Name:______________________________________________________ Stellar Spectra Lab
Objective: Students will be able to examine the characteristics of stellar spectra as well as burning elements to try
and predict the elements burning in distant stars as well as elemental candles.
Part I: Star Videos
Part II: Types of Spectra
Materials:
fluorescent light
incandescent light
sunlight spectroscope
Background Information:
A spectrum is the most important tools an astronomer uses. In a spectrum, the components of radiation are
arranged progressively in terms of wavelength or frequency. The spectrum of each celestial object contains
information on the chemical composition of that object. A rainbow is the most spectacular natural spectrum we can
see everywhere. It occurs when sunlight falls on a raindrop and is refracted, splitting the white light into its
composite colors. A group of spectrums is called a spectra
Three kinds of spectrum from matter are:
1. Continuous Spectrum: A continuous spectrum is formed by an object, which is solid or liquid in nature
and heated to the point of incandescence. There are no lines in a continuous spectrum.
2. An emission spectrum is formed when a gas is heated to the point of incandescence. An emission
spectrum contains bright lines against a dark background. In an emission spectrum the lines appear
brighter as energy is absorbed and subsequently emitted by the gas molecules.
3. An absorption spectrum occurs when the light produced by an object, which is in a solid, liquid or gaseous
state, passes through a gaseous medium that is not in a state of incandescence. Such a spectrum contains
dark lines. Here the wavelength of radiation corresponding to the gas molecules in that medium is
absorbed. These missing wavelengths appear as dark lines in the spectrum.
Each element in the periodic table can appear in gaseous form and will produce a series of bright lines unique
to that element. Hydrogen will not look like helium which will not look like carbon which will not look like iron...
and so on. Thus, astronomers can identify what kinds of stuff are in stars from the lines they find in the star's
spectrum. This type of study is called spectroscopy
Procedure:
1. Students are to travel around the darkened room, using their flashlights as a guide. Student are to observe
EACH of the different light sources. Then, with each light source, students are to color what they see as
well as identify the different type of spectrum that is being observed.
a. Candle light:
i. Color the spectrum observed:
ii. What type of spectrum do you believe is being represented?
b. Backlight:
i. Color the spectrum observed:
ii. What type of spectrum do you believe is being represented?
c. Incandescent Light:
i. Color the spectrum observed:
ii. What type of spectrum do you believe is being represented?
d. Fluorescent light:
i. Color the spectrum observed:
ii. What type of spectrum do you believe is being represented?
Part III: Candle Spectra
Procedure:
1. Within the darkened classroom, students are to observe each of the candle flames with the spectroscope.
2. Place the candle in the aluminum try, using the clay to hold the candle upright. Light the candle, then WET
the match before placing in the trash.
3. First, students are then to identify the colors seen and color the patterns in the specific regions below.
4. Then, students are to use the spectra lines that are provided to TRY and determine the element that is
burning within the candle that provides that specific color and spectra.
Common Emission Spectra
5.
For each color of candle, draw and COLOR the EMISSION SPECTRA that you observe. You very closely and
speak with your group as to the colors they observe to make you BEST hypothesis.
6. Complete the Date Table Below:
Candle Color
Lis the colors of lines that
are observed:
Color your Emission Spectrum as accurately as
possible:
Hypothesis as
to element
present:
Purple
Blue
Yellow/Orange
Green
Red
Going over together:
After looking over the power point of the candle composition, what was the ACTUAL element that was
within each candle?
Were you correct; yes or no?
Purple:________________________________________________
__________________
Blue:___________________________________________________
__________________
Yellow:________________________________________________
__________________
Green:_________________________________________________
__________________
Red:___________________________________________________
__________________
Part IV: Understanding Star Spectra
Procedure:
1.
Use the listed elements below to determine the elements that are in the mystery stubstance below.
List the elements present in the Spectrum of Unknown Composition below. (Look Carefully- HINT It helps to line-up
the spectral lines with a ruler)
Elements present:
Part IV: The Sun’s Spectra
Now for the REAL CHALLENEGE! Can you identify the
Analysis and Conclusion Questions:
1.
Identify THREE things scientists can learn by observing an objects spectra.
2. You have a new summer job as a Firework Performer. You job is to create an elaborate firework display for
your town and the theme this year is “Outer Space”. DRAW (something in space!) and COLOR each firework
design below. Then, list what each firework is going to represent the COLORS of the display as well as the
ELEMENTS that you will be putting in the fireworks to create each elaborate display!
Draw Display #1:
Colors:__________________________________
Elements needed:__________________________________________________
Draw Display #2
Colors:__________________________________
Elements needed:__________________________________________________
Draw Display #3
Colors:__________________________________
Elements needed:__________________________________________________
Use the diagram below to answer the following questions:
3.
What do the stars of Orion’s Stars, Rigel, and Sirius have in common?
4. Based on the data above, what type of star is Betelgeuse?
5. In comparison to Betelgeuse, what type of star is Arcturus?
6. Rigel is a white dwarf. Based on the questions above and this known information, how will the Sun’s
elemental composition change as it ages?
7. Overall, how does the level of hydrogen change as a star gets older?