L04 - 1/19/12 ImportantNo/ce 1stQuizonJan26(1weekfromtoday)

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Unformatted text preview: 1/19/12 ImportantNo/ce 1stQuizonJan26(1weekfromtoday) about10~15problems mul/plechoice+T,F+answering +simplemath? itwillcoverChap0.2. Tipsforstudyingthetextbook. Exoplanets 51Pegasib *1stexoplanetdiscovered (1995)orbi/ngaSunlikestar CentralStar(51Pegasi) Mass,Temperaturearevery similartoSun 51Pegasib CloudyhotJupiter sizeofJupiter R=0.05AU P=4days Howcouldthismassiveplanet existinsucha/ghtorbit? Thisisatotallyunexpected nature! 1 1/19/12 Kepler10b,1stRockyexoplanet Verydenseplanet =8.8g/cm3 Densityisoneofimportantphysical parametersofexoplanet. Howdowemeasuredensity? Density=mass/volume[g/cm3] Measuremass&sizeof Hoststar>>thisgivesus thetruesizeoftheplanet! Measurethemassof planetusingwobbling mo/on Rela/vesizeofplanet fromthelightcurve Calculatedensity e.g.densityofwater =1g/cm3 Kepler16b,exoplanetorbi/ngaroundabinarysystem R=0.7AU P=229days M=0.3MJ r=0.7rj(Saturnsize) =0.9g/cm3(itfloats!) Didwediscover"Tatooine"? 2 1/19/12 Howroman/cisthatyouhavetwosunsatsunset! MulAplememberexoplanetarysystem R~1AU P=260days Ifthereexistrockymoons aroundthisplanet,itmight havepoolofliquidwaterto supportlifeforms! 3 1/19/12 EuropawouldbeawaterworldifJupiter isorbi/ngSunattheEarthorbit! ThisiswhereSiFimovies getsomeidea! Pandora,theHomeofNavi,oneofmoonsofPolyphemus Movie vs Facts ThisisactualPandora! PolyphemusisaJupiterlikeplanet orbi/ng(SF)aroundAlphaCentauriA whichisthemostcloseststarfrom Sun(Fact,D~4.36lyr) The1stEarthlikeexoplanetorbi/ngaSunlikestarwithinHabitableZone! 4 1/19/12 Let'sputitalltogether. Thegeneralproper/esofthe exoplanetarysystems. GeneralProper/esofKnowExoplanets 1.Mass Exoplanetsappeartobe moremassivethanEarth (It'sispar*allyduetothe limita*oninourcurrent detec*ontechnology) Themajorityofmassesis popula/ngaroundMJ GeneralProper/esofKnowExoplanets 2.OrbitalShape(i.e.Eccentricity) Many exoplanets have Highly eccentric orbits This is clearly different from the orbital property of our Solar System e.g.eccentricityofEarthorbit=0.02 5 1/19/12 GeneralProper/esofKnowExoplanets 3.DistancefromHostStar Distance from the host stars is ranging from 0.02to 6 AU Exoplanetary systems appear to be more compact than Solar System ! GeneralProper/esofKnowExoplanets 4.Numberofmembers&Layout Relatively small number of members than Solar system (don'tforgetabout ourlimita*on) Totally unexpected layout : Jupiter-like planets inside 1AU? Wereviewedseveralexamplesandthegeneral proper/esoftheexoplanetssofar. Howdoastronomersgettheseinforma/on? Howastronomersdetectexoplanets? 6 1/19/12 SiriusB SiriusA SiriusBisatleast1000/mesfainterthanSiriusA Planetsaregenerallyatleast1000/mesfainterthanSiriusB! ExoplanetDetec/onMethods IndirectMethods RadialVelocity(DopplerShiu) AstrometricMeasurement TransitMethod(LightCurve) Gravita/onalMicrolensing DirectMethod DirectImaging DirectImagingwithAO HR8799System:1stexoplanetsdirectlyimaged GeminiNorth 7 1/19/12 Adap/veOp/cs(AO) EarthAtmospheredistortsthelight paxernsfromsources. AOtechniquedeformsthesurface ofmirrorundercomputercontrol duringobserva/ontoremovethe effectsofatmospherictubulence. AOon AOoff 8 ...
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