Carbon- rich Exoplanets

Transcription

1 Carbon- rich Exoplanets Nikku Madhusudhan Princeton University Exploring Strange New Worlds: From Giant Planets to Super Earths Flagstaff, AZ. May 04, 2011

2 Overview 1. WASP-12b and the need for a second dimension for atmospheric characterization of exoplanets" 2. The new territory of carbon-rich (C/O > 1) planets: formation, interiors, atmospheres" 3. New observations in the pre-jwst era"

3 Surprises in the dayside atmosphere of hot Jupiter WASP- 12b A high C/O raho and weak thermal inversion in the atmosphere of exoplanet WASP- 12b Nikku Madhusudhan (MIT/Princeton), Joseph Harrington (UCF), Kevin Stevenson (UCF), Sarah Nymeyer (UCF), Christopher Campo (UCF), Peter Wheatley (WASP), Drake Deming (NASA GSFC), Jasmina Blecic (UCF), Ryan Hardy (UCF), Nate Lust (UCF), David Anderson (WASP), Andrew Collier- Cameron (WASP), Christopher BriV (UCF), William Bowman (UCF), Leslie Hebb (WASP), Coel Hellier (WASP), Pierre Maxted (WASP), Don Pollacco (WASP), Richard West (WASP), 2011, Nature, 64, 469

4 WASP- 12b Seager et al Image credit: NASA/JPL- Caltech

5 Two TheoreHcal ExpectaHons for WASP- 12b WASP- 12b 1. Strong thermal inversion Incident Flux (ergs s - 1 cm - 2 ) 2. Abundant H 2 O, scarce CH 4 Planet Gravity (cm s - 2 ) Hubeny et al. (2003), Fortney et al. (2008), Madhusudhan & Seager (2010, 2011) (but cf. Spiegel et al. 2009; Knutson et al. 2010)

6 ObservaHons of Thermal Emission Croll et al. (2011) Campo et al. (2011) López- Morales et al. (2010)

7 ExploraHon of Atmospheric Phase Space Madhusudhan et al. 2011, Nature, 469, 64 Atmospheric Retrieval Technique Grid- based: (Madhusudhan & Seager, 2009) Bayesian: (Madhusudhan & Seager, 2010 & 2011)

8 No Evidence for a Strong Thermal Inversion ξ 2 = Χ 2 /N obs > 4 Madhusudhan et al. 2011, Nature, 469, 64

9 A Carbon- rich Atmosphere Key Molecular Constraints H 2 O/H CH 4 /H C/O 1 ξ 2 = Χ 2 /N obs Madhusudhan et al. 2011, Nature, 469, 64 > 4

10 Spectral Fits to ObservaHons Madhusudhan et al. 2011, Nature, 469, 64

11 Need for a Second Dimension

12 Follow- up Required!! New observahons are crihcal to confirm the C/O>1. New absorbers that we haven t thought about. Atmospheric Variability in WASP- 12b. Does the atmospheric composihon of WASP- 12b reflect its interior composihon? Photochemistry?

13 !"!)$(&!"!+$*&!"!+,(&!"!()*&!"!$*(&!"''%& %"'(-.!+&!"#$%& /0& /0'& 12+& 2'3& 1'& /2+02& /2#& 42+& Madhusudhan et al. (in prep) Torrence Johnson (Talk + Poster) Planet FormaHon Roberge et al C/O = 9 Beta Pictoris (Credits: ESO) Kuchner & Seager (2005), Bond et al. (2010) Planetesimals depleted in water ice Carbide and pure carbon based interiors Interiors Carbon- rich Planets Paucity of water vapour, abundant hydrocarbons, weak inversions Jean- Charles Augereau (Talk) Atmospheres

14 CRP spectra Madhusudhan et al. (in prep)

15 ObservaHonal Constraints NEED NEW GROUND BASED DATA

16 ComparaHve Study of Exoplanet Atmospheres HD b TrES 2 HAT- P- 7b O Donovan et al Charbonneau et al Grillmair et al Swain et al ChrisHansen et al Madhusudhan & Seager, 2009 HD b Knutson et al Madhusudhan & Seager, 2009 GJ 436b Stevenson et al TrES- 4 Knutson et al Madhusudhan & Seager, 2010 HD b, HD b, TrES- 2, TrES- 4, HAT- P- 7b, WASP- 18b, WASP- 14b, WASP- 12b, HD , GJ 436b, Kepler- 5b, 6b, 7b,

17 Cloudy Atmospheres

18 HR 8799b: Cloud- free models Madhusudhan, Burrows, & Currie, 2011 (submived, arxiv: )

19 Cloudy Models Madhusudhan, Burrows, & Currie, 2011 (submived, arxiv: )

20 Thick Cloud Models for HR 8799 b,c,d Madhusudhan, Burrows, & Currie (2011), Currie et al Also see Barman et al. (2011) Marley et al. (2011)

21 Summary 1. The C/O ratio offers a second dimension for atmospheric characterization of exoplanets." 2. Carbon-rich (C/O > 1) planets present a new territory in planetary formation, interiors, and atmospheres." 3. Near-IR observations with current instruments have immense potential to constrain C/O ratios in the pre-jwst era. "

22 "NASA's Spitzer Reveals First Carbon- Rich Planet" - NASA/JPL News WASP- 12b The Most Fanciful Planet Ever! Time Magazine 'Diamond exoplanet' idea boosted by telescope find BBC "Scorching Hot Alien Planet Abounds With Carbon Space.com Exoplanet Strikes Carbon Pay Dirt ScienHfic American Carbon- Rich Planet: A Girl's Best Friend? US News Carbon is King on a Hot Jupiter Sky & Telescope "Astronomen staunen über zwei ferne Exoten Der Spiegel