Atomic Astrophysics and Spectroscopy Anil K. Pradhan

377 Pages·2012·6.49 MB·English

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AtomicAstrophysicsandSpectroscopy
Spectroscopyallowstheprecisestudyofastronomicalobjectsand
phenomena.Bridgingthegapbetweenphysicsandastronomy,thisisthe
firstintegratedgraduate-leveltextbookonatomicastrophysics.Itcovers
thebasicsofatomicphysicsandastrophysics,includingstate-of-the-art
researchapplications,methodsandtools.
Thecontentisevenlybalancedbetweenthephysicalfoundationsof
spectroscopyandtheirapplicationstoastronomicalobjectsand
cosmology.Anundergraduateknowledgeofphysicsisassumed,and
relevantbasicmaterialissummarisedatthebeginningofeachchapter.
Thematerialiscompletelyself-containedandcontainssufficient
backgroundinformationforself-study.Advanceduserswillfindituseful
forspectroscopicstudies.Websiteshostedbytheauthorscontainupdates,
corrections,exercisesandsolutions,andnewsitemsfromphysicsand
astronomyrelatedtospectroscopy.Linkstothesecanbefoundat
www.cambridge.org/9780521825368.
ANILK.PRADHANisaProfessorintheDepartmentofAstronomy,the
ChemicalPhysicsProgram,andtheBiophysicsGraduateProgramatThe
OhioStateUniversity.Hehastaughtacourseonastrophysical
spectroscopyforthepast20yearsatTheOhioStateUniversity.
SULTANAN.NAHARisaSeniorResearchScientistintheDepartmentof
AstronomyatTheOhioStateUniversity.Shehasanextensivebackground
inatomicphysicsandastrophysicsandisoneoftheforemostresearchers
onatomicprocesses.

Atomic
Astrophysics
and
Spectroscopy
Anil K. Pradhan
and
Sultana N. Nahar
Department of Astronomy
The Ohio State University
CAMBRIDGE UNIVERSITY PRESS
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SãoPaulo,Delhi,Dubai,Tokyo,MexicoCity
CambridgeUniversityPress
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PublishedintheUnitedStatesofAmericabyCambridgeUniversityPress,NewYork
www.cambridge.org
Informationonthistitle:www.cambridge.org/9780521825368
©A.K.PradhanandS.N.Nahar2011
Thispublicationisincopyright.Subjecttostatutoryexception,
andtotheprovisionsofrelevantcollectivelicensingagreements,
noreproductionofanypartmaytakeplacewithoutthewritten
permissionofCambridgeUniversityPress.
Firstpublished2011
PrintedintheUnitedKingdomattheUniversityPress,Cambridge
AcataloguerecordforthispublicationisavailablefromtheBritishLibrary
LibraryofCongressCataloguinginPublicationdata
Pradhan,AnilK.
Atomicastrophysicsandspectroscopy/AnilK.PradhanandSultanaN.Nahar.
p. cm.
Includesbibliographicalreferencesandindex.
ISBN978-0-521-82536-8
1. Atomicspectroscopy. 2. Astronomicalspectroscopy. I. Nahar,SultanaN.
II. Title.
QC454.A8P73 2011
(cid:2)
523.0197–dc22
2010036196
ISBN978-0-521-82536-8Hardback
CambridgeUniversityPresshasnoresponsibilityforthepersistenceor
accuracyofURLsforexternalorthird-partywebsitesreferredto
inthispublication,anddoesnotguaranteethatanycontentonsuch
websitesis,orwillremain,accurateorappropriate.
Contents
Preface pageix
Acknowledgements xi
1 Introduction 1
1.1 Atomicastrophysicsandspectroscopy 1
1.2 Chemicalandphysicalpropertiesofelements 2
1.3 Electromagneticspectrumandobservatories 4
1.4 Astrophysicalandlaboratoryplasmas 5
1.5 Particledistributions 6
1.6 Quantumstatistics 10
1.7 Spectroscopyandphotometry 11
1.8 Spectroscopicnotation 12
1.9 Unitsanddimensions 13
2 Atomicstructure 15
2.1 Thehydrogenatom 16
2.2 Quantumnumbersandparity 19
2.3 SpectrallinesandtheRydbergformula 20
2.4 Spectroscopicdesignation 21
2.5 Thegroundstateofmulti-electronsystems 23
2.6 Empiricalrulesforelectronicconfigurations 25
2.7 Intermediatecouplingandjjcoupling 25
2.8 Hund’srules 26
2.9 Rydbergformulawithquantumdefect 27
2.10 Multi-electronatomicsystems 29
2.11 TheHartree–Fockmethod 30
2.12 Central-fieldapproximation 35
2.13 Relativisticfinestructure 37
3 Atomicprocesses 46
3.1 Bound,continuumandresonancestates 47
3.2 Collisionalandradiativeatomicprocesses 49
3.3 Theoreticalapproximations 53
3.4 Theclosecouplingapproximation 56
3.5 TheR-matrixmethod 59
3.6 Approximatemethods 65
vi Contents
4 Radiativetransitions 72
4.1 EinsteinAandBcoefficients 73
4.2 Electronmotioninanelectromagneticfield 75
4.3 Transitionmatrixelements 77
4.4 Multipoleexpansion 78
4.5 Electricdipoleapproximation 78
4.6 Central-fieldapproximation 81
4.7 Length,velocityandacceleration 84
4.8 Oscillatorstrengthsforhydrogen 85
4.9 Configurationinteraction 86
4.10 Finestructure 87
4.11 R-matrixtransitionprobabilities 88
4.12 Higher-ordermultipoletransitions 91
4.13 SelectionrulesandZ-scaling 93
4.14 Dipoleandnon-dipoletransitionsinHe-likeions 93
4.15 Angularalgebraforradiativetransitions 94
5 Electron–ioncollisions 97
5.1 Electronimpactexcitation(EIE) 98
5.2 Theoreticalapproximations 101
5.3 Excitationratecoefficients 104
5.4 Atomiceffects 105
5.5 Scalingofcollisionstrengths 111
5.6 Comparisonwithexperiments 112
5.7 Electronimpactexcitationdata 115
5.8 Electronimpactionization 115
5.9 Augereffect 117
6 Photoionization 120
6.1 Hydrogenandhelium 121
6.2 Photoionizationcrosssection 122
6.3 Bound–freetransitionmatrixelement 122
6.4 Centralpotential 124
6.5 Generalizedbound–freetransitionprobability 126
6.6 Channelcouplingandresonances 128
6.7 Experimentalmeasurements 137
6.8 Resonance-averagedcrosssection 137
6.9 Radiationdampingofresonances 139
6.10 Angulardistributionandasymmetry 144
7 Electron–ionrecombination 147
7.1 Detailedbalance 148
7.2 Totalelectron–ionrecombinationrate 148
7.3 IndependenttreatmentsforRRandDR 149
7.4 Theunifiedtreatment 153
7.5 Photorecombinationanddielectronicrecombination 163
7.6 Dielectronicsatellitelines 164
7.7 RecombinationtoHandH-likeions 169
7.8 Ionizationequilibrium 169
7.9 Effectiverecombinationratecoefficient 173
7.10 Plasmaeffects 174
Contents vii
8 Multi-wavelengthemissionspectra 175
8.1 Emissionlineanalysis 176
8.2 Collisional-radiativemodel 178
8.3 Spectraldiagnostics:visiblelines 179
8.4 X-raylines:theheliumisoelectronicsequence 183
8.5 Far-infraredlines:theboronisoelectronicsequence 191
9 Absorptionlinesandradiativetransfer 194
9.1 Opticaldepthandcolumndensity 194
9.2 Linebroadening 195
9.3 Absorptionlines 205
9.4 Radiativetransfer 209
9.5 LTEandnon-LTE 216
10 Stellarpropertiesandspectra 220
10.1 Luminosity 220
10.2 Spectralclassification–HRdiagram 221
10.3 Stellarpopulation–massandage 224
10.4 Distancesandmagnitudes 225
10.5 Colour,extinctionandreddening 225
10.6 Stellarstructureandevolution 226
10.7 High-Z elements 231
10.8 Atmospheres 231
10.9 Solarspectroscopy 232
10.10 Coolandhotstars 236
10.11 Luminousbluevariables 237
11 Opacityandradiativeforces 239
11.1 Radiativeandconvectiveenvelope 239
11.2 Equationsofstellarstructure 240
11.3 Radiativefluxanddiffusion 241
11.4 Opacity 243
11.5 Radiativeforcesandlevitation 252
11.6 Opacitiesandaccelerationsdatabase 255
12 GaseousnebulaeandHIIregions 257
12.1 Diffuseandplanetarynebulae 257
12.2 Physicalmodelandatomicspecies 257
12.3 Ionizationstructure 259
12.4 Spectraldiagnostics 261
12.5 Fluorescentphoto-excitation 272
12.6 Abundanceanalysis 275
12.7 Atomicparametersfornebularemissionlines 277
13 Activegalacticnucleiandquasars 278
13.1 Morphology,energeticsandspectra 279
13.2 Spectralcharacteristics 288
13.3 Narrow-lineregion 290
13.4 Broad-lineregion 291
13.5 FeIIspectralformation 291
13.6 Thecentralengine–X-rayspectroscopy 295
viii Contents
14 Cosmology 305
14.1 Hubbleexpansion 306
14.2 Recombinationepoch 307
14.3 ReionizationandLyαforests 308
14.4 CMBanisotropy 310
14.5 Heliumabundance 312
14.6 Darkmatter:warm–hotintergalacticmedium 313
14.7 Timevariationoffundamentalconstants 314
14.8 Thedistancescale 316
AppendixA Periodictable 324
AppendixB Physicalconstants 325
AppendixC Angularalgebraandgeneralizedradiativetransitions 328
AppendixD CoefficientsofthefinestructurecomponentsofanLSmultiplet 333
AppendixE EffectivecollisionstrengthsandA-values 337
References 348
Index 357