THE OPTICAL AND NEAR-INFRARED TRANSMISSION SPECTRUM OF THE SUPER-EARTH GJ 1214b: FURTHER EVIDENCE FOR A METAL-RICH ATMOSPHERE

We present an investigation of the transmission spectrum of the 6.5 M⊕ planet GJ 1214b based on new ground-based observations of transits of the planet in the optical and near-infrared, and on previously published data. Observations with the VLT + FORS and Magellan + MMIRS using the technique of multi-object spectroscopy with wide slits yielded new measurements of the planet's transmission spectrum from 0.61 to 0.85 μm, and in the J, H, and K atmospheric windows. We also present a new measurement based on narrow-band photometry centered at 2.09 μm with the VLT + HAWKI. We combined these data with results from a reanalysis of previously published FORS data from 0.78 to 1.00 μm using an improved data reduction algorithm, and previously reported values based on Spitzer data at 3.6 and 4.5 μm. All of the data are consistent with a featureless transmission spectrum for the planet. Our K-band data are inconsistent with the detection of spectral features at these wavelengths reported by Croll and collaborators at the level of 4.1σ. The planet's atmosphere must either have at least 70% H2O by mass or optically thick high-altitude clouds or haze to be consistent with the data.

[1]  M. R. Haas,et al.  PLANET OCCURRENCE WITHIN 0.25 AU OF SOLAR-TYPE STARS FROM KEPLER , 2011, 1103.2541.

[2]  J. Fortney,et al.  THE ATMOSPHERIC CHEMISTRY OF GJ 1214b: PHOTOCHEMISTRY AND CLOUDS , 2011, 1104.5477.

[3]  G. Vasisht,et al.  THERMOCHEMICAL AND PHOTOCHEMICAL KINETICS IN COOLER HYDROGEN-DOMINATED EXTRASOLAR PLANETS: A METHANE-POOR GJ436b? , 2011, 1104.3183.

[4]  T. Barman,et al.  HIGH-RESOLUTION, DIFFERENTIAL, NEAR-INFRARED TRANSMISSION SPECTROSCOPY OF GJ 1214b , 2011, 1104.1173.

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

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

[7]  F. Fressin,et al.  CHARACTERISTICS OF PLANETARY CANDIDATES OBSERVED BY KEPLER. II. ANALYSIS OF THE FIRST FOUR MONTHS OF DATA , 2011, 1102.0541.

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

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

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

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

[12]  David Lafreniere,et al.  NEAR-INFRARED THERMAL EMISSION FROM WASP-12b: DETECTIONS OF THE SECONDARY ECLIPSE IN Ks, H, AND J , 2010, 1009.0071.

[13]  B. Jackson,et al.  RECENT TRANSITS OF THE SUPER-EARTH EXOPLANET GJ 1214b , 2010, 1008.1748.

[14]  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.

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

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

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

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

[19]  S. Seager,et al.  A FRAMEWORK FOR QUANTIFYING THE DEGENERACIES OF EXOPLANET INTERIOR COMPOSITIONS , 2009, 0912.3288.

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

[21]  G. Rupprecht,et al.  Correction of Field Rotator-Induced Flat-Field Systematics—A Case Study Using Archived VLT-FORS Data , 2010, 1001.1099.

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

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

[24]  Mark Casali,et al.  HAWK-I: the high-acuity wide-field K-band imager for the ESO Very Large Telescope , 2008 .

[25]  D. Sasselov,et al.  THE ATMOSPHERIC SIGNATURES OF SUPER-EARTHS: HOW TO DISTINGUISH BETWEEN HYDROGEN-RICH AND HYDROGEN-POOR ATMOSPHERES , 2008, 0808.1902.

[26]  S. Seager,et al.  Ocean Planet or Thick Atmosphere: On the Mass-Radius Relationship for Solid Exoplanets with Massive Atmospheres , 2007, 0710.4941.

[27]  Harland Epps,et al.  MMT and Magellan Infrared Spectrograph , 2004, SPIE Astronomical Telescopes + Instrumentation.

[28]  B. Krauskopf,et al.  Proc of SPIE , 2003 .

[29]  Daniel Durand,et al.  Astronomical Data Analysis Software and Systems XI , 2009 .

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

[31]  David R. Alexander,et al.  The NEXTGEN Model Atmosphere Grid. II. Spherically Symmetric Model Atmospheres for Giant Stars with Effective Temperatures between 3000 and 6800 K , 1999, astro-ph/9907194.

[32]  Robert A. Shaw,et al.  Astronomical data analysis software and systems IV : meeting held at Baltimore, Maryland, 25-28 September 1994 , 1995 .

[33]  E. D. Hoffleit,et al.  The general catalogue of trigonometric [stellar] parallaxes , 1995 .