Light, The H-R Diagram, and Stellar Evolution Lab
(94 points)
Name:
Group #:
Period:
Objective: To construct an H-R Diagram and model the life cycles of different types of
stars.
Question: How can the general life cycles of different types of stars be shown using
balloons?
Hypothesis: ____________________________________________________(1 pt.)
Introduction:
For most of history, people had very limited knowledge of space. They saw planets
and stars as points of light in the night sky. However, they did not know what those bodies
were made of and how far from Earth or from each other they were. Early observers made
guesses about stars on basis of their appearance and the ways they seemed to move in the
sky. We still have much to learn about the universe. Within the last few hundred years,
however, new tools and scientific theories have greatly increased our knowledge. In this
lab, you will learn about the ways in which astronomers explore and study space, observe
several types of light broken down into colors (spectra), construct your own H-R Diagram
of known stars, and model different types of stars’ life cycle.
Part 1: Getting Started
Procedure –
1. In the appropriate boxes below, draw detailed diagrams of the two different
visible-light telescopes, making sure to label everything in each diagram. (12 points)
a. Parts to include for the reflecting telescope – eyepiece, concave(primary)
mirror, flat (secondary) mirror, focus, focal length
b. Parts to include for the refracting telescope – focal length, focus,
objective lens, eyepiece, and incoming light
____________ Telescope
____________ Telescope
2. There three different types of spectra that study the light a body gives off. In
the spaces provided, name the three different types of spectra and give a short
description. (6 points)
a. _________________________________________________________
_________________________________________________________
b. _________________________________________________________
________________________________________________________
c. _________________________________________________________
_________________________________________________________
3. Using the diagram that details the process of Nuclear Fusion below, answer the
following questions on a separate piece of paper (8 points).
1. As shown in Step 1, what does a hydrogen nucleus consist of?
2. When the two hydrogen fuse, what is the composition of the resulting nucleus?
What particle has been changed?
3. In Step 2, what fuses with the nucleus produced at the end of Step 1? What does
the resulting atom consist of?
4. What is the final product of nuclear fusion in the sun? OF what does this nucleus
consist?
5. What is produced in great amounts throughout every step of nuclear fusion?
Part 2: Observing Spectra
Background – Visible light is made up of different colors that can be separated into a
rainbow band called a spectrum. Astronomers gain information about the characteristics
of stars by spreading their light into spectra (spectra is the plural of spectrum). A
spectroscope is a device that produces spectra. In most spectroscopes, diffraction
gratings are used to separate light into different colors. The colors with the longest
wavelengths appear farthest from the slit in a spectroscope. The colors with the shortest
wavelengths appear closest to the slit.
Objective –
The objective of this activity is to build a spectroscope and observe the spectra of three
different light sources, and identify ways in which the spectra of light differ.
Materials –
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Shoebox with lid
Ruler
Scissors
Diffraction grating
Tape
Index card
Pencils or markers in a variety of colors
Incandescent light
Fluorescent light
Tissue
Procedure –
1. Cut a hole measuring 6.5 cm by 3 cm in the CENTER of each end of the shoebox.
Make sure that the holes line up.
2. Use a piece of tissue to clean off any fingerprints on the piece of diffraction
grating. Handle the diffraction grating by its edges so that you do not get
fingerprints on it.
3. On the inside of the box, tape a piece of diffraction grating over one of the holes.
4. Cut an index card in half and tape the halves over the OUTSIDE of the other hole
as shown below. Leave a very narrow slit between the two halves of the index card.
Check with Mr. Spangler that your spectroscope is made correctly before moving on
(1 point for check). _____
5. Put the lid on the shoebox. Then, as a class, go outside.
6. Look through the hole covered by the diffraction grating, aiming the spectroscope
at the sky. CAUTION: Never look directly at the Sun. Observe the spectrum of
colors you see to the left of the slit.
7. Repeat step 6 while aiming the spectroscope at an incandescent light, and then at a
fluorescent light.
8. For each light source, draw the data table below the spectrum of colors you see to
the left of the slit. Describer the colors and patterns in the spectrum, and label
the light source.
Table. Spectra of Different Light Sources (9 points)
Light Source
Drawing
Description
Analysis Questions (7 points)
*Please answer these questions on a separate piece of paper
1.
2.
3.
4.
5.
What problems did you experience in observing the spectra?
How did the spectra differ from one another?
Which light sources produced bands of colors with no breaks in them?
Which source produced a band of colors broken by dark stripes?
On the basis of your observations, which color has the shortest wavelength? Which
color has the longest wavelength?
6. How might the spectra look different if the slit at the end of the spectroscopes
were curved instead of a straight line?
Part 3: The Hertzsprung - Russell diagram
Background – Astronomers use two basic properties of stars to classify them. These two
properties are luminosity and surface temperature. Luminosity refers to the brightness
of the star relative to the brightness of our sun. Astronomers will often use a star’s color
to measure its temperature. Stars with low temperature produce a reddish light while
stars with high temperatures shine with a brilliant blue-white light. Surface temperatures
of stars range from 3000 degrees Celsius to 50,000 degrees Celsius. When these surface
temperatures are plotted against luminosity, the stars fall into certain groups. Using data
similar to what you will plot in this activity, Danish astronomer Ejnar Hertzsprung and US
astronomer Henry Norris Russell independently arrived at similar results in what is now
commonly known as the HR Diagram.
Objective –
The objective of this activity is to plot a simple H-R Diagram and investigate how star
brightness, color, temperature, and star class are all related.
Materials –
Colored pencils (red, orange, yellow, dark blue, medium blue, light blue, orange)
Graph paper
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Procedure –
1. Study the star data chart below. Notice that stars absolute magnitude (a.k.a. real
brightness) vary greatly.
2. Get a piece of blank graph paper for the purpose of constructing your own HR
Diagram.
3. On the graph paper, you will be plotting spectral class on the X-axis and absolute
magnitude on the Y-axis (Mr. Spangler will show you how to set up this graph)
4. Using the star data table below, plot and label each star on your graph paper. As
you plot each star, do so using a small open circle in order to shade in your star the
appropriate color after you have plotted all 20.
STAR
1.
2.
3.
4.
5.
6.
7.
8.
9.
Sun
Sirius A
Sirius B
Canopus
Arcturus
Vega
Achernar
Rigel A
Rigel B
Absolute Magnitude
4.8
1.4
11.3
-5.5
-0.3
0.6
-2.8
-6.8
-0.4
Spectral Class
G2V
A1V
B8VII
F0II
K2III
A0V
B3V
B8I
B9V
10. Procyon A
2.7
F5V
11. Procyon B
13.0
F0VII
12. Proxima Centauri
15.0
M6V
13. Betelgeuse
-5.5
M2I
14. Aldebaran A
-0.6
K5III
15. Aldebaran B
12.0
M2V
16. Spica
-3.5
B21V
17. Pollux
1.1
K0III
18. Deneb
-7.0
A2I
19. Regulus A
-0.5
B7V
20. Bellatrix
-2.7
B2III
5. Shade in each star according to its color, represented by its spectral class, using
the following information. (20 points)
O – Dark Blue
(Temperature range – 30,000 to 60,000K)
B – Medium Blue
(Temperature range – 10,000 to 30,000K)
A – Light Blue
(Temperature range – 7,500 to 10,000K)
F – White
(Temperature range – 6,000 to 7,500K)
G – Yellow
(Temperature range – 5,000 to 6,000K)
K – Orange
(Temperature range – 3,500 to 5,000K)
M – Red
(Temperature range – less than 3,500K)
6. Label the following groups for each star on your HR Diagram: Supergiants, Giants
(include bright giants, giants, and subgiants), main-sequence, and white dwarfs
based on their roman numeral. (4 points)
I = Supergiants
II = Bright giants
III = Giants
IV = Subgiants
V = Main-Sequence
VI and VII = white dwarfs
7. Circle all Roman numeral I stars as a group (with one big circle) and name the group
Supergiants. Follow the same process for roman numerals II, III, and IV stars and
name the group Giants, for Roman numeral V name the group Main-Sequence, and
for roman numerals VI, VII name the group White Dwarfs. DO THIS IN PENCIL
8. Check with Mr. Spangler to see if the groups were done correctly (1 point for
check) ______
Analysis Questions (6 points)–
*Please answer these questions on a separate piece of paper
1. What is the general relationship between temperature and absolute magnitude
(star brightness)?
2. How does the absolute magnitude and temperature of the sun compare with those
of other stars?
3. List the colors from coolest to hottest.
4. Is there a relationship between mass and brightness? If so, state the relationship.
5. Dwarf stars are smaller than our Sun. How can they be so bright?
6. If a star is spectral class B, what is the range for its temperature? Color?
Part 4: A Stars’ Cycle of Life
Background – A star’s life cycle is determined by its mass. The larger the mass, the
shorter the life cycle. A star’s mass is determined by the amount of matter that is
available in its nebula, the giant cloud of gas and dust in which it is born. Over time, gravity
pulls the hydrogen gas in the nebula together and it begins to spin. As the gas spins faster
and faster, it heats up and is known as a protostar. Eventually the temperature reaches
15,000,000 C and nuclear fusion occurs in the cloud’s core. The cloud begins to glow
brightly. At this stage, it contracts a little and becomes stable. It is now called a main
sequence star and will remain in this stage, shining for millions or billions of years to come.
As the main sequence star glows, hydrogen in the core is converted into helium by nuclear
fusion. When the hydrogen supply in the core begins to run out, the core becomes unstable
and contracts. The outer shell of the star, which is still mostly hydrogen, starts to expand.
As it expands, it cools and glows red. The star has now reached the red giant phase. It is
red because it is cooler than it was in the main sequence star stage and it is a giant
because the outer shell has expanded outward. All stars evolve the same way up to the red
giant phase. The amount of mass a star has determines which of the following life cycle
paths it will take after the red giant phase.
Objective –
The objective of this activity is to demonstrate the life cycles of stars using balloons to
represent the different types of stars. This activity represents the different spectral
types with different color balloons.
Materials –
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4 balloons (red, white, yellow, blue)
Black marker
Red marker
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Scissors
Marble or bead
1” small Styrofoam ball
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1 tablespoon powder or confetti
Star Activity Cards
Procedure1. Setting up your balloons
a. For the yellow “star” (balloon) put a small Styrofoam ball inside the balloon
before blowing up
b. For the white “star” (balloon) put a marble or bead inside
c. For the blue “star” (balloon) put a large pinch of confetti inside
2. Modeling the 4 types of stars – Follow the directions on each activity card for Red,
Yellow, White, and Blue stars.
3. Make brief observations of the color of each star (red, blue, white, or yellow), what
solar mass they are, and what happens throughout the steps you do in the table
below (8 points). Observations could include how long they live, how they die, etc.
4. Each balloon represents a different type of stars, based on mass.
a. The Red balloon represents a low-mass star.
b. The Yellow balloon represents a medium-mass star, like our SUN.
c. The White balloon represents medium-high mass star.
d. The Blue balloon represents a high-mass star.
STAR
Solar Mass Observations
5. Before throwing away balloons, call Mr. Spangler over to see the finished products
for each one and discuss what happened. (1 point) _______
Analysis Questions (5 points)
*Please answer these questions on a separate piece of paper
1. Based on the four stars you just modeled, what was the common difference
among them that determined their fate? (Hint: one word)
2. Which star had the longest “wait” time? Why?
3. Which star lived the shortest “wait” time? Why
Part 5: Conclusion (5 points)
Write a solid paragraph (at least 5 sentences) about your conclusions from the
Stars’ Life Cycle section. Describe how you tested your hypothesis, the
experimental steps performed, and what you have learned as a result of this lab
experiment.
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Card 1 - Red Star
Step Number
0.4 Solar Mass
1
Star
Blow up the star to about 3”
2
5 million years
Wait, burning slowly and happily
until step 8
3
10 million years
Wait
4
500 million years
Wait
5
1 billion years
Wait
6
8 billion years
Wait
7
10 billion years
Wait
8
50 billion years
Blow up a little more
9
500 billion years
Let air out. Star has just slowly
shrunk and died. Color black.
Card 2 - Yellow Star
(Styrofoam ball included)
Step Number
1 Solar Mass
1
Star
Blow up the star to about 3”
2
5 million years
Wait
3
10 million years
Wait
4
500 million years
Wait (Watch planets being formed)
5
1 billion years
Blow up a little bit
6
8 billion years
Blow up more. Color star red. Sun
now becomes red super giant.
7
10 billion years
Blow up a little more.
Outer envelope
dissolves (slowly let out air). Use
scissors to cut balloon into pieces, keep
inside ball and remnants. You have
become a white dwarf surrounded by a
planetary nebula.
8
50 billion years
Move planetary nebula farther away.
9
500 billion years
Nebula is gone. Color white dwarf
black, it slowly dies out.
Card 3 White Star
(Marble or bead inside)
Step Number
10 Solar Masses
1
Star
Blow up the star to about 3”
2
5 million years
Hold and wait, you are still burning
3
10 million years
Blow up a “little” more.
4
500 million years
Slowly blow up some more. Star is
getting yellow/red as it becomes
bigger and cooler. Color it
yellow/red.
5
1 billion years
Blow up the star as fast and as
Much as you can. Do not disturb insides.
Wait. Teacher pops balloon.
6
8 billion years
You have exploded! Hold “neutron
star (marble or bead), throw
Super-nova remnants into space. Remain a
neutron
star almost forever.
7
10 billion years
Remain a neutron star.
8
50 billion years
Remain a neutron star.
9
500 billion years
Remain a neutron star.
Card 4 Blue Star
(powder or confetti)
Step Number
25 Solar Masses
1
Star
Blow up the star to about 3”
2
5 million years
Blow up star more.
3
10 million years
Blow up star as fast and as much
as you can. When you’ve blown it
up as much as possible, wait.
Teacher pops the balloon with a pin.
4
500 million years
Your star has exploded then shrunk
and has become a black hole.
Throw “super-nova remnants”
out into space.
Remain a black hole forever.
5
1 billion years
Remain a black hole forever.
6
8 billion years
Remain a black hole forever.
7
10 billion years
Remain a black hole forever.
8
50 billion years
Remain a black hole forever.
9
500 billion years
Remain a black hole forever.