An Introduction to Stellar Astrophysics E-Book

Francis LeBlanc

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

Seitenzahl: 557

Veröffentlichungsjahr: 2011

Beschreibung

An Introduction to Stellar Astrophysics aspires to provide the reader with an intermediate knowledge on stars whilst focusing mostly on the explanation of the functioning of stars by using basic physical concepts and observational results. The book is divided into seven chapters, featuring both core and optional content: * Basic concepts * Stellar Formation * Radiative Transfer in Stars * Stellar Atmospheres * Stellar Interiors * Nucleosynthesis and Stellar Evolution and * Chemically Peculiar Stars and Diffusion. Student-friendly features include: * Detailed examples to help the reader better grasp the most important concepts * A list of exercises is given at the end of each chapter and answers to a selection of these are presented. * Brief recalls of the most important physical concepts needed to properly understand stars. * A summary for each chapter * Optional and advanced sections are included which may be skipped without interfering with the flow of the core content. This book is designed to cover the most important aspects of stellar astrophysics inside a one semester (or half-year) course and as such is relevant for advanced undergraduate students following a first course on stellar astrophysics, in physics or astronomy programs. It will also serve as a basic reference for a full-year course as well as for researchers working in related fields.

Leseprobe

Contents

Preface

Acknowledgments

Chapter 1: Basic Concepts

1.1 Introduction

1.2 The Electromagnetic Spectrum

1.3 Blackbody Radiation

1.4 Luminosity, Effective Temperature, Flux and Magnitudes

1.5 Boltzmann and Saha Equations

1.6 Spectral Classification of Stars

1.7 The Hertzsprung–Russell Diagram

1.8 Summary

1.9 Exercises

Chapter 2: Stellar Formation

2.1 Introduction

2.2 Hydrostatic Equilibrium

2.3 The Virial Theorem

2.4 The Jeans Criterion

2.5 Free-Fall Times†

2.6 Pre-Main-Sequence Evolution†

2.7 Summary

2.8 Exercises

Chapter 3: Radiative Transfer in Stars

3.1 Introduction

3.2 Radiative Opacities

3.3 Specific Intensity and Radiative Moments

3.4 Radiative Transfer Equation

3.5 Local Thermodynamic Equilibrium

3.6 Solution of the Radiative-Transfer Equation

3.7 Radiative Equilibrium

3.8 Radiative Transfer at Large Optical Depths

3.9 Rosseland and Other Mean Opacities

3.10 Schwarzschild–Milne Equations††

3.11 Demonstration of the Radiative-Transfer Equation†

3.12 Radiative Acceleration of Matter and Radiative Pressure†

3.13 Summary

3.14 Exercises

Chapter 4: Stellar Atmospheres

4.1 Introduction

4.2 The Grey Atmosphere

4.3 Line Opacities and Broadening

4.4 Equivalent Width and Formation of Atomic Lines

4.5 Atmospheric Modelling

4.6 Summary

4.7 Exercises

Chapter 5: Stellar Interiors

5.1 Introduction

5.2 Equations of Stellar Structure

5.3 Energy Transport in Stars

5.4 Polytropic Models

5.5 Structure of the Sun

5.6 Equation of State

5.7 Variable Stars and Asteroseismology

5.8 Summary

5.9 Exercises

Chapter 6: Nucleosynthesis and Stellar Evolution

6.1 Introduction

6.2 Generalities Concerning Nuclear Fusion

6.3 Models of the Nucleus†

6.4 Basic Physics of Nuclear Fusion

6.5 Main-Sequence Burning

6.6 Helium-Burning Phase

6.7 Advanced Nuclear Burning

6.8 Evolutionary Tracks in the H–R Diagram

6.9 Stellar Clusters

6.10 Stellar Remnants

6.11 Novae and Supernovae†

6.12 Heavy Element Nucleosynthesis: s, r and p Processes†

6.13 Nuclear Reaction Cross Sections and Rates††

6.14 Summary

6.15 Exercises

Chapter 7: Chemically Peculiar Stars and Diffusion†

7.1 Introduction and Historical Background

7.2 Chemically Peculiar Stars

7.3 Atomic Diffusion Theory††

7.4 Radiative Accelerations††

7.5 Other Transport Mechanisms††

7.6 Summary

7.7 Exercises

Answers to Selected Exercises

Appendix A: Physical Constants

Appendix B: Units in the cgs and SI Systems

Appendix C: Astronomical Constants

Appendix D: Ionisation Energies (in eV) for the First Five Stages of Ionisation for the Most Important Elements

Appendix E: Solar Abundances for the Most Important Elements

Appendix F: Atomic Masses

Appendix G: Physical Parameters for Main-Sequence Stars

Appendix H: Periodic Table of the Elements

References

Bibliography

Index

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Library of Congress Cataloging-in-Publication Data

LeBlanc, Francis.An introduction to stellar astrophysics/Francis LeBlanc.p. cm.Includes bibliographical references and index.ISBN 978-0-470-69957-7 (cloth) – ISBN 978-0-470-69956-0 (pbk.) 1. Stars–Textbooks.2. Astrophysics--Textbooks. I. Title.QB801.L43 2010523.8–dc222009052138

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

ISBN: H/bk 978-0470-699577 P/bk 978-0470-699560

Cover photo:Image courtesy of NASA images.org

To Marise

Preface

This textbook is designed to be used by students following a first course on stellar astrophysics. It is mostly aimed at the advanced undergraduate students in physics or astronomy programs. It may also serve as a basic reference for researchers working in fields other than stellar astrophysics.

This work is not encyclopaedic in nature and therefore does not cover, for example, all type of stars that exist in the universe. This book aspires to give intermediate knowledge on stars in a relatively concise format. It focuses mostly on the explanation of the functioning of stars by using basic physical concepts and observational results. A large number of graphs and figures are included to better explain the concepts covered. Only essential astronomical data are given. The amount of observational results shown is deliberately limited in scope since a too large quantity of observational data can be overwhelming and be counterproductive to newcomers to the field of stellar astrophysics.

This book is written in the scope of the students’ needs. Although the students using this book should have seen all the physical concepts needed for exploring stellar astrophysics, brief recalls of the most important ones are given. No prior astronomical knowledge is assumed. This work can therefore be used not only by astronomy students but also by students in a physics program. This book aims to explain stellar astrophysics with clarity and is written in a manner so that it could be read and understood by a physics or astronomy student with little or no outside help. Detailed examples are given throughout the book to help the reader better grasp the most important concepts. A list of exercises is given at the end of each chapter and answers to a selection of these are given. A summary for each chapter is also presented.

Some historical snippets are added to give some perspective on the chronology of various discoveries along with giving merited acknowledgments to the researchers that made these advancements possible. For a complete historical review of stellar astrophysics, the reader is referred to Tassoul, J.-L. and Tassoul, M., A Concise History of Solar and Stellar Physics, Princeton University Press, Princeton (2004).

The book is divided in seven chapters: basic concepts, stellar formation, radiative transfer in stars, stellar atmospheres, stellar interiors, nucleosynthesis and stellar evolution and chemically peculiar stars and diffusion. The topics seen in the last chapter are rarely covered in such textbooks and distinguish it from others on stellar astrophysics. This chapter encompasses many concepts seen throughout the book.

The book is divided in core content (approximately 75%) which is considered crucial for a global understanding of stars and in optional content (about 25%). Some optional sections also contain more advanced topics. Sections marked† are optional, while those marked†† are optional sections containing advanced topics. These sections may be skipped without interfering in the normal progression of the core topics.

This book is mainly designed to cover the most important aspects of stellar astrophysics inside a one - semester (or half - year) course. The book is, however, somewhat too lengthy to be covered in totality in a single semester. The professor may then choose to skip a certain number of the optional or advanced sections in according to the length of the course given.

Some universities have two one - semester introductory courses (or a full - year course) in stellar astrophysics. They are usually divided into a course on stellar atmospheres, and a second one, pertaining to stellar structure and evolution. This book could be used as the main reference book for two such courses. Chapters 1, 3, 4 along with the first three sections of Chapter 2 could be given as a stellar atmosphere course, while the remainder of Chapter 2 and Chapters 5 and 6 could be given as a stellar interior and evolution course. Chapter 7 could also be seen at the end of either of these courses.

This book could also be used as the main reference for a first course on stellar astrophysics at the graduate level where the professor could choose to give additional selected readings to students to deepen their understanding of certain topics.

Francis LeBlancMoncton, CanadaOctober 2009

Acknowledgments

Since the writing of this book encapsulates many years of study and research on the subject, it is natural that I extend my warmest thanks to the many professors I encountered during my studies, especially, Georges Bader, Guilio Bosi, Claude Carignan, Donald Duplain, Gilles Fontaine, Georges Michaud, Jean - Louis Tassoul, Hubert Reeves, Thomas Richard, François Söler and Fran ç ois Wesemaël, who have guided me and often stoked my interest in physics and astronomy.

In view of the fact that this book is an offshoot of lecture notes that I have prepared for physics and astrophysics courses at Université de Moncton, I thank the many students who have contributed to improving some of the material presented. I wish to underline the contribution of Issouf Kafando, Luc LeBlanc, Marc Richard and Mouhamadou Thiam.

I also thank my colleagues and the staff at our department who were very supportive in this endeavour, especially Francine Maillet. I also thank the many colleagues from all over the world with whom I have collaborated in my research and who graciously shared their passion and wisdom. I am also grateful to the National Sciences and Engineering Research Council of Canada and La Faculté des Études Supérieures et de la Recherche del’ Université de Moncton for funding my research projects.

I also want to express my gratitude to the following people: Georges Alecian, Gibor Basri, Normand Beaudoin, Martin Bolduc, David Branch, Robert Duncan, Robert Hawkes, Gregory Laughlin, Jaymie Matthews, Art McDonald, John R. Percy, Jacques Richer, Ruben Sandapen, John Sichel, Christopher Thompson, Mathieu Vick and Francis Weil, who have given helpful comments on various parts of this book. I especially thank Viktor Khalack who has graciously read most of this book. His many comments led to major improvements in the manuscript. Of course, these individuals are in no way responsible for any errors or omissions that might appear in this book.

I also wish to thank Alexandra Carrick, Richard Davies, Judith Irwin and Sophia Travis for helping me navigate through the publication process.

I also express my gratitude to my family who has supported me in many ways throughout the years. Finally, my warmest thanks go to my dear wife Marise, who has shown great patience and has graciously accepted my relative absence during the writing of this book.