Ground-based Exoplanet Atmospheres Characterization:

Progress Since the 2009 Breakthrough

Mercedes López-MoralesCarnegie Institution of Washington

Hubble Fellows Symposium 2010

Collaborators: Daniel Apai (STScI), David Sing (Exeter, UK), Sara Seager (MIT), Justin Rogers (JHU/CIW), Adam Burrows (Princeton), Jeff Coughlin (NMSU), Michael Sterzik (ESO)

Nov 1995: discovery of51 Pegasi b by Mayor &Queloz; confirmed by Marcy & Butler on December 1995.

Star’s Spectral Type: G2VMp sin i = 0.468 Mjup; P = 4.23077 day

March 2010: more than 400 discovered.

Finding Earth-mass planets

Atmospheric characterization

How can we measure an exoplanet’s atmosphere?

Direct Imaging

Transits

Primary Eclipse

Secondary Eclipse

Primary eclipse (~ 1% of total light)

Secondary eclipse(< 0.1 - 0.2% of total light)

Real data for HD 189733b (Knutson et al. 2007)

Primary Eclipses: Transmission Spectra

Secondary Eclipses: Emission spectra

Showman & Guillot 2002López-Morales & Seager 2007

;

(Tinetti et al. 2007)Exoplanet atm

osphere’s spectrum

Sodium (HD 209458b)(Charbonneau et al. 2002)

HST/STIS

Secondary @ 24 μm (HD 209458b)(Deming et al. 2005)

Spitzer/MIPS

First exoplanet atmosphere detections

Results from the ground

6.5-m Magellan

3.5-m APO

8.0-m VLT

4.2-m WHT

+ HET, Subaru, IRTF

Primary Eclipses: Transmission Spectra

Ground-based detection of Sodium in HD 189733b (Redfield et al. 2008)

> 3 detection

Ground-based confirmation of Sodium in HD 209458b (Snellen et al. 2008)

= 3.0 Å Depth = 0.056%

= 0.75 Å Depth = 0.135%

> 5 detection

Secondary Eclipse: Thermal + Reflected Emission

Ogle-TR-56b(Sing & López-Morales 2009) (de Mooij & Snellen 2009)TrES-3b

z’-band (0.9 m) Depth = 0.036% (3.6)

K-band (2.2 m) Depth = 0.241% (~6)

8-m VLT + 6.5-m Magellan

4.5-m WHT

Tz’ = 2718 ± 120 KAB ~ 0.0 (no-clouds)f ~ 0.56 (low winds)

Thermal Inversion

TK = 2040 ± 185 KAB ~ 0.0 (no-clouds)f ~ 2/3 (low winds)

Thermal Inversion

Secondary Eclipse: Thermal + Reflected EmissionCoRoT-1b(Gillon et al. 2009)

HJD (days)NB2090 (2.09 m) Depth = 0.278% (~5) Ks-band (2.2 m) Depth = 0.324% (7.7)

8-m VLT 3.5-m APO

(Rogers et al. 2009)

(Rogers et al. 2009)

Tz’ = 2460 (+80/-160) KAB ~ 0.00 (+0.08/-0.00)f ~ 0.52 (+0.07/-0.08)

Heat

Red

istrib

utio

n Fa

ctor

(f)

Bond Albedo AB

Bond Albedo AB

Flux

Fν

[ Jy

]

Prominent dT between day and night sides

** Atmospheric models generated by co-author A. Burrows

Secondary Eclipse: Thermal + Reflected Emission

(Rogers et al. 2009)

- Models for different f (Pn) and extra-absorber opacities κe

-The extra-absorber is at Pheight = 1 mbar

- Models reproduce emission in the optical, but near-IR emission is twice larger than predicted.

- Attempt to reproduce the near- IR emission using Pn = 0.1 and extra-absorber with κe = 0.05 cm2g-1 at Pheight = 10 mbar

- Models still cannot reproduce near-IR emission.

WASP-12b(López-Morales et al. 2010)

Secondary Eclipse: Thermal + Reflected Emission

z’-band (0.9 m) Depth = 0.082% (5.4)

-The measured z’-band depth fits well BB models and atmospheric models with and w/o thermal inversions. Need more λ’s.

Eclipse’s central phase = 0.5100 ± 0.0022

e |cosω| = 0.0156 ± 0.0035e = 0.057 ± 0.013 (assuming ω = 74°)

(Hebb et al. 2009)

3.5-m APO

Secondary Eclipse: Thermal + Reflected EmissionWASP-19b (Anderson et al. 2010) (Gibson et al. 2010)

H-band (1.62 m) Depth = 0.259% (~5.7) NB2090 (2.09 m) Depth = 0.366% (~5)

8-m VLT 8-m VLT

-The hottest possible models cannot reproduce the H-band depth.- The 2.09 m atmosphere is slightly better reproduced, but still ~ 1-sigma brighter than the models.

HD 189733b(Swain et al. 2010)

Depth > 1.0%(>10)

Secondary Eclipse: Spectro-photometry

- Day-side observations between 2.0 – 2.4 μm and 3.0 – 4.1 μm

- Spectro-photometry with R= 470

Eclipse depths agree when compared to available HST and Spitzer data.

Secondary Eclipse: SpectrophotometryHD 189733b(Swain et al. 2010)

LTE models OK

Non-LTE?

Conclusions• We have now observed the atmospheres of 7 Hot Jupiters from the ground:

transmission NaI D signals of 2 planets in 2008 emission photometry of 5 planets in 2009-2010 spectro-photometry of 1 exoplanet in 2010• For CoRoT-1b we can now assure that AB ~ 0 and the

planet does have a much hotter day-side than night-side (thermal inversion layer)

hints of the same behavior in other planets, but need more color measurements

• Previously untested models seem to have problems reproducing the emission of some hot Jupiters in the near-IR. Non-LTE??• Observational improvements in the next few years will be aimed at studying the atmospheres of the first transiting exo-Earths