NEAR-INFRARED THERMAL EMISSION FROM WASP-12b: DETECTIONS OF THE SECONDARY ECLIPSE IN Ks, H, AND J

We present Ks, H, & J-band photometry of the very highly irradiated hot Jupiter WASP-12b using the Wide-field Infrared Camera on the Canada-France-Hawaii telescope. Our photometry brackets the secondary eclipse of WASP-12b in the Ks and H bands, and in J band starts in mid-eclipse and continues until well after the end of the eclipse. We detect its thermal emission in all three near-infrared bands. Our secondary eclipse depths are 0.309+0.013 ?0.012% in Ks band (24?), 0.176+0.016 ?0.021% in H band (9?), and 0.131+0.027 ?0.029% in J band (4?). All three secondary eclipses are best fit with a consistent phase, , that is compatible with a circular orbit: = 0.4998+0.0008 ?0.0007. The limits on the eccentricity, e, and argument of periastron, ?, of this planet from our photometry alone are thus |ecos ?| < 0.0040. By combining our secondary eclipse times with others published in the literature, as well as the radial-velocity and transit-timing data for this system, we show that there is no evidence that WASP-12b is precessing at a detectable rate and that its orbital eccentricity is likely zero. Our thermal-emission measurements also allow us to constrain the characteristics of the planet's atmosphere; our Ks-band eclipse depth argues strongly in favor of inefficient day to nightside redistribution of heat and a low Bond albedo for this very highly irradiated hot Jupiter. The J- and H-band brightness temperatures are slightly cooler than the Ks-band brightness temperature, and thus hint at the possibility of a modest temperature inversion deep in the atmosphere of WASP-12b; the high-pressure, deep atmospheric layers probed by our J- and H-band observations are likely more homogenized than the higher altitude layer probed by our Ks-band observations. Lastly, our best-fit Ks-band eclipse has a marginally longer duration than would otherwise be expected; this may be tentative evidence for material being tidally stripped from the planet?as was predicted for this system by Li and collaborators, and for which observational confirmation was recently arguably provided by Fossati and collaborators.

[1]  David Lafreniere,et al.  NEAR-INFRARED THERMAL EMISSION FROM THE HOT JUPITER TrES-2b: GROUND-BASED DETECTION OF THE SECONDARY ECLIPSE , 2010, 1005.3027.

[2]  A. Loeb.  A Dynamical Method for Measuring the Masses of Stars with Transiting Planets , 2005, astro-ph/0501548.

[3]  M. López-Morales,et al.  Thermal Emission from Transiting Very Hot Jupiters: Prospects for Ground-based Detection at Optical Wavelengths , 2007, 0708.0822.

[4]  David Charbonneau,et al.  An Upper Limit on the Reflected Light from the Planet Orbiting the Star τ Bootis , 1999, astro-ph/9907195.

[5]  Richard S. Freedman,et al.  A Unified Theory for the Atmospheres of the Hot and Very Hot Jupiters: Two Classes of Irradiated Atmospheres , 2007, 0710.2558.

[6]  I. Hubeny,et al.  A Possible Bifurcation in Atmospheres of Strongly Irradiated Stars and Planets , 2003 .

[7]  I. Hubeny,et al.  Optical Albedo Theory of Strongly Irradiated Giant Planets: The Case of HD 209458b , 2008, 0803.2523.

[8]  A. Collier Cameron,et al.  H-band thermal emission from the 19-h period planet WASP-19b , 2010, 1002.1947.

[9]  E. Agol,et al.  Analytic Light Curves for Planetary Transit Searches , 2002, astro-ph/0210099.

[10]  L. J. Richardson,et al.  On the Dayside Thermal Emission of Hot Jupiters , 2005 .

[11]  Michel Mayor,et al.  The Broadband Infrared Emission Spectrum of the Exoplanet HD 189733b , 2008, 0802.0845.

[12]  D. Saumon,et al.  Atmosphere, Interior, and Evolution of the Metal-rich Transiting Planet HD 149026b , 2006 .

[13]  Tristan Guillot,et al.  Atmospheric circulation and tides of ``51 Pegasus b-like'' planets , 2002 .

[14]  Joseph L. Hora,et al.  Accepted for publication in The Astrophysical Journal Preprint typeset using L ATEX style emulateapj v. 10/09/06 THERMAL EMISSION OF EXOPLANET XO-1B , 2022 .

[15]  R. G. West,et al.  WASP-12b: THE HOTTEST TRANSITING EXTRASOLAR PLANET YET DISCOVERED , 2008, 0812.3240.

[16]  Douglas N. C. Lin,et al.  WASP-12b as a prolate, inflated and disrupting planet from tidal dissipation , 2010, Nature.

[17]  B. Scott Gaudi,et al.  Prospects for the Characterization and Confirmation of Transiting Exoplanets via the Rossiter-McLaughlin Effect , 2006, astro-ph/0608071.

[18]  Mercedes Lopez-Morales,et al.  Ground-based secondary eclipse detection of the very-hot Jupiter OGLE-TR-56b , 2009, 0901.1876.

[19]  Paul S. Smith,et al.  The Multiband Imaging Photometer for Spitzer (MIPS) , 2004 .

[20]  David Lafreniere,et al.  NEAR-INFRARED THERMAL EMISSION FROM TrES-3b: A Ks-BAND DETECTION AND AN H-BAND UPPER LIMIT ON THE DEPTH OF THE SECONDARY ECLIPSE , 2010, 1006.0737.

[21]  Sara Seager,et al.  The Very Low Albedo of an Extrasolar Planet: MOST Space-based Photometry of HD 209458 , 2007, 0711.4111.

[22]  G. Fazio,et al.  The Infrared Array Camera (IRAC) for the Spitzer Space Telescope , 2004, astro-ph/0405616.

[23]  T. Barman.  On the Presence of Water and Global Circulation in the Transiting Planet HD 189733b , 2008, 0802.0854.

[24]  David Charbonneau,et al.  Detection of Thermal Emission from an Extrasolar Planet , 2005 .

[25]  Comparative Planetary Atmospheres: Models of TrES-1 and HD 209458b , 2005, astro-ph/0505359.

[26]  B. Croll.  Markov Chain Monte Carlo Methods Applied to Photometric Spot Modeling , 2006 .

[27]  R. Kuschnig,et al.  WATER, METHANE, AND CARBON DIOXIDE PRESENT IN THE DAYSIDE SPECTRUM OF THE EXOPLANET HD 209458b , 2009, 0908.4010.

[28]  Todd A. Thompson,et al.  Radiation Pressure-supported Starburst Disks and Active Galactic Nucleus Fueling , 2005 .

[29]  Mercedes Lopez-Morales,et al.  DAY-SIDE z′-BAND EMISSION AND ECCENTRICITY OF WASP-12b , 2009, 0912.2359.

[30]  David Charbonneau,et al.  The 3.6-8.0 μm Broadband Emission Spectrum of HD 209458b: Evidence for an Atmospheric Temperature Inversion , 2007, 0709.3984.

[31]  A. Burrows,et al.  DETECTION OF A TEMPERATURE INVERSION IN THE BROADBAND INFRARED EMISSION SPECTRUM OF TrES-4 , 2008, 0810.0021.

[32]  L. Hebb,et al.  A DETAILED SPECTROPOLARIMETRIC ANALYSIS OF THE PLANET-HOSTING STAR WASP-12, , 2010, 1007.3082.

[33]  S. Poddan'y,et al.  Exoplanet Transit Database. Reduction and processing of the photometric data of exoplanet transits , 2009, 0909.2548.

[34]  Drake Deming,et al.  Infrared radiation from an extrasolar planet , 2005, Nature.

[35]  Observatoire de Geneve,et al.  VLT transit and occultation photometry for the bloated planet CoRoT-1b , 2009, 0905.4571.

[36]  A. Liddle,et al.  Information criteria for astrophysical model selection , 2007, astro-ph/0701113.

[37]  Joshua N. Winn,et al.  The Transit Light Curve Project. IX. Evidence for a Smaller Radius of the Exoplanet XO-3b , 2008, 0804.4475.

[38]  Gautam Vasisht,et al.  A ground-based near-infrared emission spectrum of the exoplanet HD 189733b , 2010, Nature.

[39]  Darin Ragozzine,et al.  PROBING THE INTERIORS OF VERY HOT JUPITERS USING TRANSIT LIGHT CURVES , 2008, Proceedings of the International Astronomical Union.

[40]  F. Allard,et al.  The NextGen Model Atmosphere Grid for 3000 ≤ Teff ≤ 10,000 K , 1998, astro-ph/9807286.

[41]  B. Scott Gaudi,et al.  Achieving Better Than 1 Minute Accuracy in the Heliocentric and Barycentric Julian Dates , 2010, 1005.4415.

[42]  Pin Chen,et al.  Submitted to the Astrophysical Journal Letters Molecular Signatures in the Near Infrared Dayside Spectrum of , 2022 .