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Supernova Chemistry |
Objective
Students will observe visible spectra of known elements and identify an
unknown element or combination of elements by visible spectra.
Grade level
Grades 9 - 12
Subjects
Astronomy, Chemistry, and Physics
Prerequisites
Math
Students should be proficient in Algebra, especially in the areas of
pattern recognition and the metric system of measurement.
Science
Students should have had an introduction to the electromagnetic spectrum, the
concepts of wavelength, frequency, and quantization of energy. Students should
be proficient at making observations, making measurements, discovering
patterns, and drawing conclusions from those observations, measurements, and
patterns.
Engagement
Students view the slide presentation "The Sky at Many
Wavelengths" and write at least five questions about the ideas presented
in this slide show. The slide set can be ordered from:
Society of the Pacific at:
Astronomical Society of the Pacific (ASP)
390 Ashton Avenue
San Francisco CA 94112
Phone: 415-337-1100
For Orders: 1-800-335-2624
E-mail: catalog@aspsky.org
URL: http://www.aspsky.org/
Alternatively, students can view the High-Energy Astrophysics Learning
Center's
Multiwavelength Astronomy page on the Crab Nebula.
The teacher should ask each group of students to share two or three of
their questions with the rest of the class.
Materials
- 10 spectroscopes (Science Kit 45492 or 16525)
- 5 spectrum tubes (Science Kit 62999-01 -62999-55)
(one of these should be mercury)
- 1 incandescent light bulb
- 1 "plant grow" light bulb
- 1 Compact Fluorescent light fixture
- 4 Chemical Light Sticks (each lasts four hours)
- 1 Standard Fluorescent light tube
- 5 Spectrum tube power supplies
(Science Kit 62999 26)
- 10 Packages of colored pencils
Science Kit (http://www.sciencekit.com/) is a leading
supplier of science materials and equipment to science teachers
throughout the U.S. Ordering information is available via their
website.
Introduction
Electromagnetic radiation is characterized by
its wavelength, frequency, and intensity. These
measurable quantities can be used to determine the
temperature, density, and composition of the matter
that emits the radiation. These measurable
quantities can also be used to understand the
events which trigger the release of the radiation.
When Isaac Newton passed a beam of sunlight through
a prism in 1666, a continuous spectrum of light
was seen. Light began to reveal its secrets, and a
special window of understanding was opened for the
first time. Analysis of this kind of information
gives scientists a window to study the atom and the
stars. This window is called spectroscopy.
During the nineteenth century, experimenters
found that the dark lines in the Sun's spectrum and
the bright lines in the spectra of incandescent
gases in the laboratory matched. The window opened
a little wider. During the early twentieth century
useful models of the atom emerged which are still
used to explain the special signature of spectral
lines each element emits when heated or energized
by electrical discharge. As our window inside the
atom widened so did our ability to analyze all
types of radiation emitted by stellar objects.
Detection devices have become steadily more
sophisticated giving us more information about
objects which are not even visible with the best
telescopes on Earth.
X-ray measurements provide the most direct probes of astrophysical
environments with temperatures exceeding one million degrees Kelvin. Such
temperatures are encountered frequently in the cosmos... in supernovae, binary
accretion,
stellar coronae, and so on. Here, we are interested in what X-ray
spectroscopy can tell us about supernova explosions.
Supernova explosions are believed to be the primary mechanism for the
production and dispersal of heavy elements into the
interstellar medium
(ISM). They are also believed to be the origin of cosmic rays. The quest
to understand these processes has driven the development of X-ray
spectroscopy.
The X-ray spectrum of a supernova contains lines emitted from the
non-equilibrium, shocked gas sent out into space by the explosion. Examining
the intensity and width of a line, the relative appearance of resonance,
intercombination, and forbidden lines from a given element, and the
underlying continuum energy... all of these things give us insight into the
extreme conditions resulting from a supernova explosion. They can lead us to
an understanding of where all of the heavy elements in our Universe came
from, and how they got to be where they are now.
Time
1 day for engagement and pre-lab discussion,
1 day for data collection, and 1 day for
post-lab discussion or writing of a lab
report.
ACKNOWLEDGMENTS
This experiment was adapted from "Spectroscopy
Lab", Chemistry Laboratory Manual, Prentice Hall, 1996, pp. 61-66.
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