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The Life and Death of Stars

Posted By: groovebeat

Date: 13 Jan 2014 22:56:50

For thousands of years, stars have been the prime example of something unattainable and unknowable—places so far away that we can learn almost nothing about them. Yet amazingly, astronomers have been able to discover exactly what stars are made of, how they are born, how they shine, how they die, and how they play a surprisingly direct role in our lives. Over the past century, this research has truly touched the stars, uncovering the essential nature of the beautiful panoply of twinkling lights that spans the night sky.

Consider these remarkable discoveries about the stars:

We are stardust: Every atom heavier than hydrogen and a few other light elements was forged at the heart of a star. The oxygen we breathe, the carbon in every cell of our bodies, and practically all other chemical elements are, in fact, stellar ashes.
Light fingerprints: Stars emit light across the entire range of the electromagnetic spectrum. Spectral lines and other features of starlight act like fingerprints to identify what a star is made of, its temperature, motion, and other properties.
Diamonds in the sky: Carbon is the end product of stars that are roughly the size of our sun. When such stars die, they shrink down to an unimaginably dense and inert ball of carbon atoms—a massive diamond in the sky called a white dwarf.
Space weather: Stars produce more than light and heat. Their outermost layer emits a steady stream of charged particles that constitutes a stellar wind. This wind can be strong enough to strip an atmosphere off a nearby planet.

No other large-scale object in the universe is as fundamental as a star. Galaxies are made of stars. Planets, asteroids, and comets are leftover debris from star formation. Nebulae are the remnants of dead stars and the seedbed for a new generation of stars. Even black holes, which are bizarre deformations of spacetime with infinite density, are a product of stars, typically created when a high-mass star ends its life in core collapse and a supernova explosion. And, of course, the sun is a star, without which we couldn’t exist.

Long ago, the magnificence of the star-filled sky and its clock-like motions inspired people to invent myths to explain this impressive feature of nature. Now we understand the stars at a much deeper level, not as legendary figures connected with constellations, but as engines of matter, energy, and the raw material of life itself. And thanks to powerful telescopes, our view of the stars is more stunning than ever.

The Life and Death of Stars introduces you to this spectacular story in 24 beautifully illustrated half-hour lectures that lead you through the essential ideas of astrophysics—the science of stars. Your guide is Professor Keivan G. Stassun of Vanderbilt University, an award-winning teacher and noted astrophysicist. Professor Stassun provides lively, eloquent, and authoritative explanations at a level suitable for science novices as well as for those who already know their way around the starry sky.

Understand Astronomy at a Fundamental Level

Stars are a central topic of astronomy, and because the study of stars encompasses key concepts in nuclear physics, electromagnetism, chemistry, and other disciplines, it is an ideal introduction to how we understand the universe at the smallest and largest scales. Indeed, today’s most important mysteries about the origin and fate of the universe are closely connected to the behavior of stars. For example, the accelerating expansion of the universe due to a mysterious dark energy was discovered thanks to a special type of supernova explosion that serves as an accurate distance marker across the universe. And another enigma, dark matter, may have played a crucial role in the formation of the earliest stars.

Using dazzling images from instruments such as the Hubble Space Telescope, along with informative graphics and computer animations, The Life and Death of Stars takes you to some otherworldly destinations, including these:

Stellar nurseries: Stars form inside vast clouds of interstellar gas and dust, where every phase of stellar growth can often be seen. Take a virtual fly-through of the Orion Nebula, witnessing the dynamism of stellar creation and the immensity of the regions where stars are born.
Planetary nebulae: Mislabeled “planetary” because they were originally thought to involve planets, these slowly expanding shells of glowing gas are the last outbursts of dying stars. They vary widely in shape and color and are among the most beautiful of celestial sights.
Core of the sun: We can’t see into the sun, but sunquakes and other clues reveal the extreme conditions at its center, 400,000 miles below the visible surface. Make an imaginary trip there, viewing the layers that transfer heat from the 15-million-degree Celsius cauldron at the sun’s core.
Protoplanetary systems: Planets form inside disks of gas and dust surrounding young stars. See how newborn planets jockey for position close to their parent stars and how some planets are ejected from the system—a fate that may have befallen planets orbiting our own sun.

Reach for the Stars

Just as fascinating as the places you visit are the observational techniques you learn about. One of Professor Stassun’s research areas is exoplanetary systems—planets orbiting other stars. You investigate the different methods astronomers use to detect inconspicuous, lightless planets lost in the glare of brilliant stars, seen from many light-years away. You also explore the principles of telescopes and light detectors, and you learn about the vast range of the electromagnetic spectrum, the largest part of which is invisible to human eyes—but not to our instruments.

An astronomer’s other tools for understanding stars include the invaluable Hertzsprung-Russell diagram, which tells the complete story of stellar evolution in one information-rich graphic. You compare the sun’s position on this chart with the entire range of other star types that have varying masses, temperatures, and colors.

You also become familiar with the periodic table of elements, discovering how fusion reactions inside stars forge successively heavier atoms, producing some in abundance, temporarily skipping others, and creating everything heavier than iron in the cataclysmic blast of a supernova. Nickel, copper, gold, and scores of other elements important to humans thus owe their existence to the most energetically powerful phenomenon in the cosmos. You see, too, how astronomers use computer models to analyze the rapid sequence of events that leads to a supernova.

“Hitch your wagon to a star,” advised Ralph Waldo Emerson. In other words, reach for the stars! The Life and Death of Stars is your guide to this lofty goal.

24 Lectures

01 Why the Stellar Life Cycle Matters
02 The Stars’ Information Messenger
03 Measuring the Stars with Light
04 Stellar Nurseries
05 Gravitational Collapse and Protostars
06 The Dynamics of Star Formation
07 Solar Systems in the Making
08 Telescopes—Our Eyes on the Stars
09 Mass—The DNA of Stars
10 Eclipses of Stars—Truth in the Shadows
11 Stellar Families
12 A Portrait of Our Star, the Sun
13 E = mc2—Energy for a Star’s Life
14 Stars in Middle Age
15 Stellar Death
16 Stellar Corpses—Diamonds in the Sky
17 Dying Breaths—Cepheids and Supernovae
18 Supernova Remnants and Galactic Geysers
19 Stillborn Stars
20 The Dark Mystery of the First Stars
21 Stars as Magnets
22 Solar Storms—The Perils of Life with a Star
23 The Stellar Recipe of Life
24 A Tale of Two Stars