CHARACTERIZING THE ATMOSPHERES OF TRANSITING PLANETS WITH A DEDICATED SPACE TELESCOPE

Exoplanetary science is one of the fastest evolving fields of today’s astronomical research, continuously yielding unexpected and surprising results. Ground-based planet-hunting surveys, together with dedicated space missions such as Kepler and CoRoT, are delivering an ever-increasing number of exoplanets, over 690, and ESA’s Gaia mission will escalate the exoplanetary census into the several thousands. The next logical step is the characterization of these new worlds. What is their nature? Why are they as they are? Use of the Hubble Space Telescope and Spitzer Space Telescope to probe the atmospheres of transiting hot, gaseous exoplanets has opened perspectives unimaginable even just 10 years ago, demonstrating that it is indeed possible with current technology to address the ambitious goal of characterizing the atmospheres of these alien worlds. However, these successful measurements have also shown the difficulty of understanding the physics and chemistry of these exotic environments when having to rely on a limited number of observations performed on a handful of objects. To progress substantially in this field, a dedicated facility for exoplanet characterization, able to observe a statistically significant number of planets over time and a broad spectral range will be essential. Additionally, the instrument design (e.g., detector performances, photometric stability) will be tailored to optimize the extraction of the astrophysical signal. In this paper, we analyze the performance and tradeoffs of a 1.2/1.4 m space telescope for exoplanet transit spectroscopy from the visible to the mid-IR. We present the signal-to-noise ratio as a function of integration time and stellar magnitude/spectral type for the acquisition of spectra of planetary atmospheres for a variety of scenarios: hot, warm, and temperate planets orbiting stars ranging in spectral type from hot F- to cooler M-dwarfs. Our results include key examples of known planets (e.g., HD 189733b, GJ 436b, GJ 1214b, and Cancri 55 e) and simulations of plausible terrestrial and gaseous planets, with a variety of thermodynamical conditions. We conclude that even most challenging targets, such as super-Earths in the habitable zone of late-type stars, are within reach of an M-class, space-based spectroscopy mission.

[1]  Stephen R. Kane,et al.  CHARACTERIZING THE VARIABILITY OF STARS WITH EARLY-RELEASE KEPLER DATA , 2010, 1009.1840.

[2]  O. Grasset,et al.  A STUDY OF THE ACCURACY OF MASS–RADIUS RELATIONSHIPS FOR SILICATE-RICH AND ICE-RICH PLANETS UP TO 100 EARTH MASSES , 2009, 0902.1640.

[3]  Drake Deming,et al.  Possible thermochemical disequilibrium in the atmosphere of the exoplanet GJ 436b , 2010, Nature.

[4]  W. D. Cochran,et al.  Kepler’s Optical Phase Curve of the Exoplanet HAT-P-7b , 2009, Science.

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

[6]  J. Beaulieu,et al.  METHANE IN THE ATMOSPHERE OF THE TRANSITING HOT NEPTUNE GJ436B? , 2010, 1007.0324.

[7]  Simon Albrecht,et al.  The orbital motion, absolute mass and high-altitude winds of exoplanet HD 209458b , 2010, Nature.

[8]  David Charbonneau,et al.  Hubble Space Telescope Time-Series Photometry of the Transiting Planet of HD?209458 , 2001 .

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

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

[11]  R. Akeson,et al.  The Mid-Infrared Spectrum of the Transiting Exoplanet HD 209458b , 2007, astro-ph/0702593.

[12]  Eric Gaidos,et al.  AN ALL-SKY CATALOG OF BRIGHT M DWARFS , 2011, 1108.2719.

[13]  Robert L. Kurucz,et al.  The Solar Spectrum: Atlases and Line Identifications , 1995 .

[14]  D. Queloz,et al.  Detection of transits of the nearby hot Neptune GJ 436 b , 2007, Astronomy & Astrophysics.

[15]  Debra A. Fischer,et al.  A Neptune-Mass Planet Orbiting the Nearby M Dwarf GJ 436 , 2004 .

[16]  I. Ribas,et al.  Primary Transit of the Planet HD 189733b at 3.6 and 5.8 μm , 2007, 0711.2142.

[17]  David Charbonneau,et al.  A map of the day–night contrast of the extrasolar planet HD 189733b , 2007, Nature.

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

[19]  Antonino Francesco Lanza,et al.  Multiwavelength flux variations induced by stellar magnetic activity: effects on planetary transits , 2012, 1201.3514.

[20]  I. P. Waldmann,et al.  GROUND-BASED NEAR-INFRARED EMISSION SPECTROSCOPY OF HD 189733B , 2011, 1104.0570.

[21]  D. Ehrenreich,et al.  Infrared Transmission Spectra for Extrasolar Giant Planets , 2006, astro-ph/0611174.

[22]  David Charbonneau,et al.  THE 8 μm PHASE VARIATION OF THE HOT SATURN HD 149026b , 2009, 0908.1977.

[23]  Martin G. Cohen,et al.  THE WIDE-FIELD INFRARED SURVEY EXPLORER (WISE): MISSION DESCRIPTION AND INITIAL ON-ORBIT PERFORMANCE , 2010, 1008.0031.

[24]  P. McCullough,et al.  PROBING THE TERMINATOR REGION ATMOSPHERE OF THE HOT-JUPITER XO-1b WITH TRANSMISSION SPECTROSCOPY , 2010, 1002.2434.

[25]  A. Sozzetti.  The Gaia astrometric survey , 2009, Proceedings of the International Astronomical Union.

[26]  Michael Perryman,et al.  Astronomical Applications of Astrometry: The Hipparcos and Tycho Catalogues , 2008 .

[27]  S. Seager,et al.  A Unique Solution of Planet and Star Parameters from an Extrasolar Planet Transit Light Curve , 2002, astro-ph/0206228.

[28]  J. Beuzit,et al.  Accurate masses of very low mass stars: IV Improved mass-luminosity relations , 2000, astro-ph/0010586.

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

[30]  G. Tinetti,et al.  Disk-averaged synthetic spectra of Mars. , 2004, Astrobiology.

[31]  Nicolas B. Cowan,et al.  A MODEL FOR THERMAL PHASE VARIATIONS OF CIRCULAR AND ECCENTRIC EXOPLANETS , 2010, 1011.0428.

[32]  Jaymie M. Matthews,et al.  A SUPER-EARTH TRANSITING A NAKED-EYE STAR , 2011, 1104.5230.

[33]  J. Beaulieu,et al.  Exploring extrasolar worlds: from gas giants to terrestrial habitable planets. , 2010, Faraday discussions.

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

[35]  L. Walkowicz,et al.  PHOTOMETRIC VARIABILITY IN KEPLER TARGET STARS: THE SUN AMONG STARS—A FIRST LOOK , 2010, 1001.0414.

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

[37]  Darren M. Williams,et al.  Seasonality on terrestrial extrasolar planets: inferring obliquity and surface conditions from infrared light curves , 2004 .

[38]  D. Charbonneau,et al.  THE CLIMATE OF HD 189733b FROM FOURTEEN TRANSITS AND ECLIPSES MEASURED BY SPITZER , 2010, 1007.4378.

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

[40]  Jonathan Tennyson,et al.  Water in the atmosphere of HD 209458b from 3.6–8 μm IRAC photometric observations in primary transit , 2010 .

[41]  G. Laughlin,et al.  Hydrodynamic Simulations of Unevenly Irradiated Jovian Planets , 2007, 0711.2106.

[42]  David Charbonneau,et al.  Using Stellar Limb-Darkening to Refine the Properties of HD 209458b , 2006, astro-ph/0603542.

[43]  J. Tennyson,et al.  A high-accuracy computed water line list , 2006, astro-ph/0601236.

[44]  J. Fortney,et al.  Resolving the Surfaces of Extrasolar Planets with Secondary Eclipse Light Curves , 2006, astro-ph/0601092.

[45]  S. Seager,et al.  A NEW 24 μm PHASE CURVE FOR υ ANDROMEDAE b , 2010, 1008.0393.

[46]  D. Charbonneau,et al.  Hot nights on extrasolar planets: mid‐infrared phase variations of hot Jupiters , 2007, 0705.1189.

[47]  Peter Hauschildt,et al.  Evolutionary models for solar metallicity low - mass stars: Mass - magnitude relationships and color - magnitude diagrams , 1998 .

[48]  Drake Deming,et al.  A SPITZER TRANSMISSION SPECTRUM FOR THE EXOPLANET GJ 436b, EVIDENCE FOR STELLAR VARIABILITY, AND CONSTRAINTS ON DAYSIDE FLUX VARIATIONS , 2011, 1104.2901.

[49]  R. Rosenfeld.  Nature , 2009, Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery.

[50]  N. Iro,et al.  A TIME-DEPENDENT RADIATIVE MODEL FOR THE ATMOSPHERE OF THE ECCENTRIC EXOPLANETS , 2010, 1001.1171.

[51]  S. Seager,et al.  Toward Eclipse Mapping of Hot Jupiters , 2006, astro-ph/0612412.

[52]  M. Marley,et al.  ATMOSPHERIC CIRCULATION OF ECCENTRIC HOT NEPTUNE GJ436b , 2010, 1007.2942.

[53]  Jonathan Tennyson,et al.  HITEMP, the high-temperature molecular spectroscopic database , 2010 .

[54]  Margaret Turnbull,et al.  Detectability of planetary characteristics in disk-averaged spectra. I: The Earth model. , 2006, Astrobiology.

[55]  L. Walkowicz,et al.  PHOTOMETRIC VARIABILITY IN KEPLER TARGET STARS. II. AN OVERVIEW OF AMPLITUDE, PERIODICITY, AND ROTATION IN FIRST QUARTER DATA , 2010, 1008.1092.

[56]  Természettudományok.  Extrasolar Planets Encyclopaedia , 2010 .

[57]  S. Tashkun,et al.  CDSD-4000: High-resolution, high-temperature carbon dioxide spectroscopic databank , 2011 .

[58]  M. A. C. Perryman,et al.  The Hipparcos and Tycho catalogues : astrometric and photometric star catalogues derived from the ESA Hipparcos Space Astrometry Mission , 1997 .

[59]  Drake Deming,et al.  The Phase-Dependent Infrared Brightness of the Extrasolar Planet ʊ Andromedae b , 2006, Science.

[60]  David Charbonneau,et al.  MULTIWAVELENGTH CONSTRAINTS ON THE DAY–NIGHT CIRCULATION PATTERNS OF HD 189733b , 2008, 0802.1705.

[61]  J. Tennyson,et al.  Water in exoplanets , 2012, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[62]  Jonathan Tennyson,et al.  Water vapour in the atmosphere of a transiting extrasolar planet , 2007, Nature.

[63]  J. Tennyson,et al.  A variationally computed line list for hot NH3 , 2010, 1011.1569.

[64]  Carl J. Grillmair,et al.  Strong water absorption in the dayside emission spectrum of the planet HD 189733b , 2008, Nature.

[65]  Matthew Joseph Griffin,et al.  Exoplanet characterisation observatory , 2012 .

[66]  M. G. Lattanzi,et al.  Double-blind test program for astrometric planet detection with Gaia , 2008, 0802.0515.

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

[68]  Michel Mayor,et al.  ELODIE metallicity-biased search for transiting Hot Jupiters. II. A very hot Jupiter transiting the bright K star HD 189733 , 2005 .

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

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

[71]  S. Albrecht,et al.  The changing phases of extrasolar planet CoRoT-1b , 2009, Nature.

[72]  Nicolas B. Cowan,et al.  Inverting Phase Functions to Map Exoplanets , 2008, 0803.3622.

[73]  Franck Selsis,et al.  Thermal phase curves of nontransiting terrestrial exoplanets - I. Characterizing atmospheres , 2011, 1104.4763.