Download Stellar Explosions

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Visions of the Universe
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~ Four Centuries of Discovery
Stellar
Explosions
supplemental materials
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Stellar Explosions
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Table of Contents
Exhibit Overview � � � � � � � � � � � � � � � � � � � � � � � � 3
Science Background � � � � � � � � � � � � � � � � � � � � 4
Science Misconceptions� � � � � � � � � � � � � � � � 6
Glossary� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 7
Related Educational Resources� � � � � � 9
Exhibit Overview
I
n turning his telescope to the heavens in 1609, Galileo embarked upon a journey
that would revolutionize science and culture alike, profoundly changing our
view of our place in the universe. Our views of the universe, and how they have
evolved over time, are portrayed in the images and text of the “Visions of the
Universe: Four Centuries of Discovery” exhibit.
In recognition of the International Year of Astronomy, this exhibit includes six twosided panels that feature key astronomical discoveries from the past 400 years. The
exhibit also highlights the technological advancements that made these discoveries
possible. Exhibit topics range from celestial objects within our own “cosmic
backyard” to those beyond the realm of our solar system. Featured objects include
the Sun, the Moon, Saturn, Mars, comets, stars, nebulae, and galaxies. Images are
accompanied by captions that highlight relevant, historical discoveries.
The “Visions of the Universe: Four Centuries of Discovery” exhibit is supported
by supplemental resource documents available online, in PDF format, for each
panel. These twelve documents include science background information in the
form of Q&As, related science misconceptions, a glossary, and links to additional
resources on NASA’s Amazing Space Web site. In addition, each exhibit panel is
available as a downloadable, poster-size file. These materials are available from:
http://amazing-space.stsci.edu/visions
The “Visions of the Universe: Four Centuries of Discovery” exhibit was produced
in December 2008 by the Space Telescope Science Institute, the American Library
Association, and the Smithsonian Astrophysical Observatory, through funding
from the National Aeronautics and Space Administration. •
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Science Background
NOTE: Words in boldface italics are defined in the glossary.
Q1:
Who was Johannes Kepler?
ANSWER:
Johannes Kepler (1571–1630) was a German mathematician, astronomer, astrologer, and key figure in the
17th century astronomical revolution. Kepler is most famous for his three laws of planetary motion, which
explained and predicted the positions of the planets much better than previous ideas. His work was a key
component in establishing that the Sun, not Earth, was at the center of the solar system.
Q2:
Who found the 1885 nova in Andromeda?
ANSWER:
The 1885 nova-like outburst in Andromeda was discovered on August 20, 1885 by Ernst Hartwig (1851–1923),
working at Dorpat (Tartu) Observatory in Estonia. It was bright enough to outshine the entire nucleus of the
galaxy. It faded by February 1890, in a manner much like a nova.
Q3:
What were the unusual properties of the nova in Andromeda?
ANSWER:
The star was reported to be reddish in color and declined very rapidly in brightness like most novae. In 1917,
however, George W. Ritchey measured the distance to the Andromeda Galaxy and discovered it lay much farther
than had previously been thought. This meant that the nova in Andromeda released a much greater amount of
energy than was typical for a nova. This object was designated as supernova “S Andromedae.”
Q4:
Who was Fred Hoyle?
ANSWER:
Fred Hoyle (1915–2001) was an English astronomer who worked on the problem of how the various observed
elements in the universe were produced. He figured out that a supernova is the explosion of a star that disperses
the star’s elements across space.
Continued …
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Science Background, continued …
Q5:
What was the significance of elements spreading across space?
ANSWER:
Shortly after the Big Bang, the universe was composed mostly of hydrogen with some helium. The question
is how did the other elements form? The idea of nuclear fusion forming all the elements up to that of iron
works, but it cannot account for the elements heavier than iron. During the supernova explosion of a star,
abundant energy is available to produce elements heavier than iron. A supernova also spreads these elements
across interstellar space, where they become part of other gas clouds. If those gas clouds collapse to form stars,
some of those elements become parts of planets. All the heavy elements on our planet Earth were created in
stars and spread across space by supernova explosions and stellar winds.
Q6:
What are NASA’s Great Observatories?
ANSWER:
NASA’s four Great Observatories are a series of space telescopes meant to give the most complete picture of
objects across many different wavelengths. Each observatory studies a particular wavelength region in great
detail. The telescopes, in order of launch, are: the Hubble Space Telescope (1990, detects visible light and
some infrared and ultraviolet light), Compton Gamma Ray Observatory (1991, detected gamma rays),
Chandra X-ray Observatory (1999, detects X-rays), and Spitzer Space Telescope (2003, detects infrared light).
All except for the Compton telescope are operational.
Q7:
Where was Supernova 1987A found?
ANSWER:
Supernova 1987A was found in a nearby dwarf galaxy called the Large Magellanic Cloud, visible in the
southern sky. More specifically, the supernova was located on the outskirts of the Tarantula Nebula. It was
discovered on February 24, 1987, by Ian Shelton and Oscar Duhalde at the Las Campanas Observatory in
Chile, and independently by Albert Jones in New Zealand and Colin Henshaw in Zimbabwe.
Q8:
What can astronomers learn about supernovae and their remnants from multiwavelength studies of supernova remnants?
ANSWER:
Supernova explosions are very energetic events. By studying supernovae and their remnants in multiwavelengths, astronomers gain a clearer picture of the death of massive stars and their effect on the gas and
dust of the interstellar medium surrounding them. The supernova blasts from massive stars can sweep up the
surrounding medium into expanding shells filled with hot gas. The structure and composition of the shells
reveal the make-up of the star and the elements produced during the explosion. The expanding shells can in
turn produce conditions that may start a new wave of star births. •
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Science Misconceptions
MYTH 1:
All stars are exactly the same.
FACT: All stars are not the same. Stars vary in brightness, color, mass, temperature, and age.
MYTH 2:
Stars live forever.
FACT: Stars do not live forever. Stars’ lifespans range from millions to trillions of years, depending on
the type of star. The shortest-lived stars last about 50 million years.
MYTH 3:
All stars will end their lives the same way — as supernovae.
FACT: Not all stars will end their lives in violent explosions, called supernovae. Only massive stars become
supernovae. The Sun and other less-massive stars will gently puff off their outer layers to form shells of
glowing gas called planetary nebulae. •
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Glossary
Andromeda Galaxy
A spiral galaxy approximately 2.5 million light-years away in the constellation Andromeda. It is the
nearest spiral galaxy to our Milky Way Galaxy. It is also known as Messier 31, M31, and NGC 224. It
was originally known as the Andromeda Nebula.
Big Bang
A broadly accepted theory for the origin and evolution of our universe. The theory says that the
observable universe started roughly 13.7 billion years ago from an extremely dense and incredibly hot
initial state.
Fusion
A nuclear process that releases energy when light atomic nuclei combine to form heavier nuclei. Fusion
is the energy source for all stars, including our Sun.
Gamma rays
The part of the electromagnetic spectrum with the highest energy; also called gamma radiation. Gamma
rays can cause serious damage when absorbed by living cells.
Infrared light
A region of the electromagnetic spectrum not visible to the human eye. This region of light that cannot
be seen is similar to the range of sounds that are too low for the human ear to hear. Infrared light can be
detected as the heat from a fire or a light bulb.
Interstellar space
The dark regions of space located between stars.
Laws of planetary motion
Three laws, derived by 17th century German astronomer Johannes Kepler, that describe planetary motion.
Continued …
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Glossary, continued …
NASA’s Great Observatories
NASA’s four Great Observatories are a series of space telescopes meant to give the most complete picture
of objects across many different wavelengths. Each observatory studies a particular wavelength region in
great detail.
Nova (pl., novae)
A star that suddenly brightens. This usually occurs in a binary star system (consisting of a white dwarf
and a companion star) that rapidly brightens and then slowly fades back to normal.
Supernova (pl., supernovae)
The explosive death of a star whose energy output causes its expanding gases to glow brightly for weeks
or months. A supernova remnant is the glowing, expanding gaseous remains of a supernova explosion.
Supernova remnant
The glowing, expanding gaseous remains of a supernova explosion.
Ultraviolet light
The part of the electromagnetic spectrum that has slightly higher energy than visible light, but is not
visible to the human eye. Just as there are high-pitched sounds that cannot be heard, there is high-energy
light that cannot be seen. Too much exposure to ultraviolet light causes sunburns.
Visible light
The part of the electromagnetic spectrum that human eyes can detect; also known as the visible spectrum.
The colors of the rainbow make up visible light. Blue light has more energy than red light.
X-rays
The part of the electromagnetic spectrum with energy between ultraviolet light and gamma rays. X-rays
are considered high-energy radiation and are used in medicine to detect broken bones and cavities in
teeth. Astronomers can detect X-rays from exploding stars and black holes. •
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Related Educational Resources
from NASA's “Amazing Space” Web site
http://amazing-space.stsci.edu
“Amazing Space” uses the Hubble Space Telescope’s discoveries to inspire and educate about the wonders of our
universe. The Amazing Space Web site includes curriculum support tools, a section for the general public, and a
special section for educators and developers. The curriculum support tools are developed by a team of scientists,
education specialists, and multimedia experts. They are aligned with national educational standards and are
reviewed for scientific accuracy. Find teaching tools, graphic organizers, Online Explorations, and more.
Online Explorations
“Online Explorations” are fun, interactive activities for exploring various space science topics.
• Telescopes From the Ground Up
“Telescopes From the Ground Up” traces the 400 years of telescope development from Galileo’s refractor
to NASA’s Great Observatories. The overview for this activity can be found at:
http://amazing-space.stsci.edu/eds/overviews/explorations/telehistory.php
Specific sections of “Telescopes From the Ground Up” related to this exhibit panel include:
“Era of Early Refractors,” which describes Kepler’s contribution to telescope development.
http://amazing-space.stsci.edu/resources/explorations/groundup/lesson/eras/early-refractors/
index.php
“Era of Multi-mirror Telescopes: Multiple Mirror Telescope,” which describes the telescope
astronomers used to discover that gamma-ray bursts are associated with supernova explosions.
http://amazing-space.stsci.edu/resources/explorations/groundup/lesson/scopes/mmt/index.php
Reading Selections
These selections are grade-appropriate readings based on Hubble press releases. “Star Witness News” stories
are written for grades 5–8. “Tales of…” stories are written for grades 9–12.
Tales of …
“A history of the Crab Nebula,” which describes the formation of the Crab Nebula from a supernova
that was first observed in 1054, and the subsequent discovery of a pulsar (a neutron star) at the center
of the nebula.
http://amazing-space.stsci.edu/resources/tales/crab.php
“Key events in the history of Supernova 1987A,” which presents a timeline of the discovery and
subsequent observations of the nearest supernova in 400 years.
http://amazing-space.stsci.edu/resources/tales/1987a.php
Continued …
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Educational Resources, continued …
Lithographs
These are Hubble Space Telescope images of celestial objects that include informational text and inquirybased classroom activities.
Crab Nebula (M1)
This lithograph shows the remains of a star that exploded as a supernova nearly a thousand years ago.
http://amazing-space.stsci.edu/eds/overviews/print/lithos/crab.php
Fast Facts
This is a collection of tables that provide vital statistics for the planets and other celestial objects.
Crab Nebula
This table lists the name, description, location, size, and distance of the nebula from Earth.
http://amazing-space.stsci.edu/eds/overviews/fastfacts/crab_nebula.php
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