Contents
General Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VII
Part I A Century of Revolution in Our Vision of the Universe . . . . . . . . . . 1
CHAPTER 1
General View of 20th Century Astronomy and Its Starting Point . . . . . . . . . 3
1.1 Astronomy, the Key to Our Vision of the World . . . . . . . . . . . . . . . . . 3
1.2 Benchmarks on 1900 Astronomy and Its Shortcomings . . . . . . . . . . . . 7
CHAPTER 2
Scientific and Technical Revolutions, Drivers of 20th Century Astronomy . . . 21
2.1 Physics Revolutions, Keys to Astrophysics . . . . . . . . . . . . . . . . . . . . . 21
2.2 Giant Telescopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.3 Overcoming the Disturbances of the Earth Atmosphere. . . . . . . . . . . . 24
2.4 Exploiting All Spectral Domains from Radio to X-ray and Gamma-ray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.5 Visiting the Planets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.6 No Pause in the Progress of Signal Detection and Exploitation . . . . . . 35
Part II Stars are Well Understood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
CHAPTER 3
How does a Star Work? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.1 Understanding the Stars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.2 Solving the Mystery of the Origin of the Energy of the Sun and the Stars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.3 The Life of the Stars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.4 Our Atoms were Born in the Stars . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.5 Stars also Die . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
CHAPTER 4
Complexities of Star Birth and Physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.1 General Star Formation Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.2 Young Infrared Stars: Born in Dusty Cocoons . . . . . . . . . . . . . . . . . . . 59
4.3 Gravitational Contraction, Accretion and Discs. . . . . . . . . . . . . . . . . . 59
4.4 Universality of Stellar Pairs – Complex Ending of Their Lives . . . . . . . 61
4.5 Brown Dwarfs, Billions of Aborted Stars . . . . . . . . . . . . . . . . . . . . . . . 63
4.6 Stars are Still at the Forefront of Current Astronomy . . . . . . . . . . . . . 65
4.7 Stars and Ecology of Planets and Galaxies . . . . . . . . . . . . . . . . . . . . . 68
Part III The New World of Galaxies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
CHAPTER 5
Discovery of Galaxies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.1 The Appreciation of the Nature of Galaxies Dates Back Only to the Beginning of the 20th Century . . . . . . . . . . . . . 73
5.2 First Steps in the World of Nearby Galaxies . . . . . . . . . . . . . . . . . . . . 77
5.3 Architecture and Stellar Content of Galaxies . . . . . . . . . . . . . . . . . . . . 81
CHAPTER 6
Our Galaxy and Its Interstellar Medium . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
6.1 Exploration of Our Galaxy, the Milky Way . . . . . . . . . . . . . . . . . . . . . 83
6.2 An Ordinary Galaxy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
6.3 Current Organization of Stars Resulting from the Milky Way History . 86
6.4 The Interstellar Gas, a Key Player in the Evolution of Galaxies . . . . . 86
6.5 Other Players in the Interstellar Medium . . . . . . . . . . . . . . . . . . . . . . 90
6.6 Exotic Components of the Milky Way . . . . . . . . . . . . . . . . . . . . . . . . . 94
CHAPTER 7
Hundreds of Billions of Galaxies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
7.1 Galaxies at All Stages of Their Life . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
7.2 The Turbulent Family Life of Galaxies . . . . . . . . . . . . . . . . . . . . . . . . 99
7.3 Understanding the Formation and Evolution of Galaxies . . . . . . . . . . . 106
Part IV Cosmology, the Science of the Universe as a Whole . . . . . . . . . . . . 109
CHAPTER 8
Birth of Cosmology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
8.1 The Universe of Galaxies is Expanding . . . . . . . . . . . . . . . . . . . . . . . . 111
8.2 The Saga of the Big Bang Confirmation . . . . . . . . . . . . . . . . . . . . . . . 114
8.3 The Very First Phase in the History of the Universe: Uncertain Physics . . . . . . . . . . . . . . . . . . . 116
8.4 AWell-Understood Second Phase: The Standard Big Bang Model . . . . 118
CHAPTER 9
Content of the Universe and Structure Formation . . . . . . . . . . . . . . . . . . . . . 123
9.1 Formation of Galaxies and Structures of the Present Universe . . . . . . . 123
9.2 Fundamental Parameters of the Universe are Better Known than Its Physics . . . . . . . . . . . . . . . . . . 125
9.3 Age of the Universe and Variations of the Determinations of the Hubble Constant . . . . . . . . . . . . . . 128
9.4 An Overall Density Very Close to the Critical Density . . . . . . . . . . . . 128
9.5 Need and Nature of Dark Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
9.6 A Last-Minute Surprise, the Re-Acceleration of the Expansion Involving an Unknown Source of Cosmic Energy . . . . . . . 131
9.7 Summarizing: An Unexpected Universe Model Validated in Multiple Ways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Part V Singular Stars and Cataclysms in Extreme Physical Conditions . . . 135
CHAPTER 10
Explosions of Stars and Their Singular Residues . . . . . . . . . . . . . . . . . . . . . . 137
10.1 Extreme Physics of Supernova Implosion/Explosion . . . . . . . . . . . . . 137
10.2 Neutron Stars, Hyper-Dense Supernova Residues. . . . . . . . . . . . . . . . 145
10.3 Gamma-Ray Bursts, Even More Powerful Bursts . . . . . . . . . . . . . . . . 147
10.4 Cosmic Rays, Messenger Particles of the High Energy Universe . . . . . 149
CHAPTER 11
Black Holes and Their Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
11.1 Black Holes, General Relativity and the Cosmos . . . . . . . . . . . . . . . . 155
11.2 Stellar Black Holes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
11.3 GravitationalWaves, Propagation of Spacetime-Curvature Disturbances. . . 158
11.4 Quasars: New Stars a Thousand Times Brighter than Galaxies . . . . . 162
11.5 Manifestations of Super-Massive Black Holes and Their Interpretation . . . 164
11.6 Co-evolution of Galaxies and Their Black Hole . . . . . . . . . . . . . . . . . 170
11.7 The Super-Massive Black Hole of Our Galaxy and Others . . . . . . . . . 171
Part VI Planets, in the Solar System and Outside . . . . . . . . . . . . . . . . . . . 173
CHAPTER 12
Direct Exploration of the Planets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
12.1 Planets, Stars of Astronomy until the 19th Century . . . . . . . . . . . . . 175
12.2 Half a Century Without Revolution for Planetology . . . . . . . . . . . . . 178
12.3 Humans Went to the Moon! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
12.4 We Broadly Understand the Origin of the Moon and Its Importance for the Earth . . . . . . . . . . . . . . . . . . . . . 181
12.5 Very Rich Close-up Photos of All the Bodies of the Solar System . . . 183
12.6 Summary of Planetary Expeditions . . . . . . . . . . . . . . . . . . . . . . . . . . 184
12.7 Searching for Life in the Solar System: Where and When? . . . . . . . . . 191
CHAPTER 13
Entering the Dream World of Exoplanets . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
13.1 Explosion of Discoveries of New Planets . . . . . . . . . . . . . . . . . . . . . . 197
13.2 The Majority of Stars have a Planetary System. . . . . . . . . . . . . . . . . 201
13.3 Surprising Variety of Exoplanets . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
13.4 The Search for Earth-Like Planets. . . . . . . . . . . . . . . . . . . . . . . . . . . 204
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
CHAPTER 14
A New Cosmos in the 21st Century?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
14.1 A New Cosmos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
14.2 Auguries for 21st Century Astronomy? . . . . . . . . . . . . . . . . . . . . . . . 212
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Acronyms and Space Missions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
The asterisks * indicate words or acronyms whose meaning is explained in the
“Glossary” or “Acronyms and space missions” sections at the end of the book.
