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Stars and Galaxies
Topic: Our Sun
• Objectives:
• I will learn the definition of a star
• I will learn the process of fusion in the
sun’s core
• I will be able to distinguish between the
inner and outer layers of the sun
Our Sun
• Our sun is just like many
other stars you see in
the night sky
• The sun is an average
middle-aged star made
up of an enormous ball
of hydrogen and helium
gas, producing energy
by fusing hydrogen into
helium in its core
• In the process, energy is
given off energy in the
form of radiation
What is a Star?
• A sphere of gases that
produces heat and light
through the ____ of
hydrogen
• Our sun is average star
Answer Bank
stars
Transfer
Cool
fusion
photosphere
4
Inner layers
• Core
• Radiative Zone
• Convection Zone
Core
• The core lies in the heart of
the sun and is 15,600,000
degrees Celsius
• The nuclear process know
as hydrogen fusion occurs
in the core
• During Hydrogen Fusion, 4
hydrogen combine to form 1
helium nucleus releasing
tremendous amounts of
energy
• 4 H = 1 He + energy
• Think Hydrogen Bomb!
The core, where nuclear
the Core,
fusionIn
takes
placePressures and Temperatures
are high
enough for Fusion to take place
let’s zoom
in and
what happens
H
H
H
HeHe
HeHe
In the process, energy is released
H
in the form of light &radiation
Fusion occurs when 4 hydrogen atoms (light element)
combines to form 1 Helium atom (heavier element)
Hydrogen, a lighter element is converted
into a heavier element, helium
What is Fusion?
• The combining of lighter elements to form
heavier elements
• In the Sun’s core, ___ hydrogen atoms (a
light element [don’t write] ) combine to form 1
helium atom (a heavier element [don’t write] ) &
energy is released
H
H
H
H
HeHe
HeHe
Answer Bank
stars
Transfer
Cool
photosphere
4
Radiative Zone
• In the radiative
zone, energy moves
radiates outward
from the core in the
form of light &
radiation
• It takes light
thousands of years
to move from the
core to the next
layer
• Temperature is
8,000,000 degrees
Celsius
Convection Zone
• Energy moves
through this zone
by convection
• Hot gases rise
toward the surface
while cooler gases
sink back down
• It’s behaves like a
giant pot of boiling
water
• Temp = 2,000,000
degrees Celsius
Outer Layers
• Photosphere
• Chromosphere
• Corona (not visible)
Photosphere
• Often called
the surface of
the sun
• Where light is
given off
• Temperatures
are around
6,000 degrees
Celsius
Chromosphere
• Above the
photosphere is the
chromopshere
• It’ temperature is
20,000 degrees
Celsius
• Reddish in color
Corona
• Largest layer of the
sun
• Extends millions of
kilometers in to space
• Hottest layer
• Temp= 2,000,000 C°
• Charged particles
leave the corona
creating a solar
wind
The Corona
seen during an eclipse
What are the Layer’s of the Sun?
•
•
•
•
Core- produces energy from _______ Fusion
Radiative Zone
Convection Zone
Photosphere- gives off light, surface of the
sun
• Chromosphere
• Corona- seen during an_____, gives off
solar wind
Answer Bank
stars
Transfer
Cool
hydrogen
4
eclipse
Sunspots
• “Cool” dark areas on
the Sun’s surface
• By studying sunspots,
we have discovered
that the Sun rotates
• Sunspots can last from
a few days to a few
months
• They represent areas
of intense Magnetic
activity
Sunspot Cycle
Maximums and Minimums
• Every 11 years our
sun goes through a
Sunspot cycle
• Our Sun has
periods of sunspot
maximums where
many sunspots are
visible
• Our Sun also has
periods of sunspot
minimums where
only a few sunspots
are visible
The Sun Spins
• From viewing sunspots, we know that
the sun spins!
Solar Flares
• A solar flare is a
violent explosion in the
Sun's atmosphere
• They release
tremendous amount of
radiation or energy in
the form of UV Rays,
X-rays, and gamma
rays
Prominences
• Prominences are huge
arching columns of gas on
the surface of the sun
• They erupt at speeds
ranging from 600-1000
km/s
• Ultraviolet light and x-rays
from prominences can
reach earth and cause
disruption in radio signals
Prominences
What Features can
be found on the Sun?
• Sunspots
– _____dark areas on
the surface of the
sun that occur in an
11 year cycle
(maximums/minimu
ms)
• Prominences
– Huge arching
•
Answer Bank
stars
Transfer
columns of gas
bursts
Cool
Solar Flares
photosphere
– violent ____ of
4
energy (radiation)
Summarize:
• Our sun is a star made mostly of
______ and helium gases
• _____ is the combining of lighter
elements to form _____
elements
• In the Sun’s____, 4 hydrogen
atoms a combine to form 1 ____
atom & energy is released
Answer Bank
heavier
Hydrogen
fusion
Helium
core
Topic: Light years and Stars
• Objectives:
• I will understand the concept of a light
year and how we use them to measure
distances in our solar system
• I will understand how stars vary in their
size, color, temperature and brightness
• I will learn how to classify stars on a H-R
Diagram
Light Years
• When astronomers first realized how far
away stars actually are, it became
apparent that a new unit of
measurement would be needed to
record their distances
• Stars are much farther away than the
planets in our solar system
• Distances between stars are measured
in light years!
Light Years
• A light year is the distance that light travels in
a year
• We use the light year to measure very distant
objects such as stars and galaxies
• Light travels at 300,000 km/s or about
9,500,000,000,000 trillion kilometers in one
year (9.5 x 1012 km/yr) 299 ,792 km/ s
• Nothing is faster than light
• If you travel at the speed of light, you would
become light
How Fast is That?
• A traveler, moving at the speed of light,
would circum-navigate the equator
approximately 7.5 times in one second
• How long do you think it takes light to
reach Earth from the Sun?
What are Light Years?
• A light yr is the distance that
light travels in a ______
• In 1 yr, light travels 9.5 trillion
kilometers or 300,000 km/s
• Light years are used to
measure very distant objects
such as stars and galaxies
Answer Bank
Average
Temperature
Absolute
Distance
Year
90%
hot
Parallax!
• How do we know the stars are farther away than the
planets in our solar system? We use parallax!
• The distance of a star is found by using parallax
• Parallax is the apparent shift in the position of an
object when viewed from two different positions
• You can easily observe parallax
• Hold your hand at arm’s length and look at one finger
with your left eye and then with your right eye
• What you will notice is that your finger appears to
change position with respect to the background
Parallax Continued…..
• Now try the same experiment with your
finger closer to your face
• What do you observe?
• The closer an object is to the observer,
the greater its parallax
• We can measure parallax of relatively
close stars in order to determine their
distance from earth
Calculating Parallax
What is Parallax?
• Parallax is how we
measure the ____ to
stars in light years
• It is found by viewing
an object from 2
fixed locations
Answer Bank
Average
Temperature
Absolute
Distance
Year
90%
hot
Star Characteristics
Yellow Stars like are
Sun are average in
brightness & temperature
Blue Stars are
large hot and bright
Red Stars are
small cool and dim
What’s the relationship between
star color, size, & temperature?
• Large Blue-white stars are ___ &
bright
• Red stars are cool & dim
• Yellow stars, like our sun are
____ in temperature and bright
ness
Answer Bank
Average
Temperature
Absolute
Distance
Year
90%
hot
H-R Diagram
• In the early
1900’s, Ejnar
Hertzsprung
and Henry
Russell found a
way to classify
stars
• They classified
stars by their
temperature
and brightness
http://www.youtube.com/watch?v
=HEheh1BH34Q&feature=fvw
Blue Massive Stars
Supergiants
Giants
Sun
Hot White Dwarfs
Red Dwarfs
Hot Bright
Blue Stars
Yellow Orange
Average Stars
Cool Red
Dim Stars
H-R Diagram
•
Hertzsprung and
Russell came up
with a graph that
shows the
relationship
between
temperature and
brightness
• Notice where the
cool small red
dwarfs stars are
located
• Notice where the
massive hot blue
dwarfs stars are
located
Blue Massive Stars
Supergiants
Giants
Sun
Hot White Dwarfs
Red Dwarfs
Hot Bright
Blue Stars
Yellow Orange
Average Stars
Cool Red
Dim Stars
What is the H-R Diagram?
• A graph that compares the
brightness, ______ and
color of a star
• _____ magnitude is the true
brightness of a star
Answer Bank
Average
Temperature
Absolute
Distance
Year
90%
hot
Main Sequence Stars
• Our sun is a yellow
Main Sequence
Star
• Main Sequence
Stars that fit into a
diagonal band that
run from the upper
left to the lower
right corner
• Main Sequence
Stars contain
large, hot blue
stars, as well as
small cool red
stars
• 90 % of all stars
are Main
Sequence
Blue Massive Stars
Sun
Red Dwarfs
Hot Bright
Blue Stars
Yellow Orange
Average Stars
Cool Red
Dim Stars
What are Main Sequence Stars?
• The diagonal band of
stars in an H-R
diagram
• Blue, white, yellow,
orange, red stars
• ____ of the stars we
see at night are main
sequence
Answer Bank
Average
Temperature
Absolute
Distance
Year
90%
hot
Summarize:
• _______ is how we measure star
distances when viewed from two
fixed locations as we orbit the sun
• Large stars are ____ and small
stars are ____
• Hot stars are ______ in color
• Cooler stars are ______in color
• An H-R diagram is a graph that
relates star ________ to star
________
Answer Bank
Brightness
temperature
Parallax
bright
Absolute
blue
red
dim
Topic: Star Lifecycle
• Objectives:
• To learn the difference between the
lifecycle of a massive blue main
sequence star with a yellow main
sequence star like our sun
• To understand how nucleosynthesis
occurs in stars
• Star size:
http://www.youtube.com/watch?v=HEheh
1BH34Q
Star Size
All star’s form in a nebula
A star will begin it’s main sequence when hydrogen fusion begins
But what determines the size of a star?
Gravity wants to crush the star
So why doesn’t it?
Because the outward pressure
Or force of energy from
Fusion balances out the
inward force of gravity
This keeps the star in a
state of balance or equilibrium!
What determines the size of a
main sequence star?
• A balance between
the ____ pull of
gravity and the
outward push of
energy created by
fusion
Answer Bank
Neutron
Lighter
Inward
Red
Fusion
White dwarf
short
Temperature & Pressure
Affect Star Life
Full
Hydrogen
Empty
Large massive
blue stars have
Short lives
Because they have
higher pressures &
temperatures in the
Core, therefore they
run through their
Hydrogen fuel
source faster
Hydrogen
Empty
Full
Hydrogen
Empty
Star like our
sun have
average lives
Full
Small Red dwarf
stars have long live
because of cooler
temperatures
in the core
How does temperature and
pressure effect the life of a star?
• Temperature and pressure increase
the rate of fusion in a stars core
• Hot blue stars have ____ lives
• Cooler ___ stars have long lives
• Yellow stars like our sun have
average lives
Answer Bank
Neutron
Lighter
Inward
Red
Fusion
White dwarf
short
Massive Blue Star Lifecycle
In a massive blue stars core, hydrogen fuses
together to form Helium for most of its
short Main sequence life
Eventually hydrogen starts
to run out and helium
starts to accumulate
Helium
Carbon
Helium
As a result gravity wants
to crush the star, pressures &
temperatures increase, & the star
begins fusing helium into carbon
Over time the outward pressure or
force of energy from fusion becomes
stronger than the inward force of gravity &
the star begins to swell & cool changing its color in the process
Massive Blue Star Lifecycle
Temperatures continue to
increase in the core, & the
star begins fusing Carbon
into Oxygen
Carbon
Oxygen
At this point the star
is now a supergiant
Helium
Carbon
Helium
Hydrogen
But fusion doesn’t stop
Just yet!!!!!
Massive Blue Star Lifecycle
Finally, as temperatures continue to increase the
star will begin fusing oxygen into Iron
Iron
Carbon
Oxygen
Oxygen
Helium
Carbon
Carbon
Helium
Helium
Hydrogen
Hydrogen
Near the end of it’s life
The blue massive star
resembles an onion with
layers of different elements
This process is called
Nucleosynthesis—Where
Lighter are elements are created
into heavier elements through
Fusion in a star
Massive Blue Star Lifecycle
In massive blue stars
Elements up to the size of
Iron-element 26 are created
Through fusion
Iron
Carbon
Oxygen
Oxygen
Helium
Carbon
Carbon
Helium
Helium
Hydrogen
Hydrogen
Massive Blue Star Lifecycle
At a certain temperature, Fusion can no longer
occur and the outward energy stops,
at this point gravity takes
Black Hole Neutron Star Over and crushes the star
Iron
Carbon
Oxygen
The star explodes
into a super nova!!!
Helium
Carbon
Helium
Hydrogen
Depending upon the stars
initial mass or size, It will end up
as either a neutron star or Black hole
Massive Blue Star Lifecycle
When the star explodes, it blasts all The elements
into space, seeding the universe with Elements
to make new stars, planets, people and buildings
Supernovas are so hot & bright, They produc
all other elements heavier than iron
Iron
Carbon
Oxygen
Helium
Carbon
Helium
Hydrogen
What is Nucleosynthesis?
• The creation of new elements in
stars by fusing lighter elements into
heavier elements (fusion)
– Fusion in Blue Massive stars create
elements as heavy as ______
– At this point fusion stops and the star goes
supernova
– When a blue star goes supernova (explodes)
it creates elements _____than Iron such as
gold and lead
Answer Bank
Neutron
Lighter
Inward
Red
Iron
heavier
short
Yellow Star (Sun) Star Lifecycle
Our sun’s core will fuse hydrogen into
Helium for most of its 10 billion
year old Main sequence life
Carbon
Helium
Helium
Throughout this time Helium
Will accumulate in its core
As a result of gravity
crushing the star, pressures
& temperatures increase & the
star begins fusing helium into carbon
Over time the outward pressure or force of energy from fusion
becomes stronger than the inward force of gravity & the star
begins to swell & cool changing its color in the process
Yellow Star (Sun) Star Lifecycle
Temperatures continue to
increase in the core, & the
star begins fusing Carbon
into Oxygen
Carbon
Helium
Oxygen
Helium
Carbon
Helium
Hydrogen
At this point the star
is now a Red Giant
Unlike a blue star, temperatures
and pressure are not high enough
To produce Iron through fusion
Fusion stops at OXYGEN
Yellow Star (Sun) Star Lifecycle
Carbon
Helium
Oxygen
Helium
Carbon
Helium
Hydrogen
Instabilities in the
balance Between
Gravity & outward
force or Pressure
of fusion result in
abrupt explosions
that blow away
the outer layers
of the star
The result is a
planetary nebula
with a hot white
dwarf star in the middle
Yellow Star (Sun) Star Lifecycle
Eventually the
Gases are expelled
Leaving behind
A white dwarf star
A white dwarf
star is what remains
of an average star
like our sun after
Running out of fuel
It’s about
the size of earth
What is the difference between a massive
blue star and Yellow like star’s lifecycle?
• Blue Star: Nebula Main sequence
massive blue star supergiant
supernova black hole or _____ star
• Yellow Star: Nebula Main
sequence yellow star red giant
planetary nebula____ ____
Answer Bank
Neutron
Lighter
Inward
Red
Fusion
White dwarf
short
Sun Lifecycle
Star Lifecycle
Summarize:
????
????
????
????
Answer Bank
White dwarf
Black hole
red giant
Supernova
10
????
????
• Our sun has ______ billion year life span
Topic: Galaxies & The Big Bang
• Objectives:
• I will be able to define a galaxy and
classify the 3 different types of galaxies
• I will understand the Big Bang theory and
the evidence supporting it
Galaxies
• We are on earth, all
going around the sun
• However, does the sun
orbit anything?
• The sun is one star
among many in our
Galaxy
• A galaxy is a group of
billions of stars, gas and
dust held together by
gravity
Billions and Billions
• When we look out into
deep space we see
billions of galaxies
• Each galaxy contains
billions of stars
• So space is made
mostly up of star and
galaxies
Galaxies: 4 Types
• A galaxy is a group of billions of stars, gas and
dust held together by gravity
• We classify galaxies into 3 types:
-Spiral: disc shaped, have long spiral arms
-Barred spiral: same as spiral but has
bar going through the middle of it
-Elliptical: sphererical or oval shaped
more common
-Irregular: small irregular shaped
less common
Spiral Galaxies
Elliptical Galaxies
Irregular Galaxies
What is a Galaxy?
• A group of billions of ___, gas and dust held
together by gravity
• 4 types:
Answer Bank
-Spiral: disc shaped, have long spiral arms
30,000
Red shift
-Barred spiral: same as spiral but with bar in the
microwaves
middle
Stars
-Elliptical: most common, spherical or oval
100,000
shaped
expansion
-Irregular: least common, small irregular shaped
Milky Way Galaxy
• Contains over 200 billion stars
• The visible disk of stars is about 100,000 light
years across
• The sun is located 30,000 light years out from its
center
• All stars orbit around the central region
• Based on a distance of 30,000 light-years and a
speed of 235 kilometers a second, the sun orbits
around the center of the galaxy once every 240
million years
Milky Way Continued…..
• The Milky Way is usually classified as a
normal spiral galaxy
• It is difficult to know for sure because it is
impossible to see our galaxy from the outside
• You can see the Milky Way stretching across
the night sky as a faint band of light
• All of the stars you can see in the night sky
belong to the Milky Way
Our Sun and
Solar System
Is located 26,000
Light years form Our
Our galactic center
Sun
Our Milky Way
is 1 star
galaxy is 100,000 among 5
light years across billion
What is the Milky Way Galaxy?
• A 10 billion year old barred
spiral galaxy made up of
around 400 billion stars and
_____ light years across
• Our sun and solar system is
located ____ light years
Answer Bank
from the center
30,000
Red shift
microwaves
Stars
100,000
expansion
Big Bang Theory
• About 13.7 billion years
ago our universe formed
• All matter existed in an
incredibly hot dense
state of hydrogen and
helium
• After it exploded, it
expanded & cooled into
stars & galaxies
Big Bang Theory
•
The big bang theory
or model states that
all matter in the
universe was
released in a
massive expansion
of time and space
What is the Big Bang Theory or Model?
•
Theory or model that
states that all matter in
the universe was
released in a massive
_____ of time and space
13.7 billion years ago
Answer Bank
30,000
Red shift
microwaves
Stars
100,000
expansion
Evidence for the Big Bang Theory
•
•
Evidence for the big
bang theory came
through two huge
pieces of evidence:
red shift and microwave
background radiation
Evidence for the Big Bang Theory
•
•
•
Red shift showed that all galaxies and stars are
moving away from each other and in fact expanding
If objects are expanding then at one point they must
have been closer together
Here’s how it works:
What Evidence supports the Big Bang Theory?
• Red shift from distant stars
and galaxies
• Cosmic background radiation
in the form of _________
Answer Bank
30,000
Red shift
microwaves
Stars
100,000
expansion
Summary
• A ____ is a group of billions of____,
gas and dust held together by gravity
• We live in the _____ _____ which is
_______ light years across
• ____ _____ and _____ radiation is
evidence for the big bang & and
expanding universe
• Our universe is ____ BYO (billion
years old), our galaxy is _____ BYO
Answer Bank
Galaxy
13.7
Red shift
microwaves
Stars
100,000
10
Milky way