Chapter 13: Star Birth and Death
Chapter 1
How Science Works
- The Scientific Method
- Evidence
- Measurements
- Units and the Metric System
- Measurement Errors
- Estimation
- Dimensions
- Mass, Length, and Time
- Observations and Uncertainty
- Precision and Significant Figures
- Errors and Statistics
- Scientific Notation
- Ways of Representing Data
- Logic
- Mathematics
- Geometry
- Algebra
- Logarithms
- Testing a Hypothesis
- Case Study of Life on Mars
- Theories
- Systems of Knowledge
- The Culture of Science
- Computer Simulations
- Modern Scientific Research
- The Scope of Astronomy
- Astronomy as a Science
- A Scale Model of Space
- A Scale Model of Time
- Questions
Chapter 2
Early Astronomy
- The Night Sky
- Motions in the Sky
- Navigation
- Constellations and Seasons
- Cause of the Seasons
- The Magnitude System
- Angular Size and Linear Size
- Phases of the Moon
- Eclipses
- Auroras
- Dividing Time
- Solar and Lunar Calendars
- History of Astronomy
- Stonehenge
- Ancient Observatories
- Counting and Measurement
- Astrology
- Greek Astronomy
- Aristotle and Geocentric Cosmology
- Aristarchus and Heliocentric Cosmology
- The Dark Ages
- Arab Astronomy
- Indian Astronomy
- Chinese Astronomy
- Mayan Astronomy
- Questions
Chapter 3
The Copernican Revolution
- Ptolemy and the Geocentric Model
- The Renaissance
- Copernicus and the Heliocentric Model
- Tycho Brahe
- Johannes Kepler
- Elliptical Orbits
- Kepler's Laws
- Galileo Galilei
- The Trial of Galileo
- Isaac Newton
- Newton's Law of Gravity
- The Plurality of Worlds
- The Birth of Modern Science
- Layout of the Solar System
- Scale of the Solar System
- The Idea of Space Exploration
- Orbits
- History of Space Exploration
- Moon Landings
- International Space Station
- Manned versus Robotic Missions
- Commercial Space Flight
- Future of Space Exploration
- Living in Space
- Moon, Mars, and Beyond
- Societies in Space
- Questions
Chapter 4
Matter and Energy in the Universe
- Matter and Energy
- Rutherford and Atomic Structure
- Early Greek Physics
- Dalton and Atoms
- The Periodic Table
- Structure of the Atom
- Energy
- Heat and Temperature
- Potential and Kinetic Energy
- Conservation of Energy
- Velocity of Gas Particles
- States of Matter
- Thermodynamics
- Entropy
- Laws of Thermodynamics
- Heat Transfer
- Thermal Radiation
- Wien's Law
- Radiation from Planets and Stars
- Internal Heat in Planets and Stars
- Periodic Processes
- Random Processes
- Questions
Chapter 5
The Earth-Moon System
- Earth and Moon
- Early Estimates of Earth's Age
- How the Earth Cooled
- Ages Using Radioactivity
- Radioactive Half-Life
- Ages of the Earth and Moon
- Geological Activity
- Internal Structure of the Earth and Moon
- Basic Rock Types
- Layers of the Earth and Moon
- Origin of Water on Earth
- The Evolving Earth
- Plate Tectonics
- Volcanoes
- Geological Processes
- Impact Craters
- The Geological Timescale
- Mass Extinctions
- Evolution and the Cosmic Environment
- Earth's Atmosphere and Oceans
- Weather Circulation
- Environmental Change on Earth
- The Earth-Moon System
- Geological History of the Moon
- Tidal Forces
- Effects of Tidal Forces
- Historical Studies of the Moon
- Lunar Surface
- Ice on the Moon
- Origin of the Moon
- Humans on the Moon
- Questions
Chapter 6
The Terrestrial Planets
- Studying Other Planets
- The Planets
- The Terrestrial Planets
- Mercury
- Mercury's Orbit
- Mercury's Surface
- Venus
- Volcanism on Venus
- Venus and the Greenhouse Effect
- Tectonics on Venus
- Exploring Venus
- Mars in Myth and Legend
- Early Studies of Mars
- Mars Close-Up
- Modern Views of Mars
- Missions to Mars
- Geology of Mars
- Water on Mars
- Polar Caps of Mars
- Climate Change on Mars
- Terraforming Mars
- Life on Mars
- The Moons of Mars
- Martian Meteorites
- Comparative Planetology
- Incidence of Craters
- Counting Craters
- Counting Statistics
- Internal Heat and Geological Activity
- Magnetic Fields of the Terrestrial Planets
- Mountains and Rifts
- Radar Studies of Planetary Surfaces
- Laser Ranging and Altimetry
- Gravity and Atmospheres
- Normal Atmospheric Composition
- The Significance of Oxygen
- Questions
Chapter 7
The Giant Planets and Their Moons
- The Gas Giant Planets
- Atmospheres of the Gas Giant Planets
- Clouds and Weather on Gas Giant Planets
- Internal Structure of the Gas Giant Planets
- Thermal Radiation from Gas Giant Planets
- Life on Gas Giant Planets?
- Why Giant Planets are Giant
- Gas Laws
- Ring Systems of the Giant Planets
- Structure Within Ring Systems
- The Origin of Ring Particles
- The Roche Limit
- Resonance and Harmonics
- Tidal Forces in the Solar System
- Moons of Gas Giant Planets
- Geology of Large Moons
- The Voyager Missions
- Jupiter
- Jupiter's Galilean Moons
- Jupiter's Ganymede
- Jupiter's Europa
- Jupiter's Callisto
- Jupiter's Io
- Volcanoes on Io
- Saturn
- Cassini Mission to Saturn
- Saturn's Titan
- Saturn's Enceladus
- Discovery of Uranus and Neptune
- Uranus
- Uranus' Miranda
- Neptune
- Neptune's Triton
- Pluto
- The Discovery of Pluto
- Pluto as a Dwarf Planet
- Dwarf Planets
- Questions
Chapter 8
Interplanetary Bodies
- Interplanetary Bodies
- Comets
- Early Observations of Comets
- Structure of the Comet Nucleus
- Comet Chemistry
- Oort Cloud and Kuiper Belt
- Kuiper Belt
- Comet Orbits
- Life Story of Comets
- The Largest Kuiper Belt Objects
- Meteors and Meteor Showers
- Gravitational Perturbations
- Asteroids
- Surveys for Earth Crossing Asteroids
- Asteroid Shapes
- Composition of Asteroids
- Introduction to Meteorites
- Origin of Meteorites
- Types of Meteorites
- The Tunguska Event
- The Threat from Space
- Probability and Impacts
- Impact on Jupiter
- Interplanetary Opportunity
- Questions
Chapter 9
Planet Formation and Exoplanets
- Formation of the Solar System
- Early History of the Solar System
- Conservation of Angular Momentum
- Angular Momentum in a Collapsing Cloud
- Helmholtz Contraction
- Safronov and Planet Formation
- Collapse of the Solar Nebula
- Why the Solar System Collapsed
- From Planetesimals to Planets
- Accretion and Solar System Bodies
- Differentiation
- Planetary Magnetic Fields
- The Origin of Satellites
- Solar System Debris and Formation
- Gradual Evolution and a Few Catastrophies
- Chaos and Determinism
- Extrasolar Planets
- Discoveries of Exoplanets
- Doppler Detection of Exoplanets
- Transit Detection of Exoplanets
- The Kepler Mission
- Direct Detection of Exoplanets
- Properties of Exoplanets
- Implications of Exoplanet Surveys
- Future Detection of Exoplanets
- Questions
Chapter 10
Detecting Radiation from Space
- Observing the Universe
- Radiation and the Universe
- The Nature of Light
- The Electromagnetic Spectrum
- Properties of Waves
- Waves and Particles
- How Radiation Travels
- Properties of Electromagnetic Radiation
- The Doppler Effect
- Invisible Radiation
- Thermal Spectra
- The Quantum Theory
- The Uncertainty Principle
- Spectral Lines
- Emission Lines and Bands
- Absorption and Emission Spectra
- Kirchoff's Laws
- Astronomical Detection of Radiation
- The Telescope
- Optical Telescopes
- Optical Detectors
- Adaptive Optics
- Image Processing
- Digital Information
- Radio Telescopes
- Telescopes in Space
- Hubble Space Telescope
- Interferometry
- Collecting Area and Resolution
- Frontier Observatories
- Questions
Chapter 11
Our Sun: The Nearest Star
- The Sun
- The Nearest Star
- Properties of the Sun
- Kelvin and the Sun's Age
- The Sun's Composition
- Energy From Atomic Nuclei
- Mass-Energy Conversion
- Examples of Mass-Energy Conversion
- Energy From Nuclear Fission
- Energy From Nuclear Fusion
- Nuclear Reactions in the Sun
- The Sun's Interior
- Energy Flow in the Sun
- Collisions and Opacity
- Solar Neutrinos
- Solar Oscillations
- The Sun's Atmosphere
- Solar Chromosphere and Corona
- Sunspots
- The Solar Cycle
- The Solar Wind
- Effects of the Sun on the Earth
- Cosmic Energy Sources
- Questions
Chapter 12
Properties of Stars
- Stars
- Star Names
- Star Properties
- The Distance to Stars
- Apparent Brightness
- Absolute Brightness
- Measuring Star Distances
- Stellar Parallax
- Spectra of Stars
- Spectral Classification
- Temperature and Spectral Class
- Stellar Composition
- Stellar Motion
- Stellar Luminosity
- The Size of Stars
- Stefan-Boltzmann Law
- Stellar Mass
- Hydrostatic Equilibrium
- Stellar Classification
- The Hertzsprung-Russell Diagram
- Volume and Brightness Selected Samples
- Stars of Different Sizes
- Understanding the Main Sequence
- Stellar Structure
- Stellar Evolution
- Questions
Chapter 14
The Milky Way
- The Distribution of Stars in Space
- Stellar Companions
- Binary Star Systems
- Binary and Multiple Stars
- Mass Transfer in Binaries
- Binaries and Stellar Mass
- Nova and Supernova
- Exotic Binary Systems
- Gamma Ray Bursts
- How Multiple Stars Form
- Environments of Stars
- The Interstellar Medium
- Effects of Interstellar Material on Starlight
- Structure of the Interstellar Medium
- Dust Extinction and Reddening
- Groups of Stars
- Open Star Clusters
- Globular Star Clusters
- Distances to Groups of Stars
- Ages of Groups of Stars
- Layout of the Milky Way
- William Herschel
- Isotropy and Anisotropy
- Mapping the Milky Way
- Questions
Chapter 15
Galaxies
- The Milky Way Galaxy
- Mapping the Galaxy Disk
- Spiral Structure in Galaxies
- Mass of the Milky Way
- Dark Matter in the Milky Way
- Galaxy Mass
- The Galactic Center
- Black Hole in the Galactic Center
- Stellar Populations
- Formation of the Milky Way
- Galaxies
- The Shapley-Curtis Debate
- Edwin Hubble
- Distances to Galaxies
- Classifying Galaxies
- Spiral Galaxies
- Elliptical Galaxies
- Lenticular Galaxies
- Dwarf and Irregular Galaxies
- Overview of Galaxy Structures
- The Local Group
- Light Travel Time
- Galaxy Size and Luminosity
- Mass to Light Ratios
- Dark Matter in Galaxies
- Gravity of Many Bodies
- Galaxy Evolution
- Galaxy Interactions
- Galaxy Formation
- Questions
Chapter 16
The Expanding Universe
- Galaxy Redshifts
- The Expanding Universe
- Cosmological Redshifts
- The Hubble Relation
- Relating Redshift and Distance
- Galaxy Distance Indicators
- Size and Age of the Universe
- The Hubble Constant
- Large Scale Structure
- Galaxy Clustering
- Clusters of Galaxies
- Overview of Large Scale Structure
- Dark Matter on the Largest Scales
- The Most Distant Galaxies
- Black Holes in Nearby Galaxies
- Active Galaxies
- Radio Galaxies
- The Discovery of Quasars
- Quasars
- Types of Gravitational Lensing
- Properties of Quasars
- The Quasar Power Source
- Quasars as Probes of the Universe
- Star Formation History of the Universe
- Expansion History of the Universe
- Questions
Chapter 17
Cosmology
- Cosmology
- Early Cosmologies
- Relativity and Cosmology
- The Big Bang Model
- The Cosmological Principle
- Universal Expansion
- Cosmic Nucleosynthesis
- Cosmic Microwave Background Radiation
- Discovery of the Microwave Background Radiation
- Measuring Space Curvature
- Cosmic Evolution
- Evolution of Structure
- Mean Cosmic Density
- Critical Density
- Dark Matter and Dark Energy
- Age of the Universe
- Precision Cosmology
- The Future of the Contents of the Universe
- Fate of the Universe
- Alternatives to the Big Bang Model
- Space-Time
- Particles and Radiation
- The Very Early Universe
- Mass and Energy in the Early Universe
- Matter and Antimatter
- The Forces of Nature
- Fine-Tuning in Cosmology
- The Anthropic Principle in Cosmology
- String Theory and Cosmology
- The Multiverse
- The Limits of Knowledge
- Questions
Chapter 18
Life On Earth
- Nature of Life
- Chemistry of Life
- Molecules of Life
- The Origin of Life on Earth
- Origin of Complex Molecules
- Miller-Urey Experiment
- Pre-RNA World
- RNA World
- From Molecules to Cells
- Metabolism
- Anaerobes
- Extremophiles
- Thermophiles
- Psychrophiles
- Xerophiles
- Halophiles
- Barophiles
- Acidophiles
- Alkaliphiles
- Radiation Resistant Biology
- Importance of Water for Life
- Hydrothermal Systems
- Silicon Versus Carbon
- DNA and Heredity
- Life as Digital Information
- Synthetic Biology
- Life in a Computer
- Natural Selection
- Tree Of Life
- Evolution and Intelligence
- Culture and Technology
- The Gaia Hypothesis
- Life and the Cosmic Environment
Chapter 19
Life in the Universe
- Life in the Universe
- Astrobiology
- Life Beyond Earth
- Sites for Life
- Complex Molecules in Space
- Life in the Solar System
- Lowell and Canals on Mars
- Implications of Life on Mars
- Extreme Environments in the Solar System
- Rare Earth Hypothesis
- Are We Alone?
- Unidentified Flying Objects or UFOs
- The Search for Extraterrestrial Intelligence
- The Drake Equation
- The History of SETI
- Recent SETI Projects
- Recognizing a Message
- The Best Way to Communicate
- The Fermi Question
- The Anthropic Principle
- Where Are They?
Cycles of Star Life and Death
White dwarf stars, imaged by JPL's Wide Field and Planetary Camera 2 on NASA's Hubble Space Telescope.
Most stars are less massive than the Sun, so they trap their heavy elements and take them to the grave. They become cooling embers called white dwarfs, with cores so dense that a teaspoonful brought to Earth would weigh as much as a mountain. Their carbon-rich material is a crystalline form of carbon; Pink Floyd gave a nod to white dwarfs in their 1975 song "Shine On You Crazy Diamond." High mass stars entomb heavy elements like carbon, neon, oxygen, and silicon in layers like an onion skin, with iron at the center.
Luckily, other stars do share their bounty with the rest of the universe. As in the line from an even earlier album by Joni Mitchell, "We are stardust, we are golden. We are billion-year-old carbon." After 10 billion years in a stable state, the Sun, like all other stars, will eventually exhaust its nuclear fuels. It will become unstable and shuck off a layer of gas containing helium and carbon, blowing a huge smoke bubble into space. Higher mass stars lose even more mass-they drop off heavy sweaters of gas into the interstellar medium. The most spectacular loss of mass occurs when the massive stars die. Massive stars digest their elements slowly and the steady absorption of neutrons ratchets elements slowly up the periodic table. At the end of their lives, titanic explosions hold the key to the rest of the story of the elements.
Sizes of a stellar mass black hole, neutron star, and a simulated city on a 40km x 40km block
With no more energy to be gained from nuclear reactions, the balance between gravity pulling and fusion pushing is disrupted for the last time. The floor drops out and massive stars collapse in a spherical free fall. This implosion creates a fantastic density and leaves behind a core of dense-packed neutrons (a neutron star is a gigantic atomic nucleus) if the star is fairly massive (1.5 to 3 times the Sun's mass) or a black hole if the star is extremely massive (3 or more times the Sun's mass). But during the collapse too much material rushes into a confined space, so most of it bounces back out in a spherical blast wave. This gas meets gas still falling in and the collision instantly creates temperatures of billions of degrees, enough to break through the iron "wall." Supernova!
Literally within seconds, explosive fusion creates elements heavier than iron, all the way up to lead. These elements surf the blast wave and mingle with the thin gruel of gas between stars. For a few days, as witnessed by Brahe and Kepler and civilizations throughout history, a supernova outshines an entire galaxy, it's dazzling enough to see in broad daylight.
Located in the constellation of Taurus, the Crab nebula is the remnant of a supernova formed from the explosion of a massive star a thousand years ago in 1054. Most elements on Earth are produced by supernova explosions. About thirty elements in the periodic chart have been detected in the interstellar medium. Supernova such as the Crab have produced the interstellar oxygen and neon atoms that are observed by IBEX
If you pause to reflect on your origin, it's as amazing as any tall tale told around a campfire. Our bodies — the iron in our blood, the oxygen in our lungs, the calcium in our bones, and the carbon and nitrogen that forms our genetic material are formed from the detritus of generation upon generation of stars that lived and died before Earth was born. The atoms in the jewelry that we adorn ourselves with, gold and silver and platinum, are glittering relics of long-gone supernovas.
The Sun is a relative latecomer in the story of star birth and death. When the first stars formed, a few hundred million years after the big bang, they were pristine balls of hydrogen and helium. They had no planets because there wasn't anything to make them from. Over billions of years, stars forged heavy elements in their cores and ejected them into space where they could become part of the gas clouds that would go on to form new stars. Generations of stars have handed down gas, steadily enriching it with silicon and oxygen to make rocks, and carbon, nitrogen, and oxygen to make life.
As carbon-based life forms, we borrow our carbon from the world around us as we grow in the womb; carbon that we'll return when we die. That same carbon is part of a much larger cosmic pageant of stellar life and death. Life is, indeed, a strange and wonderful journey.