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Beforewestart
Briefintroduc-onoftheplansandideasfortheplanetarygroup(LinkswithChileanUniversi-esJC/OneDayWS;PlanetarySystemsII)
Visitorsencouraged
Memberstoprovidecross‐trainingtoPAOmembers(PAOisaplacetotalkaboutscience!PlanetsisakeydriverforthefutureofESO,weshouldtogrowexper-seandinterestonthefield)
Frequencyofthemee-ngs–Everytwoweeksseemsagoodnumber
Spin‐orbitanglemeasurementsforsixsoutherntransitingplanetsAmauryTriaudetal
http://www.superwasp.org/documents/triaud2010_rossiter.pdf
“Thisisarealbombwearedroppingintothefieldofexoplanets,”saysAmauryTriaud,aPhDstudentattheGenevaObservatorywho,withAndrewCameronandDidierQueloz,leadsamajorpartoftheobserva-onalcampaign.
WHY???
Rossiter‐McLaughlineffect
Howaboutthespectroscopictransit?
Weallknowhowaphotometrictransitlookslike
Radialvelocity
Thetransi/ngobjectblocksthestellardiskproducingashi:intheRV
Theamplitudeofthiseffectisrelatedtothegeometryandtotherota/onalvelocity
Ohtaetal.(2005)
Ohtaetal.(2005)
Thus:
• forβ=0theplanetaryorbitisperpendiculartothestellarrota/onaxis;• Forβ=90theorbitisalongtherota/onaxis
• Forβ>90theorbitalmo/onisretrograde
λ(orβ inTriaud’spaper)istheprojectedspinorbitmisalignmentangle.
Gaudi&Winn2006,ApJ
Measurements
Globalfiangofphotometrictransit,RVcurveandspectroscopictransit
6transi-ngplanetsfoundbyWASPwerestudiedinthepaper
3ofthemhaveβ>90(retrogradeorbits)
3othershaveβ~0
WASP‐15b;β=139 WASP‐5b;β~0
AmauryTriaudetal
Therealmisalignment
Theymeasuredthesky‐projectedspin‐orbitangle
Therealangleψ ises-matedusingtheargumentthatthespinaxisisisotropicallydistributed
cosψ=cosIcosi+sinIcosβ
Iistheinclina-onofthestellarspinaxisandItheinclina-onoftheplanet’sorbitalaxis.
AmauryTriaudetal
Discussion
26RMeffectshavebeenobservedsofar
14haveβ<22andareconsideredaligned
Theyfindthatthereisa82%probabilitythatψis>22deg(SolarSystemcase)
AmauryTriaudetal
KozaiMechanism
Inapresenceofa3rddistantbody,iftheorbitalplaneoftheinnerbinaryisnotalignedwiththeouterorbit,thee_inandtheinclina-onbetweenthetwoorbitswilloscillateincycles.
KC+Tidalfric-onthee_inbecomeslargesothatintheperiastronpassage-destakeoverforawhileworkingtowardsacircularorbit.
Theoreticalprediction
Thepredic-onforthemisalignmentspin‐planetaryorbitForsystemswithathirdcompanion.(FabryckyandTremaine2007)
Itmatchesbeau-fullytheobserva-ons!
Conclusions
RMmeasurementsobtainedwithhighaccuracyRVdatasuggestthat>80%ofthehot‐jupitersaremisalignedwithanglessome-mes>90%
Forma-onofhot‐jupitersviamigra-onrequiresinterac-onswiththediscandthereforecoplanarity
Kozaimechanismwouldcausetheinnerorbittooscillate(e_in,inclina-on)andreducetheorbitalperiod.
Thepredicteddistribu-onofspin‐orbitangleisverysimilartotheonedrawnfromsta-s-calargumentstransformingtheβdistribu-on.