Introduction to Stellar Structure

223 Pages·2016·2.931 MB·English

by  Walter J. Maciel (auth.)

Introduction
to Stellar Structure
Walter J. Maciel
Springer Praxis Books:
Astronomy and Planetary Sciences
Serieseditors
E.IanRobson
DerekWard-Thompson
Moreinformationaboutthisseriesathttp://www.springer.com/series/4175

Walter J. Maciel
Introduction to
Stellar Structure
123
WalterJ.Maciel
DepartamentodeAstronomia
CidadeUniversitariaIAG/USP
SãoPaulo,Brazil
SpringerPraxisBooks:AstronomyandPlanetarySciences
OriginalPortuguesetitle:IntroduçãoàEstruturaeEvoluçãoEstelar(c)1999byEditorada
UniversidadedeSãoPaulo
SpringerPraxisBooks
ISBN978-3-319-16141-9 ISBN978-3-319-16142-6 (eBook)
DOI10.1007/978-3-319-16142-6
SpringerChamHeidelbergNewYorkDordrechtLondon
LibraryofCongressControlNumber:2015947839
©SpringerInternationalPublishingSwitzerland2016
Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpartof
thematerialisconcerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation,
broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmissionorinformation
storageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilarmethodology
nowknownorhereafterdeveloped.Exemptedfromthislegalreservationarebriefexcerptsinconnection
with reviews or scholarly analysis or material supplied specifically for the purpose of being entered
and executed on a computer system, for exclusive use by the purchaser of the work. Duplication of
this publication or parts thereof is permitted only under the provisions of the Copyright Law of the
Publisher’slocation,initscurrentversion,andpermissionforusemustalwaysbeobtainedfromSpringer.
PermissionsforusemaybeobtainedthroughRightsLinkattheCopyrightClearanceCenter.Violations
areliabletoprosecutionundertherespectiveCopyrightLaw.
Theuseofgeneraldescriptivenames,registerednames,trademarks,servicemarks,etc.inthispublication
doesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfromtherelevant
protectivelawsandregulationsandthereforefreeforgeneraluse.
While the advice and information in this book are believed to be true and accurate at the date of
publication,neithertheauthorsnortheeditorsnorthepublishercanacceptanylegalresponsibilityfor
anyerrorsoromissionsthatmaybemade.Thepublishermakesnowarranty,expressorimplied,with
respecttothematerialcontainedherein.
Cover illustration: The open cluster NGC 290: A Stellar Jewel Box. Image Credit: ESA & NASA;
Acknowledgement:E.Olszewski(U.Arizona)
Printedonacid-freepaper
SpringerInternationalPublishingAGSwitzerlandispartofSpringerScience+BusinessMedia(www.
springer.com)
Whenyouunderstandthelawsofphysics,
Penny,anythingispossible.
SheldonCooper
ForDenise,Mariana,Cristina,and
Francisco

Preface
This book is based on the lecture notes of a graduate course on stellar structure
and evolution delivered at the Astronomy Department, University of São Paulo.
The stellar structure concepts are discussed in detail, since the physical processes
involved are usually well known, but this book is not a complete course on stellar
structure,andjustanintroductiontothemaincharacteristicsofthisfield.Thebook
canbeusefulinadvancedundergraduatecoursesorinbeginninggraduatecourses
forphysicsstudents,andalsotoreadersinterestedinstellarastrophysicshavingan
adequatemathematicalbackground.
Each chapter includes a few exercises, aiming at fixing the main concepts
introduced in the text, and, particularly, intending to make the reader familiar
with the numerical values of the main astrophysical quantities involved in stellar
structure.Solutionsofallexercisesareoutlinedattheendofthebook.
All the book chapters make an effort to derive simple estimates of the relevant
quantities in the physics of the stellar interiors. These estimates are sometimes
crude, but are based on elementary physical principles. Current stellar models
always demand the use of numerical methods, in which these principles are not
alwaysveryclear,whichincreasestheneedofobtainingestimatesbasedonsimple
concepts,althoughwithapproximateresults.
Several people contributed to the completion of this book, especially some
colleaguesattheAstronomyDepartmentandgraduatestudents,whohavepointed
out some mistakes and incorrections in preliminary versions of this text. I am
indebted to them all, especially to my colleagues Eduardo Janot Pacheco and
RobertoBoczkoforthemanycorrectionsandsuggestions.Naturally,allerrorsand
omissionsstillpresentinthetextaremyownresponsibility.
The present edition is a translation of the book originally published in 1999.
A few mistakes have been corrected, the bibliography was updated, and several
new examples andapplications have been included, aswellasthesolutionsofthe
problems,butthemaingoalsoftheoriginaleditionhavebeenpreserved.
SãoPaulo,Brazil WalterJ.Maciel
vii

Contents
1 PhysicalPropertiesoftheStars .......................................... 1
1.1 Introduction........................................................... 1
1.2 MagnitudeandColourIndex ........................................ 1
1.3 LuminosityandBolometricCorrection ............................. 4
1.4 EffectiveTemperature................................................ 5
1.5 SpectralTypeandLuminosityClass ................................ 5
1.6 MassandRadius ..................................................... 7
1.7 GravityandAverageDensity........................................ 11
1.8 Rotation............................................................... 13
1.9 ChemicalComposition............................................... 14
1.10 StellarPopulations ................................................... 14
2 PhysicalConditionsintheStellarInterior .............................. 19
2.1 Introduction........................................................... 19
2.2 TheMassContinuityEquation ...................................... 19
2.3 TheHydrostaticEquilibriumEquation.............................. 21
2.3.1 DeviationsfromHydrostaticEquilibrium................ 22
2.3.2 TheFree-FallTimescale .................................. 24
2.3.3 TheMassLossRateinStars.............................. 24
2.3.4 DeviationsfromSphericalSymmetry.................... 25
2.4 AverageDensity...................................................... 26
2.5 PressureandTemperature............................................ 26
2.6 ExistenceofThermodynamicEquilibrium.......................... 28
2.7 StellarEnergy ........................................................ 29
2.7.1 ThermalEnergy ........................................... 29
2.7.2 GravitationalEnergy...................................... 30
2.7.3 NuclearEnergy:TheProton–ProtonReaction........... 32
2.7.4 TheJeansMass............................................ 33
2.8 TheEnergyProductionRate......................................... 34
ix