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1、TheH-RDiagramLuminosityClassStarTypeIaluminoussupergiantsTheH-RDiagramIblessluminoussupergiantsIIbrightgiantsIIIgiantsIVsubgiants•MaterialsVmainsequenceComputerProgram:MicrosoftExcelorequivalent•Basics:PlottingandusingExcelHerearesometipsandhintsforplottingyour•Intro
2、ductiondatainExcel.TheintentofthesehintsisnottoThepurposeofthislabistogiveyouahandsteachyouhowtouseExcel.Ifyouhaveques-(andcomputer)onexperiencewiththetions,seeyourinstructor:Hertzprung-Russell,orH-Rdiagram.Asimple1)Convertyourxaxisvaluestonumbers.Forreviewofitschara
3、cteristicswillbegiven.Forexample,setB=0,A=1,etc.Thenyoucanusemoreinformation,pleaseconsultyourtextbook.G2=3.2,orK1=4.1,andsoon.AbasicknowledgeofMicrosoftExcelishelpful.2)InExcel,punchinyournumbersforyourx•Basics:theH-Rdiagramandyaxis.TheH-Rdiagramisaplotoftheabsolute
4、mag-nitudesofstars,M,versustheirspectraltype.3)Makeascatterplot,includingaxislabels.Sometimesyouwillseetheyaxisinunitsofsolarluminosity,L.Luminosityisdirectlypro-4)Togetthecorrectyaxis,withnegativeval-oportionaltoabsolutemagnitude,andinthislab,uesatthetop,clickonthey
5、axisintheplotwewillusetheabsolutemagnitudesofstars.you’vealreadycreated.Goto“Format”,“Se-Remember,themorenegativeanabsolutemag-lectedaxis”,“Scale”tab.Atthebottom,clicknitude,theBRIGHTERthestar.Wewillalsobe“valuesinreverseorder.”usingtheapparentmagnitude,m,ofstars.The
6、SeeyourlabTAifyouhavequestions.apparentmagnitudereferstohowbrightastar•CreateyourH-RdiagramsappearstousonEarth.Thexaxis,spectraltype,isameasureofastar’sA)MainSequenceStarssurfacetemperature.Astronomerslabelspec-Plot,inExceloranothergraphingprogram,thetraltypewithinte
7、gersandletters,rangingfromstarsinTableA.ThecurvethatapproximatelyM10(cool,red),toO0(hot,blue).Notethataconnectsthesepointsisthemainsequence;M7typestariscoolerthanaM0star,andthatmoststarslieonthisline.Asmentionedear-theorderoflettersfromcooltohotis:M,K,G,lier,themains
8、equencestarsareluminosityF,A,B,O.TheSunisaG2starwithsurfaceclassVstars.Makealabelinyourplotthattemperatureofabout5800K.indicatesthi
