Principles of Astrophysics: Using Gravity and Stellar Physics to Explore the Cosmos

444 Pages·2014·8.87 MB·English

by  Charles Keeton (auth.)

Undergraduate Lecture Notes in Physics
Charles Keeton
Principles of
Astrophysics
Using Gravity and Stellar Physics to
Explore the Cosmos
Undergraduate Lecture Notes in Physics
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Charles Keeton
Principles of Astrophysics
Using Gravity and Stellar Physics
to Explore the Cosmos
123
CharlesKeeton
DepartmentofPhysicsandAstronomy
RutgersUniversity
Piscataway,NJ,USA
ISSN2192-4791 ISSN2192-4805(electronic)
ISBN978-1-4614-9235-1 ISBN978-1-4614-9236-8(eBook)
DOI10.1007/978-1-4614-9236-8
SpringerNewYorkHeidelbergDordrechtLondon
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To myparents,who helpedmefind mypath

Preface
Thisbookisdesignedtoshowhowphysicalprinciplescanbeusedattheadvanced
undergraduate level to understand astronomical systems such as planets, stars,
galaxies,andtheuniverseasawhole.ItemergesfromapairofcoursesatRutgers
Universitythatattractnotjustastrophysicsstudentsbutabroadaudienceofphysics
andengineeringstudents.Theorganizationistherefore“physics-first”:westartwith
keyprinciplesofphysicsandthenexamineapplicationstoastronomicalsystems.
AtRutgers,eachhalfofthebookconstitutesacoherentsemester-lengthcourse;
while there is a little overlap (notably with cosmology in Chaps.11 and 20),
the two halves are largely independent and complementary. Part I focuses on
gravity, because this is the dominant force in many astronomical systems and it
governsmanytypesofmotionsweobserve.ThegoalofChaps.2–11istodevelop
a progressively richer understanding of gravity and the way astrophysicists use
gravitationalmotiontoinvestigatemass.
PartIIcentersononeofthe“bigquestions”wehumansask.Whyarewehere?is
admittedlybeyondtherealmofphysics,butarelatedquestioniswithinourreach:
How did we come to be here? As the Sun was forming, various elements came
togetherintherightcombinationtoformarockyplanetwithatenuousatmosphere.
On thisplanetEarth,the energyfromthe Sunandthe gasin theatmospherewere
justrighttoallowtheemergenceoflife.Theenergythatsustainsusoriginatesdeep
insideourstar,thankstoE Dmc2.Theatomsthatcompriseourbodieswereforged
inpreviousgenerationsofstars.Literally,wearestardust.ThegoalofChaps.12–20
istounderstandtherolesthatelectromagnetismaswellasgas,atomic,andnuclear
physicsplayinthisremarkablestory.
I hopethisbookwillhelpyoulearntothinklikean astrophysicist.Rather than
memorizingfacts aboutspecific astronomicalsystems, youwill learn to breakthe
systems into pieces you can analyze and understand using material that should
be familiarfromintroductoryphysicsandvectorcalculus.(The necessaryphysics
topics are reviewed as they arise; vital aspects of vector calculus are reviewed in
AppendixA.)Then youwillbeequippedtoinvestigateinterestingsystemsthatyou
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encounter in the future, even if they are not addressed in this book. Astrophysics
isadynamicfieldofresearch—andoneinwhichyoucanunderstandthephysical
principlesthatunderlieeventhenewestdiscoveries.Solet’shavefun!
Piscataway ChuckKeeton
December2013
Acknowledgements
“Nobookisanisland,entireofitself.”ThatisnotwhatJohnDonneactuallywrote,
but it could have been. It is certainly apt here. This book would not exist in its
presentformwithoutthehelpofmanypeople.
ArthurKosowskyoriginallydevelopedthestructurefortheastrophysicscourses
atRutgers,whichisreflectedinthemakeupofthisbook.SaurabhJha,EricGawiser,
andJohnMoustakashavetaughtfromthismaterialatvariousstagesofdevelopment,
andprovidedcriticalfeedback.Allcontributedideasforhomeworkproblems;and
many rounds of students have (perhaps to their chagrin) field-tested a lot of the
problems.TheRutgersDepartmentofPhysicsandAstronomy,andinparticularthe
astrophysicsgroup,hasprovidedanenvironmentwhereexcellenceinresearchand
teachingarebothencouragedandsupported.
ArtCongdon,AllanMoser,ErikNordgren,BarnabyRowe,andTimJoneshave
done yeomen’swork with the manuscript.They providedextensive and insightful
comments throughout the drafting process, catching everything from typos to
muddledthinking.Allremainingerrorsaremyfault,nottheirs!
Manyresearchershavegraciouslyletmeuseimagesandfigurestoillustratethe
material.Theyaretoonumeroustolisthere,butarecreditedinthefigurecaptions.
A numberof bookshave contributedto my own learning,buttwo in particular
standout.AnIntroductiontoModernAstrophysicsbyBradleyW.CarrollandDale
A. Ostlie is a monumentalsurvey of astrophysics at the undergraduatelevel. The
“big orange book” maintains a respected place on every astronomer’s bookshelf.
AstrophysicsinaNutshellbyDanMaozisamorefocusedtreatisethatsharesalot
of the spirit animating this book.Both have influenced my thinking abouthow to
presentthismaterial,asindicatedthroughoutthetext.
Last but not least, my wife and son have not merely endured this absorbing
project,butactivelyendorsedit.ToKelly:thankyouforlettingmedream.ToEvan:
ifyoucandreamit,youcandoit,butitmighttakemoreeffortthanyouimagine.
This work has received financial support from the U.S. National Science
FoundationthroughgrantAST-0747311.
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