IRSF SIRIUS JHKs Simultaneous Transit Photometry of GJ1214b

We report high precision transit photometry of GJ1214b in JHKs bands taken simultaneously with the SIRIUS camera on the IRSF 1.4m telescope at Sutherland, South Africa. Our MCMC analyses show that the observed planet-to-star radius ratios in JHKs bands are R_{\rm p}/R_{\rm s,J} = 0.11833 \pm 0.00077, R_{\rm p}/R_{\rm s,H} = 0.11522 \pm 0.00079, R_{\rm p}/R_{\rm s,Ks} = 0.11459 \pm 0.00099, respectively. The radius ratios are well consistent with the previous studies by Bean et al. (2011) within 1\sigma, while our result in Ks band is shallower than and inconsistent at 4\sigma\ level with the previous measurements in the same band by Croll et al. (2011). We have no good explanation for this discrepancy at this point. Our overall results support a flat transmission spectrum in the observed bands, which can be explained by a water-dominated atmosphere or an atmosphere with extensive high-altitude clouds or haze. To solve the discrepancy of the radius ratios and to discriminate a definitive atmosphere model for GJ1214b in the future, further transit observations around Ks band would be especially important.

[1]  M. Ikoma,et al.  IN SITU ACCRETION OF HYDROGEN-RICH ATMOSPHERES ON SHORT-PERIOD SUPER-EARTHS: IMPLICATIONS FOR THE KEPLER-11 PLANETS , 2012, 1204.5302.

[2]  Jacob L. Bean,et al.  A ground-based transmission spectrum of the super-Earth exoplanet GJ 1214b , 2010, Nature.

[3]  L. Koesterke,et al.  Sodium Absorption from the Exoplanetary Atmosphere of HD 189733b Detected in the Optical Transmission Spectrum , 2007, 0712.0761.

[4]  R. P. Butler,et al.  Measurement of Spin-Orbit Alignment in an Extrasolar Planetary System , 2005, astro-ph/0504555.

[5]  D. Ehrenreich,et al.  SEARCH FOR CARBON MONOXIDE IN THE ATMOSPHERE OF THE TRANSITING EXOPLANET HD 189733b , 2009, 0903.3405.

[6]  Akihiko Fukui,et al.  Erratum: Measurements of Transit Timing Variations for WASP-5b , 2010, 1009.5769.

[7]  John Southworth,et al.  Homogeneous studies of transiting extrasolar planets – I. Light-curve analyses , 2008, 0802.3764.

[8]  S. Albrecht,et al.  Ground-based detection of sodium in the transmission spectrum of exoplanet HD209458b , 2008, 0805.0789.

[9]  A. Moorwood,et al.  Instrument Design and Performance for Optical/Infrared Ground-based Telescopes, , 2003 .

[10]  Princeton,et al.  Theoretical Transmission Spectra during Extrasolar Giant Planet Transits , 1999, astro-ph/9912241.

[11]  Yasuhiro Ohta,et al.  PREDICTING PHOTOMETRIC AND SPECTROSCOPIC SIGNATURES OF RINGS AROUND TRANSITING EXTRASOLAR PLANETS , 2006, astro-ph/0611466.

[12]  R. Gilliland,et al.  Detection of an Extrasolar Planet Atmosphere , 2001, astro-ph/0111544.

[13]  J. Fortney,et al.  THE NATURE OF THE ATMOSPHERE OF THE TRANSITING SUPER-EARTH GJ 1214b , 2010, 1001.0976.

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

[15]  S. Ida,et al.  N-BODY SIMULATIONS OF PLANETARY ACCRETION AROUND M DWARF STARS , 2009, 0904.4543.

[16]  R. Redmer,et al.  THERMAL EVOLUTION AND STRUCTURE MODELS OF THE TRANSITING SUPER-EARTH GJ 1214b , 2010, 1010.0277.

[17]  J. Winn,et al.  IMPROVED MODELING OF THE ROSSITER–McLAUGHLIN EFFECT FOR TRANSITING EXOPLANETS , 2011, 1108.4430.

[18]  M. Tamura,et al.  Subaru HDS transmission spectroscopy of the transiting extrasolar planet HD 209458b , 2005, astro-ph/0504540.

[19]  S. Bloemen,et al.  Gravity and limb-darkening coefficients for the Kepler, CoRoT, Spitzer, uvby, UBVRIJHK, and Sloan photometric systems , 2011 .

[20]  Joab R Winkler,et al.  Numerical recipes in C: The art of scientific computing, second edition , 1993 .

[21]  Joshua N. Winn,et al.  THE TRANSIT LIGHT CURVE PROJECT. XIII. SIXTEEN TRANSITS OF THE SUPER-EARTH GJ 1214b , 2010, 1012.0376.

[22]  David Charbonneau,et al.  THE GJ1214 SUPER-EARTH SYSTEM: STELLAR VARIABILITY, NEW TRANSITS, AND A SEARCH FOR ADDITIONAL PLANETS , 2010, 1012.0518.

[23]  C. Moutou,et al.  Misaligned spin-orbit in the XO-3 planetary system?† , 2008, Proceedings of the International Astronomical Union.

[24]  J. Fortney,et al.  THE FLAT TRANSMISSION SPECTRUM OF THE SUPER-EARTH GJ1214b FROM WIDE FIELD CAMERA 3 ON THE HUBBLE SPACE TELESCOPE , 2011, 1111.5621.

[25]  D. Ehrenreich,et al.  Transit spectrophotometry of the exoplanet HD 189733b - II. New Spitzer observations at 3.6 μm , 2010, 1008.2481.

[26]  D. Rubin,et al.  Inference from Iterative Simulation Using Multiple Sequences , 1992 .

[27]  Sara Seager,et al.  THE OPTICAL AND NEAR-INFRARED TRANSMISSION SPECTRUM OF THE SUPER-EARTH GJ 1214b: FURTHER EVIDENCE FOR A METAL-RICH ATMOSPHERE , 2011, 1109.0582.

[28]  Xavier Bonfils,et al.  A super-Earth transiting a nearby low-mass star , 2009, Nature.

[29]  Diana Valencia,et al.  Detailed Models of Super-Earths: How Well Can We Infer Bulk Properties? , 2007, 0704.3454.

[30]  J. Fortney,et al.  OBSERVATIONAL EVIDENCE FOR A METAL-RICH ATMOSPHERE ON THE SUPER-EARTH GJ1214b , 2011, 1103.2370.

[31]  W. Ward.  Density waves in the solar nebula: Diffential Lindblad torque , 1986 .

[32]  R. P. Butler,et al.  OBLIQUITIES OF HOT JUPITER HOST STARS: EVIDENCE FOR TIDAL INTERACTIONS AND PRIMORDIAL MISALIGNMENTS , 2012, 1206.6105.

[33]  A. Triaud.  The time dependence of hot Jupiters' orbital inclinations , 2011, 1109.5813.

[34]  A. Burrows,et al.  THEORETICAL TRANSIT SPECTRA FOR GJ 1214b AND OTHER “SUPER-EARTHS” , 2012, 1203.1921.

[35]  Gautam Vasisht,et al.  The presence of methane in the atmosphere of an extrasolar planet , 2008, Nature.

[36]  J. Koppenhoefer,et al.  Optical to near-infrared transit observations of super-Earth GJ 1214b: water-world or mini-Neptune? , 2011, 1111.2628.

[37]  Motohide Tamura,et al.  First Evidence of a Retrograde Orbit of a Transiting Exoplanet HAT-P-7b , 2009, 0908.1673.

[38]  Y. Ohta,et al.  Measurement of the Rossiter–McLaughlin Effect in the Transiting Exoplanetary System TrES-1 , 2007, astro-ph/0702707.

[39]  E. Turner,et al.  A search for Hα absorption in the exosphere of the transiting extrasolar planet HD 209458b , 2004, astro-ph/0404469.

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

[41]  S. Seager,et al.  THREE POSSIBLE ORIGINS FOR THE GAS LAYER ON GJ 1214b , 2009, 0912.3243.

[42]  Norman Murray,et al.  BROADBAND TRANSMISSION SPECTROSCOPY OF THE SUPER-EARTH GJ 1214b SUGGESTS A LOW MEAN MOLECULAR WEIGHT ATMOSPHERE , 2011, 1104.0011.

[43]  N. Gibson,et al.  Hubble Space Telescope transmission spectroscopy of the exoplanet HD 189733b: high‐altitude atmospheric haze in the optical and near‐ultraviolet with STIS , 2011, 1103.0026.