.
1. Apparent motion is the motion
visible to the unaided eye in the
dark sky.
a. This apparent motion is due to
the movement of Earth.
b. If a picture is taken of stars
moving over the course of a
night, they look like they are
moving counter-clockwise
around a central star called
Polaris, or the North Star.
J. Nguyen – Physical Science
2. Actual motion is the motion of stars measured
with high-powered telescopes and other
instruments. There are three actual motions:
a. They rotate on an axis.
b. They may revolve around another star.
c. They move away from or toward the Earth.
i. Doppler effect is the shift in the wavelength
of light.
ii. Blue shift is the result of a star moving
towards Earth.
iii. Red shift is the result of a star moving away
from Earth.
J. Nguyen – Physical Science
J. Nguyen – Physical Science
F. Movement of stars during the year.
1. As Earth orbits the sun, different stars
become visible during different seasons.
2. Polaris is our North Star.
3. Polaris is located directly above the North
Pole and does not appear to move.
4. Some stars are always visible in the night sky,
these stars always circle Polaris.
5. They are called circumpolar stars.
a. Example: The Little Dipper
J. Nguyen – Physical Science
J. Nguyen – Physical Science
G. Distances to Stars
1. Because outer space is so BIG, distances
between the stars and the earth are measured in
light-years.
2. Light-year is the distance that light travels in one
year.
3. The speed of light is 300,000 km/s and travels
about 9.5 trillion km in one year.
4. Light from the sun takes about 8 minutes to
reach the Earth, so the sun is 8 light-minutes
from Earth.
5. The further away a star is, the greater the
number of light years.
J. Nguyen – Physical Science
H. Two scales are used to describe the brightness of
stars.
1.
Apparent magnitude is the brightness of a star as it
appears from Earth.
a. Astronomers use special instruments attached to
the end of telescopes to measure apparent
magnitude.
b. After they are observed, the stars are assigned a
number. The lower the number on the scale, the
brighter the star.
2. Absolute magnitude is how bright a star would
appear if they were all the same distance from Earth.
a. The lower the absolute magnitude number, the
brighter the star.
J. Nguyen – Physical Science
Write 5 questions for this section.
Highlight key words and phrases.
Draw a picture.
J. Nguyen – Physical Science
Summary (one paragraph) – Page 2
A star is ________________________________.
The two most common elements found in stars
are __________ and __________. Stars have
two kinds of motions: ___________ and
________. Light-year is ___________________.
The two scales used to describe the brightness of
stars are ____________ and ___________.
J. Nguyen – Physical Science
A. Classification of Stars
1. Scientists have developed theories about the
evolution of stars by studying stars in different
stages of development.
2. Astronomers use the absolute magnitude of stars
and their luminosity (the total amount of energy
they give off each second) to plot them on a
graph.
3. The graph that results from this information is
called the Hertzsprung-Russell diagram or the HR diagram.
J. Nguyen – Physical Science
B. The H-R Diagram
1. Scientists use the H-R Diagram to describe the life
cycles of stars.
2. Hottest temperatures are always plotted on the left of
graph and the highest luminosities are always at the
top.
3. The temperature and luminosity of most stars falls
within a band that runs diagonally through the middle
of the H-R diagram.
4. This band is known as the main sequence. Stars
within this band are known as main sequence stars.
Our sun is a main sequence star.
J. Nguyen – Physical Science
J. Nguyen – Physical Science
C. The Life of Stars
1. The H-R diagram shows that the life of a star is a
sequence of events called stellar evolution.
2. Stellar evolution includes the changes in the life of a
star from life to death.
3. Stars go through the following stages in their lifetime:
a. Nebula (Protostar)
b. Main Sequence (Main Sequence Star)
c. Leaving the Main Sequence (Red Giant or Red
Supergiant)
d. Final Stages of a Sunlike Star (Planetary Nebula
and White Dwarf)
e. Final Stages of Massive Stars (Supernova and
Neutron Star)
J. Nguyen – Physical Science
D. Nebula – First Stage
1. A star begins in a nebula.
2. Nebula is a cloud of gas and dust and most are
composed of about 70% hydrogen, 28%
helium, and 2% other elements.
3. A nebula is continually spinning.
4. As it spins, it gets smaller and smaller and
denser and denser.
5. Gravity and pressure take the materials of a
nebula and pack it tighter and tighter.
6. A nebula can produce more than one star.
J. Nguyen – Physical Science
7. The shrinking and spinning regions of a nebula
flatten out into a disk of matter called a protostar.
8. As more and more matter falls into the protostar,
pressure and temperature increase.
9. Temperature increases until about 10,000,000°C
and then hydrogen fusion begins. Hydrogen
fusion is a type of nuclear fusion that changes
hydrogen into helium.
J. Nguyen – Physical Science
E. Main-Sequence – Second Stage
1. This is the second and longest stage of a
star’s life. The stars in this stage are known
as main-sequence stars.
2. Nuclear fusion continues.
3. Enormous amounts of energy released from
nuclear fusion.
4. Gravity keeps the star a stable size.
5. The sun is a main-sequence star.
J. Nguyen – Physical Science
F. Leaving the Main Sequence – Third Stage
1. A star enters its third stage when almost all of the
hydrogen atoms within its core have fused into
helium atoms.
2. Instead of the core making more helium, the core
begins to convert helium into carbon.
3. Without hydrogen for fuel, the star’s core contracts
under the force of its own gravity. The core shrinks!
4. As it shrinks, it gets hotter and has to transfer that
heat elsewhere.
5. It transfers that heat into a shell that surrounds the
core.
6. Can form two main types which depend on size –
red giant stars and red supergiants.
J. Nguyen – Physical Science
7. Red Giants
a. Because of both hydrogen fusion and helium
fusion, the outer shell of star expands or gets
bigger.
b. The third stage of stellar evolution involves a
main sequence star becoming a red giant.
c. They are known as red giants because their
outer shells become red as they cool down.
d. Red Giants are 10 times bigger than the sun.
J. Nguyen – Physical Science
5/22/2017
8. Red Supergiants
a. Main-sequence stars that are larger than the
sun will become larger than giants in their
third stage. Instead of becoming red giants,
they become red supergiants.
b. Red Supergiants are at least 100 times bigger
than the sun.
J. Nguyen – Physical Science
G. Final Stages of a Sunlike Star
1. Planetary Nebulas
a. For medium to small sized main sequence stars,
the next stage in its life is as a planetary nebula.
b. Once all helium atoms have fused into carbon
atoms, there is no energy left in the stars and
their outer shell of gases drift away.
c. As these gases drift away a cloud of gas forms
around the core of the star which is known as a
planetary nebula.
J. Nguyen – Physical Science
2. White Dwarfs
a. As the planetary nebula disappears, gravity causes
the remaining matter in the star to collapse inward.
The star continues to collapse inward until it cannot
be pressed down any further.
b. What is left is an extremely dense core of matter
known as a white dwarf.
c. A white dwarf is about the size of Earth and still
shines for billions of years before it cools completely.
d. As it cools, a white dwarf gets dimmer and dimmer.
e. When a white dwarf no longer shines it is known as a
black dwarf.
J. Nguyen – Physical Science
H. Final Stages of Massive Stars
1. Novas and Supernovas
a. Stars that are larger than our sun leave the red
supergiant stage of their life and enter the
nova/supernova stage.
b. A nova is a large explosion of the star which is caused
by the increase pressure of the star as it converts helium
into carbon.
c. A nova can cause a star to be many thousands of times
brighter than normal. However, within a few days, the
nova begins to fade to its normal brightness.
d. Supernovas are thousands of times more violent than a
nova.
J. Nguyen – Physical Science
Nova/Supernova
J. Nguyen – Physical Science
2. Neutron Star
a. After massive stars explode in a nova or
supernova, their core may contract into a very
small and dense ball of neutrons. This is
called a neutron star.
b. Neutron stars still shine but not as brightly as
they had originally.
c. Due to their large size at this stage, neutron
stars still shine more brightly than our sun.
J. Nguyen – Physical Science
3. Black Holes
a. Some massive stars produce leftovers that
are too big to become neutron stars.
b. The massive stars can contract under its
greater gravity.
c. Due to the great force of contraction, the core
of the star crushes. This leaves a hole in
space known as a black hole.
d. The pull of gravity of a black hole is so great
that nothing, not even light, can escape it.
J. Nguyen – Physical Science
J. Nguyen – Physical Science
Nebula
Protostar
Low mass
Main sequence star
High Mass
Main sequence star
Red Giant
Red Supergiant
White Dwarf
White Dwarf
Nova
Supernova
Neutron
Star
J. Nguyen – Physical Science
Black
Hole
Write 10 questions for this section.
You should have 15 questions so far.
Highlight key words and phrases.
Draw a picture.
J. Nguyen – Physical Science
Summary (one paragraph) – Page 5
Astronomers use absolute magnitude and
___________ to plot stars on a ______ diagram.
Our sun is a _____________ star. Stellar
evolution is _________________________.
Stars go through four stages which are:
1. _______________, 2. ______________,
3. _______________, and 4. ______________.
J. Nguyen – Physical Science
A. Constellations
1. Constellations are the patterns of stars and
the region of space around them.
2. Although the stars that make up a pattern
appear to be close together, they are not all
the same distance from Earth.
J. Nguyen – Physical Science
B. Patterns in the Sky
1. For more than 3,000 years, people have
observed and recorded the patterns of stars that
they see in the sky.
2. Astronomers recognize 88 constellations.
J. Nguyen – Physical Science
C. Multiple-Star Systems
1. Stars are not always solitary objects isolated
in space.
2. When two or more stars are closely related,
they form multiple-star systems.
3. Binary stars are pairs of stars that revolve
around each other and are held together by
gravity.
J. Nguyen – Physical Science
D. Galaxies
1. Galaxy is a large-scale group of stars, gas,
and dust that are bound together by gravity.
2. Galaxies are the major building blocks of the
universe.
3. Galaxies contain billions of stars.
4. Astronomers estimate that the universe
contains hundreds of billions of galaxies.
J. Nguyen – Physical Science
E. There are three types of galaxies.
1. Spiral Galaxy
a. Spiral galaxy is type of galaxy with a nucleus of
bright stars and flattened arms that swirl around
the nucleus.
b. The spiral arms contain millions of young stars,
gas, and dust.
c. Some spiral galaxies have a bar of stars that runs
through the center which is known as barred
spiral galaxies.
J. Nguyen – Physical Science
5/22/2017
2. Elliptical Galaxy
a. Elliptical galaxy is a type of galaxy that varies in
shape from nearly spherical to flattened disks.
b. These galaxies are very bright in the center and
do not have spiral arms.
c. They do not have young stars and contain very
little dust and gas.
J. Nguyen – Physical Science
3. Irregular Galaxy
a. Irregular galaxy is a galaxy that has no
particular shape.
b. These galaxies tend to be smaller and fainter.
c. Stars are unevenly distributed throughout this
galaxy.
d. This galaxy is made of young and old stars.
J. Nguyen – Physical Science
F. The Milky Way Galaxy
1. Our solar system belongs to the Milky Way
Galaxy which is a spiral galaxy.
2. The galaxy has a diameter of about 100,000
light years and rotates.
3. Milky Way is a cloudlike band of stars that
stretches across the sky, has a milky
appearance and is the disk of the galaxy.
4. The sun, which is located in one of the spiral
arms, revolves around the galaxy at a speed
of about 250 km/s and is one of a billion stars
in this galaxy.
J. Nguyen – Physical Science
J. Nguyen – Physical Science
A. The Expanding Universe
1. Astronomers have been able to record data of the
locations of galaxies over the years. They have
found that our universe is expanding (getting
bigger).
J. Nguyen – Physical Science
B. The Big Bang Theory
1. There are several theories to explain why the universe
is expanding but the most widely accepted theory is
the big bang theory.
2. The big bang theory states that billions of years ago,
all the matter and energy in the universe were
compressed into an extremely small volume. Then
about 14 billion of years ago, a sudden event sent all of
the matter and energy outward in all directions.
3. As the universe expanded, some of the matter
gathered into clumps that evolved into galaxies.
4. Today, the universe is still expanding, and the galaxies
continue to move apart from one another.
J. Nguyen – Physical Science
Write 5 questions for this section.
You should have a total of 20 questions.
Highlight key words and phrases.
Draw a picture.
J. Nguyen – Physical Science
Summary (one paragraph) – Page 6
Constellations are _________________________.
Binary stars are __________________________.
Galaxies are _____________________________.
The three types of galaxies are __________,
__________, and __________. Our solar system
belongs to the ____________ Galaxy which is a
_________ galaxy.
J. Nguyen – Physical Science
Notes Points
Name __________________________________ Period _______
Points
Earned
Chapter 30 Notes
Highlight Key Words/Phrases
Points
Possible
2
Copy Notes: pictures + color + label
20
Questions: 20 questions + arrows
10
Summary: 3 paragraph(s)
15
Drawings: 3 drawing(s)
6
TOTAL
J. Nguyen – Physical Science
53
Focus on Constellations
J. Nguyen – Physical Science
Characteristics of Constellations
 There are 88 of them recognized
 Many of them are named after Greek Mythology
Characters
 Each star in a constellation is labeled with a greek
letter of the alphabet to let you know the order of
brightness of the star
 Constellations were first developed to help in
navigation and also to help farmers
J. Nguyen – Physical Science
Greek Alphabet and the Constellations
 α- alpha- brightest star in constellation
 β- beta- second brightest star
 γ- gamma- third brightest star
 δ- delta- fourth brightest star
 ε- epsilon- fifth brightest star
 ζ- etc.
η
θ
ι
κ
J. Nguyen – Physical Science
ANDROMEDA
ANDROMEDA
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Science
J. Nguyen – Physical Science
AQUARIUS
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URSA MAJORCALLISTO
URSA MAJOR
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J. Nguyen – Physical Science
ORION
J. Nguyen – Physical Science
J. Nguyen – Physical Science
J. Nguyen – Physical Science