Climate and radiative properties of a tidally-locked …...Climate and radiative properties of a...
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Climateandradiativepropertiesofatidally-lockedplanetaroundProximaCentauri
110/10/18 ESAM4ARIEL-ITMeeting2018
D.Galuzzo1,2 L.Giovannelli1F.Berrilli1 F.Fierli2C.Cagnazzo2
1– DepartmentofPhysics,University ofRome‘TorVergata’
2– IstitutodiScienzedell’AtmosferaedelClima(ISAC),CentroNazionaledelleRicerche(CNR)
UVnewproxiessuitableforStr.O3
UVColor,MgII,UVrecons.,O3 (ML)
UVColorStellarApplication
Climateandpossibleroleofstratosphericozone
UVColorandfluxesin3DGCM(DG)
3DGCM+1DRTM(exoplanets)
Bordi,Berrilli &Pietropaolo,Ann.Geo.,2015
(Exo)planetary-StellarConnection
Earth’sthermosphere
Lovric+,J.SpaceWeatherSpaceClimate,2017Criscuoli+,ApJ,2018
Galuzzo+,ApJ submitted,2018Galuzzo+,J.Climateinpreparation,2018
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Goals
1. Fromsolarandatmospheric physicstoexoplanet climate andstar/planet interactions;
2. Explore awiderangeofparameters forhabitability conditions;
3. Develop aproceduretoassess space andground based detection limits forexoplanets;
4. Supplyamethodtoevaluate therequired performancesoffuturedetectors.
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Why theatmosphere?
• Orbital stability conditions
Habitability Liquidenvironment(Bains,W.,2004)
Water
?
Atmosphere
Noatmosphere
known habitable planets:1
known habitable planets:0
Otherfundamental requirements:
• Characterization ofthecentral star:activityandvariability
Usewhat we learned fromSun andSolarSystem
• Planetary magnetic fields
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Acasestudy:Proximab
Anglada-Escudé,G.etal.,2016
European Southern ObservatoryHigh Accuracy Radial velocity Planet Searcher and
Ultraviolet and Visual Echelle Spectrograph Intruments
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Proximab:derived parameters fromradial velocity(Anglada-Escudé,G.etal.,2016)
Parameter Symbol Value
Orbital period 𝑇 11.186 EarthdaysOrbital semi-majoraxis 𝑎 0.0485AUOrbit eccentricity 𝑒 < 0.35Planetminimummass 𝑚1 1.27𝑀⊕
Eq.blackbody temperature 𝑇67 234𝐾
Planetproperties
Proximab:Unknown planetary parameters(extrapolated forthesimulation)
Parameter Symbol Value
Mean density 𝜌1 𝜌⊕Radius 𝑟1 1.08𝑅⊕Surfacegravity acceleration 𝑔1 10.64𝑚/𝑠?
Axial tilt α 0degRotation rate ω1 6.50×10FG𝑟𝑎𝑑/𝑠
𝑚1 = 𝑀1 sin ι 𝜌⊕ = 5514𝑘𝑔𝑚O
Rotation period = Orbital period(Ribas,I.etal.,2016)
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Hoststarproperties
Stellarproperty Symbol Value
Spectral type - M5.5
Mass 𝑀⋆ 0.120𝑀⊙
Radius 𝑅⋆ 0.154𝑅⊙Bolometric flux 𝐹⋆STU 2.186×10FVV𝑊𝑚F?
Irradiance at PlanetbTOA 𝐹⋆XTY 884.650𝑊𝑚F?
Effective temperature 𝑇⋆6ZZ 3050𝐾
Sun
Sun @1AU
Proxima
Proxima@Planetb
Ribas,I.etal.,2017
Howard,W.S.etal.,2018
a)
b)c)
Proximadatafromhttps://archive.stsci.edu/prepds/muscles/
.
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Simulating anexoplanetary atmosphere
3DIntermediateComplexity GCM 1DRTMPlanetSimulator(PlaSim)
Keplerian parameters
atmospheric composition
surface properties
Libraryforradiativetransfer(libRadtran)
Hoststar
Geometry ofincident radiation
Clouds properties
(Fraedrich,K.etal.,2005) (Emde,C.etal.,2016)
• Earth-like preindustrial atmosphere with360ppm of𝐶𝑂?;
• Stationary vertical profiles forgasses (noseasonal changes),parameterized 𝑂O profile,
taken fromGreen(1980);
• Aquaplanet withaslab thermodynamic ocean of50meters depth;
• Surfacepressureof1000hPa (1000millibars)andtopoftheatmosphere (TOA)fixed at
50hPa.
Simulation initial conditions
North Pole
Dawn zowe
Dusk zone
Anti-stellar point
Sub-stellar point
South Pole
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] 𝐹 _`ab_ca 𝜆ef
ea𝑑𝜆 ] 𝐹 _`ab_ 𝜆
ef
ea𝑑𝜆 ] 𝐹 _`ab_`a 𝜆
ef
ea𝑑𝜆
] 𝐹 _b_ca 𝜆ef
ea𝑑𝜆 ] 𝐹 _b_ 𝜆
ef
ea𝑑𝜆 ] 𝐹 _b_`a 𝜆
ef
ea𝑑𝜆
] 𝐹 _cab_ca 𝜆ef
ea𝑑𝜆 ] 𝐹 _cab_ 𝜆
ef
ea𝑑𝜆 ] 𝐹 _cab_`a 𝜆
ef
ea𝑑𝜆
Planetthermal flux
𝐹 ,b 𝜆
Planetreflectionspectra
AIRSbroad-bands
1.95 − 3.90𝜇𝑚
3.90 − 7.80𝜇𝑚
Results: Synthetic spectra
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Superrotation
Results: Atmosphere/climate detectability
A0StarG2StarM5Star
Earth-likeplanet
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Results: PlaSim +libRadtran outputIntegrated flux ratio 23.5– 27.5μm
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Simulateanobservation:
• Fromspace withtheMid-Infrared Imager ontheJamesWebb SpaceTelescope
• Fromground based instruments byphotometry intheEarth’s atmospheric windows
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JamesWebb SpaceTelescope – MediumInfrared InstrumentImager (MIRIM)
MIRIMinputfieldofview FULL = 1024 × 1024;BRIGHTSKY = 512 × 512;SUB256 = 256 × 256;SUB128 = 128 × 136;SUB64 = 64 × 72
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Specularby
symmetry
Not face-on
Not face-on
Non-transiting
JWSTMIRIM– Filters andrelativesignalamplitude
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JamesWebb SpaceTelescopeExposureTimeCalculatorhttps://jwst.etc.stsci.edu/
Orbital period
11.186Earth’s days
ExposureTime
5hours
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Colorvariation – Groundbased observation simulation
𝑀 −𝑁 = 2.5 logVn𝐹eo
𝐹ep q
𝐹np
𝐹no𝑁 − 𝑄 = 2.5 logVn
𝐹es
𝐹eo q
𝐹no
𝐹ns
ESOIRphotometric passbands
𝑀 = 4.58 ÷ 4.96𝜇𝑚
𝑁 = 8.32 ÷ 13.79𝜇𝑚
𝑄 = 17.05 ÷ 20.28𝜇𝑚
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CONCLUSIONS
• We areable tosimulateatmospheric spectra intheobserving rangeofARIEL.
• Exoplanetclimaticconditionscanbeinferredbyfittingmodelresultstoobservationaldata;
• 3DGCMcanbeused toevaluate theinstrumental observation limits forexoplanets;
• Habitabilitycanbestudiedunderawiderangeofconditions;
• Ongoing collaborationbetween UniToV,ISAC-CNR,UniCal andINAF-IAPStodevelop a3Dradiative,magnetic andparticles modelforplanet/starinteraction;
ANDPERSPECTIVES
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Anglada-Escude,Getal.- Aterrestrialplanetcandidateinatemperateorbitaroundproxima centauri.Nature,536(536),2016.
Bibliography
Bains,W.-Manychemistriescouldbeusedtobuildlivingsystems.Astrobiology,2004
Ribas,I.etal.– ThefullspectralradiativepropertiesofProximaCentauri.A&A,2017
Howard,W.S.etal.– TheFirstNaked-EyeSuperflare DetectedfromProximaCentauri.TheAstrophysicalJournalLetters,2018
Fraedrich,K.etal.- PUMAPortableUniversityModeloftheAtmosphere - WorldDataCenterforClimate(WDCC)atDKRZ,2005
Emde,C.etal.- ThelibRadtran softwarepackageforradiativetransfercalculations(version2.0.1)- Geoscientific ModelDevelopment,2016
Güdel,M.etal.– Flaresfromsmalltolarge:X-rayspectroscopyofProximaCentauriwithXMM-Newton.A&A,2004
VanderBliek,N.S.etal.- InfraredaperturephotometryatESO(1983–1994)anditsfutureuse- Astron.Astrophys.Suppl.Ser.,1996
Ribas,I.etal.– ThehabitabilityofProximaCentaurib- I.Irradiation,rotationandvolatileinventoryfromformationtothepresent.A&A,2016
Green,A.E.S.– AttenuationbyOzoneandtheEarth'sAlbedointheMiddleUltraviolet.OSA,1964
Ressler,M.E.etal.– TheMid-InfraredInstrumentfortheJamesWebbSpaceTelescope,VIII:TheMIRIFocalPlaneSystem,PublicationsoftheAstronomicalSocietyofthePacific,20145
PresentationOverview
• Work’s aims and motivations
• A case study: Proxima b
• Simulating an exoplanetary atmosphere: models
• Method for line-by-line planetary emission spectrum
• Proxima b atmosphere: photometric and spectral features
• Conclusions
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3DNavier-Stokes equations:Conservation ofmomentum:u,v,w
Conservation ofmass:uvuX+ 𝛻 q 𝜌𝐮 = 0
Conservation ofenergy: T,zSimpleradiativescheme
Surface/Sea-ice /oceansubmodels
Spectral transform methodfor non-linear terms
Simulating anexoplanetary atmosphere:PlaSim
Grid-box
Lev𝑛
Lev𝑛 − 1
Lev 0
𝜑| 𝜑|}V𝜑 =longitude (128)𝜃 =latitude (64)
Surface/atmosphereinterface
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Simulating anexoplanetary atmosphere:PlaSim - SimpleRadiation scheme - shortwave
The stellar spectral range is divided into two regions:
Energy flux fractions:
• UV / VIS spectrum, for λ < 0.75 µm: pure clouds
scattering, 𝑂Oabsorption and Rayleigh scattering;
• NIR spectrum, for λ > 0.75 µm: clouds scattering
and absorption, 𝐻?𝑂 absorption.
𝐸V =∫ 𝐹�𝑑λ�an𝐸n
Star spectral flux
𝐸n = ] 𝐹�𝑑λ�
n
𝐸? = 1 − 𝐸V
Sun
𝐸V = 0.51
𝐸? = 0.49
Proxima
𝐸V = 0.23
𝐸? = 0.77
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Methodforline-by-lineplanetary emission spectrum
TOA
Layer 1
Layer 20
p,Tz,r
𝑊𝑚
F?𝑐𝑚
FVFV
ν�
Planetthermal flux𝐸V 𝐸?
Energyinput
libRadtran off-lineradiativetransfer
PlaSim simulation:Planetary atmosphere caratterization
T
𝐶𝑂?
𝑂O
𝐻?𝑂 U
𝐻?𝑂 �
Thermalstructure
Dynamical evolution
λ
𝑊𝑚
F? 𝑛𝑚FV
Stellarinput
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RESULTSCheckforsystemsteadystate
Dynamics
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𝑅T =𝑈𝑓𝐿
𝑓 = 2ω1 sin 𝜃
Results: Dynamics
≪ 1 rotationally dominated atmosphere
⪞ 1 Hadley-celldominated atmosphereψ =
2π𝑟1𝑔1
] [�̅�] cos 𝜃 𝑑𝑝′�
n
Massstreamfunction:
ψ < 0 anticlockwise circulation ψ > 0 clockwisecirculation
𝑈 ∼ 10𝑚 𝑠⁄
𝐿 ∼ 10G𝑚
∼ 10F� sin 𝜃
[#]Showmann,A.P.etal.,ArXive 2010
[#]Showmann,A.P.andPolvani,L.M.,ApJ 2011
[#]Showmann,A.P.etal.,book2013
ψin10G 𝑘𝑔 𝑠⁄
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Results: Dynamics- Superrotation
𝑀Y > 𝑀n
𝑟1 cos 𝜃 𝜔1𝑟1 cos 𝜃 + 𝑢 > 𝜔1𝑟1?
𝑢 > 𝑢�
𝑢� = 𝜔1𝑟1sin 𝜃?
cos 𝜃
Showman,A.P.,etal.,2010&2013
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