Detecting molecules in the atmospheres of transit Exoplanets

Giovanna TinettiGiovanna Tinetti

University College LondonUniversity College London

Mao-Chang LiangMao-Chang Liang

Academia Sinica, TaiwanAcademia Sinica, Taiwan

(Schneider)

What’s the Nature of these planets?

>280

Hot-Jupiters are Gas-Giant planets, orbiting VERY close to

their parent star.

They are probably tidally locked, i.e. one face is always

illuminated and the other is in perpetual darkness.

They easily reach Temperatures 1000-2000 K

Hot Jupiter?Hot Jupiter?

The chemistry of Hot-Jupiters The chemistry of Hot-Jupiters C/O ratio = solar C/O ratio = solar

Photochemistry Photochemistry predicted with “predicted with “KineticsKinetics” ” (Liang et al., 2003,2004)(Liang et al., 2003,2004)

Tinetti, Liang, et al., ApjL, 2007

CO & H2O

Following the planet during its orbit

Courtesy of S. Seager

Transiting planets

• Transit [Rp/R*]2 ~ 10-2

– Transit radius

• Emission spectra Tp/T*(Rp/R*)2 ~10-3

– Emitting atmosphere ~2/3– Temperature and T

• Transmission spectra [atm/R*]2 ~10-4

– Upper atmosphere– Exosphere (0.05-0.15)

• Reflection spectra p[Rp/a]2~10-5

– Albedo, phase curve– Scattering atmosphere

Before direct imaging

Spectral signature of a Spectral signature of a transiting planettransiting planet

Star flux

Wavelength

~ 1%

Star flux

Spectral signature of a Spectral signature of a transiting planettransiting planet

Wavelength

~ Rp2/Rs

2

~0,01%

~ 1%

Wavelength

Star flux

Spectral signature of a Spectral signature of a transiting planettransiting planet

~Rp2/Rs2

~Anulus2/Rs2

4.5 hours on October 31, 2006 at 3.6 and 5.8 μm33 hours on November 2, 8 μm

SPITZER OBSERVATIONS

5.8 8 3.6

Star fluxAt 3.6, 5.8 and 8 m,

the planet shows different transit depths:

something is absorbingin its atmosphere!

IRAC observations in the IR,IRAC observations in the IR,primary transit for HD 189733bprimary transit for HD 189733b

~ 0.08%

Tinetti et al., Nature, 448, 163, 2007

Water, T-P ~ 1200 K @ 1 bar, 700 K @ bar

Water line list: BT2

Barber et al., 2006

Tinetti et al., Nature, 448, 163, 2007

T = 500 K

T = 2000 K

Na

K

H2-H2

H2O

Tinetti et al., Nature, 448, 163, 2007

Knutson et al., 2007Winn et al., 2007

Beaulieu et al., 2007

Star spots/hazes?

There is something more….

Beaulieu et al., 2007

Knutson et al., 2007

Swain et al., 2007

Pont et al., 2007

Swain, Vasisht, Tinetti, Nature, 452, 2008

HST-NICMOSPrimary transit

Swain, Vasisht, Tinetti, Nature, 452, 2008

HST-NICMOS HST-NICMOSPrimary transit

Emission spectrum: the day side,Emission spectrum: the day side,water and COwater and CO

Charbonneau et al., 2008; Barman, 2008

HD 189733b: water in absorption

Hot-Jupiters have become a very hot subject, theory and observations are

boosting each-others For thermal structure and chemistry we

have already made the leap to 3D There is a variety of hot-Jupiters, not

only one prototype Primary & secondary transits,

widest possible spectral coverage, spectroscopy and photometry, space & ground based telescopes:

We want them all!

HotHot-Jupite-Jupitersrs

Cavarroc, Cornia, Tinetti, Boccaletti, in preparation

James Webb Space Telescope James Webb Space Telescope performances (MIRI)performances (MIRI)

Planet @ 10, 20, 30 parsec G starG star

Radial velocity / OccultationRadial velocity / Occultation

Period = 3.524738 daysPeriod = 3.524738 days

Mass = 0.69 ±0.05 MMass = 0.69 ±0.05 MJupiterJupiter

Radius = 1.35 ±0.04 RRadius = 1.35 ±0.04 RJupiter Jupiter

DensityDensity = 0.35 ±0.05 g/cm= 0.35 ±0.05 g/cm33

HD 209458bHD 209458b

Primary TransitPrimary TransitStar Flux

Charbonneau et al., 2000

Secondary TransitSecondary TransitStar+Planet Flux

+

Beaulieu et al., ApJ, in press

Knutson et al., Nature, 2007

Primary transit + IR + SpitzerPrimary transit + IR + Spitzer

Emission spectra: thermal profilesEmission spectra: thermal profiles

Knutson et al., 2007; Burrows et al.,2007a,2007b

HD 209458b: water in emission HD 189733b: water in absorption

Burrows et al.,ApJ, 2006

T(K)

Lo

g P

(ba

r)