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1 Extrasolar Planets.I.What do we know and how do we know it.Basic planetary atmospheresSuccessful observations and future plans2Planets Orbiting Other Stars Total:209 discovered to-date.Statistics:Gas giant planets,like Jupiter&Saturn,exist around 12%of stars(Marcy et al.2005);Lower-mass planets (Super-Earths,3 known to-date)are significantly more common (Rivera et al.2005;Beaulieu et al.2006).No Earth-like planets yet3Planets Orbiting Other Stars:after Gould et al.(2006)First Super-Earth discovered GJ 876d:-Mass 7.5 EarthsAlso HD 69830b:-Mass 10 EarthsNASA Kepler mission:Radii in this rangeM=MercuryV=VenusE=Earth,etc.4Atmosphere:In general-outer boundary for planets thermal evolution-the extrasolar planets have introduced conditions never imaginedClouds&(photo)chemistryEvaporation (very hot&hot Jupiters)Transits allow spectroscopic studies of the planets atmosphere5The Close-in Extrasolar Giant PlanetsMacintosh PICTim age form atis not supported Type and size of condensate is important Possibly large reflected light in the optical Thermal emission in the infraredSeager&Sasselov 20006Atmosphere:What is special about atomic Na and the alkali metals?Seager&Sasselov(2000)Macintosh PICTimage formatis not supported7Atmosphere:Theoretical Transmission Spectra of HD 209458 bM a c in to s h P IC Tim a g e fo rm a tis n o t s u p p o rte dWavelength(nm)Occulted Area(%)Seager&Sasselov(2000)8Transmission SpectraM acintosh PICTim age form atis not supportedM a c in to s h P IC Tim a g e fo rm a tis n o t s u p p o rte dH =kT/gmH scale height s sl l extinction cross section L path lengthHow large is the planet atmospheresignal?It depends on theatmosphere annulus/star areaM a c i n t o s h P I C Ti ma g e f o r ma ti s n o t s u p p o r t e d9Atmosphere:The tricks of transmission spectroscopy:Brown(2001)10The actual detection(with the HST):a 5s signal2x weaker than model expected,but within errorsMight indicate high clouds above terminatorCharbonneau et al.(2002)11planet/star flux ratio is:ad M acintosh PICTim age form atis not supportedRpStarPlanetEarthM a c in to s h P IC Tim a g e fo r m a tis n o t s u p p o r te dReflected Lightp is albedoAtmospheric ProbeSudarsky Planet typesI:Ammonia CloudsII:Water CloudsIII:ClearIV:Alkali MetalV:Silicate CloudsPredicted Albedos:IV:0.03V :0.50Sudarsky et al.2000Picture of class IV planet generated using Celestia Software13Photometric Light Curves Micromagnitude variability from planet phase changes Space-based:MOST(2005),COROT(2007),Kepler(2008)D m=2.5(Rp/D)22/3/p(sin()+(p-)cos()M a c i n t o s h P I C Ti m a g e f o r m a ti s n o t s u p p o r t e dSeager et al.200014Scattered Light Need to consider:phase function multiple scattering15Scattered Light Changes with Phase M acintosh P IC Tim age form atis not supportedSeager,Whitney,&Sasselov 200051 Peg 550 nm16Mission q Microvariability and Oscillations of STars/Microvariabilit et Oscillations STellaireq First space satellite dedicated to stellar seismology q Small optical telescope&ultraprecise photometer q goal:few ppm=few micromag MOST at a glance Canadian Space Agency(CSA)17q circular polar orbitq altitude h=820 km q period P=101 minq inclination i=98.6q Sun-synchronousq stays over terminatorq CVZ 54 wide q-18 Decl.+36q stars visible for up to 8 wksq Ground station networkq Toronto,Vancouver,Vienna MOST at a glance MOSTorbit normal vectorto SunCVZ=Continuous Viewing ZoneOrbit Lightcurve Model for HD 209458bRelative depthstransit:2%eclipse:0.005%Duration3 hoursPhase changes of planetPhaseRelative FluxEclipseTransitThe Lightcurve from MOST45 days0.03 mag 2004 data:14 days,4 orbital cycles 2005 data:45 days,12 orbital cyclesduty cycle:90%473 896 observations3 mmag point-to-point precision2005 observations,40 minute binned dataAlbedo ResultsBest fit parameters:Albedo:0.07 0.05stellar radius:1.346 0.005 RJupOther Parameters:stellar mass:1.101 Msuninclination:86.929period:3.52.days see Knutson et al.2006Geometric AlbedoRadius(Jupiter)1,2,3 sigmaerror contoursRowe et al.(in prep)0.1 mag0.02 mag0.8 mmagAtmospheresMOST bandpassGeometric Albedo HD 209458b is darker than Jupiter Rule out class V planet with bright reflection silicon cloudsMarley et al.199923HD 209458b AlbedosNew upperlimit on AgRowe et al.(2006)(Rowe et al.2007)Models Constraints2004 1 sigma limit or-2005 3 sigma limitSpitzer LimitDifferent atmospheresblackbodymodelRowe et al.2006Rowe et al.(in prep)best fitEquilibrium Temperature25Direct SpectrophotometryProposed NASA Mission Nulling coronograph Can image Jupiter-like planets in Earth-like orbits26Direct Spectrophotometry Could observe changing cloud cover and atmospheric conditions on gas giant planets with highly eccentric orbits,like HD 168443.Very exciting unique opportunity to study rates for photochemistry&forcing.27Some of the Hot Jupiters do not match wellmodels based on Jupiter&Saturn:More diversity than expected?.Gaudi(2005)&Charbonneau et al(2006)w Bodenheimer et al.(2003),Laughlin et al.(2005)models;and Burrows et al.(2003)28若有不当之处，请指正，谢谢！
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