Introduction to Astronomy and Cosmology E-Book

Ian Morison

• Herausgeber: John Wiley & Sons
• Kategorie: Lebensstil
• Sprache: Englisch

Seitenzahl: 559

Veröffentlichungsjahr: 2013

Beschreibung

Introduction to Astronomy & Cosmology is a modern undergraduate textbook, combining both the theory behind astronomy with the very latest developments. Written for science students, this book takes a carefully developed scientific approach to this dynamic subject. Every major concept is accompanied by a worked example with end of chapter problems to improve understanding * Includes coverage of the very latest developments such as double pulsars and the dark galaxy. * Beautifully illustrated in full colour throughout * Supplementary web site with many additional full colour images, content, and latest developments.

Leseprobe

Contents

Preface

Author’s Biography

Chapter 1: Astronomy, an Observational Science

1.1 Introduction

1.2 Galileo Galilei’s proof of the Copernican theory of the solar system

1.3 The celestial sphere and stellar magnitudes

1.4 The celestial coordinate system

1.5 Precession

1.6 Time

1.7 A second major observational triumph: the laws of planetary motion

1.8 Measuring the astronomical unit

1.9 Isaac Newton and his Universal Law of Gravity

1.10 Experimental measurements of G, the Universal constant of gravitation

1.11 Gravity today: Einstein’s special and general theories of relativity

1.12 Conclusion

1.13 Questions

Chapter 2: Our Solar System 1 – The Sun

2.1 The formation of the solar system

2.2 The Sun

2.3 Nuclear fusion

2.4 The solar neutrino problem 5

2.5 The solar atmosphere: photosphere, chromosphere and corona

2.6 The solar wind

2.7 The sun’s magnetic field and the sunspot cycle

2.8 Prominences, flares and the interaction of the solar wind with the earth’s atmosphere

2.9 Solar eclipses

2.10 Questions

Chapter 3: Our Solar System 2 – The Planets

3.1 What is a planet?

3.2 Planetary orbits

3.3 Planetary properties

3.4 Planetary atmospheres

3.5 The planets of the solar system

3.6 Comets

3.7 Questions

Chapter 4: Extra-solar Planets

4.1 The radial velocity (Doppler wobble) method of planetary detection

4.2 Planetary transits

4.3 Gravitational microlensing

4.4 Astrometry

4.5 Discovery space

4.6 Selection effects and the likelihood of finding solar systems like ours

4.7 Questions

Chapter 5: Observing the Universe

5.1 Thinking about optics in terms of waves rather than rays

5.2 The human eye

5.3 The use of a telescope or pair of binoculars to see fainter objects

5.4 Using a telescope to see more detail in an image

5.5 The magnification of a telescope

5.6 Image contrast

5.7 The classic Newtonian telescope

5.8 The Cassegrain telescope

5.9 Catadioptric telescopes

5.10 Active and adaptive optics

5.11 Some significant optical telescopes

5.12 Radio telescopes

5.13 Observing in other wavebands

5.14 Observing the universe without using electromagnetic radiation

5.15 Questions

Chapter 6: The Properties of Stars

6.1 Stellar luminosity

6.2 Stellar distances

6.3 Proper motion

6.4 The absolute magnitude scale

6.5 Colour and surface temperature

6.6 Stellar photometry

6.7 Stellar spectra

6.8 Spectroscopic parallax

6.9 The Hertzsprung–Russell Diagram

6.10 The size of stars

6.11 The masses and densities of stars

6.12 The stellar mass–luminosity relationship

6.13 Stellar lifetimes

6.14 Questions

Chapter 7: Stellar Evolution – The Life and Death of Stars

7.1 Low mass stars: 0.05–0.5 solar masses

7.2 Mid mass stars: 0.5–∼8 solar masses

7.3 Variable stars

7.4 Planetary nebula

7.5 White dwarfs

7.6 The evolution of a sun–like star

7.7 Evolution in close binary systems – the Algol paradox

7.8 High mass stars in the range > 8 solar masses

7.9 Type II supernova

7.10 Neutron stars and black holes

7.11 The discovery of pulsars

7.12 Pulsars as tests for general relativity

7.13 Black holes

7.14 Questions

Chapter 8: Galaxies and the Large Scale Structure of the Universe

8.1 The Milky Way

8.2 Other galaxies

8.3 The universe

8.4 Questions

Chapter 9: Cosmology – the Origin and Evolution of the Universe

9.1 Einstein’s blunder?

9.2 Big Bang models of the universe

9.3 The blueshifts and redshifts observed in the spectra of galaxies

9.4 The expansion of the universe

9.5 The steady state model of the universe

9.6 Big Bang or Steady State?

9.7 The cosmic microwave background

9.8 Inflation

9.9 The Big Bang and the formation of the primeval elements

9.10 The ‘ripples’ in the Cosmic Microwave Background

9.11 How dark matter affects the cosmic microwave background

9.12 The hidden universe: dark matter and dark energy

9.13 The makeup of the universe

9.14 A universe fit for intelligent life

9.15 Intelligent life in the universe

9.16 The future of the universe

Index

This edition first published 2008

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Library of Congress Cataloging-in-Publication Data

Morison, Ian, 1943–

Introduction to astronomy and cosmology / Ian Morison.

p. cm.

Includes bibliographical references and index.

ISBN 978-0-470-03333-3 (cloth) — ISBN 978-0-470-03334-0 (pbk.: alk.paper)

1. Astronomy—Textbooks. 2. Cosmology—Textbooks. I. Title.

QB43.3.M67 2008

520—dc22

2008029112

A catalogue record for this book is available from the British Library.

To the memory of my father, Archibald, who inspired my love of astronomy, to Bernard Lovell who made it possible for me to pursue that love and to my wife, Judy, with love.

Preface

This textbook arose out of the lecture course that the author developed for first year physics and astronomy undergraduates at the University of Manchester. When it was proposed that all the students should undertake the course, not just those who had come to study astrophysics, several of the physics staff felt that it would not be appropriate for the physics students. But this view was countered with the fact that astronomy is a wonderful showcase for physics and this text covers aspects of physics ranging through Newton’s and Einstein’s theories of gravity, particle and nuclear physics and even quantum mechanics.

Not all of the material covered by the course was examinable; in particular the descriptions of the planets in our solar system and the background to some of the key discoveries of the last century. However, the author believes that this helps to give life to the subject and so these parts of the course have not been left out. Wherever possible, calculations have been included to illustrate all aspects of the book’s material, but the level of mathematics required is not high and should be well within the capabilities of first year undergraduates. The questions with each chapter have come from course examination papers and tutorial exercises and should thus be representative of the type of questions that might be asked of students studying an astronomy course based on this book.

Some textbooks are rightly described as “worthy but dull”. It is the author’s earnest hope that this book would not fit this description and that, as well a conveying the basics of astronomy in an accessible way, it will be enjoyable to read. If, perhaps, the book could inspire some who have used it to continue their study of astronomy so that, in time, they might themselves contribute to our understanding of the universe, then it would have achieved all that its author could possibly hope for.

Acknowledgements

The author would like to thank those who have helped this book to become a reality: the students who tested the questions and commented on the course material, my colleagues Phillipa Browning, Neil Jackson, Michael Peel and Peter Millington who carefully read through drafts of the text and the team at Wiley; Zoe Mills, Gemma Valler, Wendy Harvey, Andy Slade and Richard Davies who have provided help and encouragement during its writing and production.

No matter how hard we have all tried, the text may well contain some mistakes – for which the author takes full responsibility! To help eradicate them, should there be future editions, he would be most grateful if you could send comments and corrections via the website: http://www.jb.man.ac.uk/public/im/astronomy.html

This will provide additional supporting material for the book and a (hopefully small) list of corrections.

Author’s Biography

Ian Morison began his love of astronomy when, at the age of 12, he made a telescope out of lenses given to him by his optician. He went on to study Physics, Mathematics and Astronomy at Oxford and in 1970 was appointed to the staff of the University of Manchester where he now teaches astronomy, computing and electronics.

He is a past president of the Society for Popular Astronomy, one of the UK’s largest astronomical societies. He remains on the society’s council and holds the post of instrument advisor helping members with their choice and use of Telescopes.

He lectures widely on astronomy, has co-authored books for amateur astronomers and writes regularly for the two UK astronomy magazines. He also writes a monthly sky guide for the Jodrell Bank Observatory’s web site and produces an audio version as part of the Jodrell Bank Podcast. He has contributed to many television programmes and is a regular astronomy commentator on local and national radio. Another activity he greatly enjoys is to take amateur astronomers on observing trips such as those to Lapland to see the Aurora Borealis and on expeditions to Turkey and China to observe total eclipses of the Sun.

In 2003 the Minor Planets Committee of the International Astronomical Union named asteroid 15,727 in his honour, citing his work with MERLIN, the world’s largest linked array of radio telescopes, and that in searching for intelligent life beyond our Solar System in Project Phoenix. In 2007 he was appointed to the post of Gresham Professor of Astronomy. Dating from 1597, this is the oldest astronomy professorship in the world and was once held by Christopher Wren.

Chapter 1

Astronomy, an Observational Science

1.1 Introduction

Astronomy is probably the oldest of all the sciences. It differs from virtually all other science disciplines in that it is not possible to carry out experimental tests in the laboratory. Instead, the astronomer can only observe what he sees in the Universe and see if his observations fit the theories that have been put forward. Astronomers do, however, have one great advantage: in the Universe, there exist extreme states of matter which would be impossible to create here on Earth. This allows astronomers to make tests of key theories, such as Albert Einstein’s General Theory of Relativity. In this first chapter, we will see how two precise sets of observations, made with very simple instruments in the sixteenth century, were able to lead to a significant understanding of our Solar System. In turn, these helped in the formulation of Newton’s Theory of Gravity and subsequently Einstein’s General Theory of Relativity – a theory of gravity which underpins the whole of modern cosmology. In order that these observations may be understood, some of the basics of observational astronomy are also discussed.

1.2 Galileo Galilei’s proof of the Copernican theory of the solar system

One of the first triumphs of observational astronomy was Galileo’s series of observations of Venus which showed that the Sun, not the Earth, was at the centre of the Solar System so proving that the Copernican, rather than the Ptolemaic, model was correct (Figure 1.1).

In the Ptolemaic model of the Solar System (which is more subtle than is often acknowledged), the planets move around circular ‘epicycles’ whose centres move around the Earth in larger circles, called deferents, as shown in Figure 1.2. This enables it to account for the ‘retrograde’ motion of planets like Mars and Jupiter when they appear to move backwards in the sky. It also models the motion of Mercury and Venus. In their case, the deferents, and hence the centre of their epicycles, move around the Earth at the same rate as the Sun. The two planets thus move around in circular orbits, whose centres lie on the line joining the Earth and the Sun, being seen either before dawn or after sunset. Note that, as Mercury stays closer to the Sun than Venus, its deferent and epicycle are closer than that of Venus – in the Ptolemaic model, Mercury is the closest planet to the Earth!

Figure 1.1 Galileo Galilei: a portrait by Guisto Sustermans. Image: Wikipeda Commons.

Figure 1.2 The centre points of the epicycles for Mercury and Venus move round the Earth with the same angular speed as the Sun.

In the Ptolemaic model, Venus lies between the Earth and the Sun and hence it must always be lit from behind, so could only show crescent phases whilst its angular size would not alter greatly. In contrast, in the Copernican model Venus orbits the Sun. When on the nearside of the Sun, it would show crescent phases whilst, when on its far side but still visible, it would show almost full phases. As its distance from us would change significantly, its angular size (the angle subtended by the planet as seen from the Earth) would likewise show a large change.

Figure 1.3 shows a set of drawings of Venus made by Galileo with his simple refracting telescope. They are shown in parallel with a set of modern photographs which illustrate not only that Galileo showed the phases, but that he also drew the changing angular size correctly. These drawings showed precisely what the Copernican model predicts: almost full phases when Venus is on the far side of the Sun and a small angular size coupled with thin crescent phases, having a significantly larger angular size, when it is closest to the Earth.