Climate and radiative properties of a tidally-locked …...Climate and radiative properties of a tidally-locked planet around Proxima Centauri 10/10/18 ESA M4 ARIEL-IT Meeting 2018

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

10/10/18 ESAM4ARIEL-ITMeeting2018 3

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.


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


Acasestudy:Proximab

Anglada-Escudé,G.etal.,2016

European Southern ObservatoryHigh Accuracy Radial velocity Planet Searcher and

Ultraviolet and Visual Echelle Spectrograph Intruments


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)


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/

.


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


] 𝐹 _àb_ca 𝜆ef

ea𝑑𝜆 ] 𝐹 _àb_ 𝜆

ef

ea𝑑𝜆 ] 𝐹 _àb_à 𝜆

ef

ea𝑑𝜆

] 𝐹 _b_ca 𝜆ef

ea𝑑𝜆 ] 𝐹 _b_ 𝜆

ef

ea𝑑𝜆 ] 𝐹 _b_à 𝜆

ef

ea𝑑𝜆

] 𝐹 _cab_ca 𝜆ef

ea𝑑𝜆 ] 𝐹 _cab_ 𝜆

ef

ea𝑑𝜆 ] 𝐹 _cab_à 𝜆

ef

ea𝑑𝜆

Planetthermal flux

𝐹 ,b 𝜆

Planetreflectionspectra

AIRSbroad-bands

1.95 − 3.90𝜇𝑚

3.90 − 7.80𝜇𝑚

Results: Synthetic spectra


Superrotation

Results: Atmosphere/climate detectability

A0StarG2StarM5Star

Earth-likeplanet


Results: PlaSim +libRadtran outputIntegrated flux ratio 23.5– 27.5μm


Simulateanobservation:

• Fromspace withtheMid-Infrared Imager ontheJamesWebb SpaceTelescope

• Fromground based instruments byphotometry intheEarth’s atmospheric windows


JamesWebb SpaceTelescope – MediumInfrared InstrumentImager (MIRIM)

MIRIMinputfieldofview FULL = 1024 × 1024;BRIGHTSKY = 512 × 512;SUB256 = 256 × 256;SUB128 = 128 × 136;SUB64 = 64 × 72


Specularby

symmetry

Not face-on

Not face-on

Non-transiting

JWSTMIRIM– Filters andrelativesignalamplitude


JamesWebb SpaceTelescopeExposureTimeCalculatorhttps://jwst.etc.stsci.edu/

Orbital period

11.186Earth’s days

ExposureTime

5hours


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


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


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



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


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


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


RESULTSCheckforsystemsteadystate

Dynamics


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⁄


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


Documents

Climate and radiative properties of a tidally-locked …...Climate and radiative properties of a tidally-locked planet around Proxima Centauri 10/10/18 ESA M4 ARIEL-IT Meeting 2018