An Accurate Mass Determination for Kepler-1655b, a Moderately Irradiated World with a Significant Volatile Envelope

We present the confirmation of a small, moderately irradiated (F = 155 ± 7 F⊕) Neptune with a substantial gas envelope in a P = 11.8728787 ± 0.0000085 day orbit about a quiet, Sun-like G0V star Kepler-1655. Based on our analysis of the Kepler light curve, we determined Kepler-1655b’s radius to be 2.213 ± 0.082 R⊕. We acquired 95 high-resolution spectra with Telescopio Nazionale Galileo/HARPS-N, enabling us to characterize the host star and determine an accurate mass for Kepler-1655b of via Gaussian-process regression. Our mass determination excludes an Earth-like composition with 98% confidence. Kepler-1655b falls on the upper edge of the evaporation valley, in the relatively sparsely occupied transition region between rocky and gas-rich planets. It is therefore part of a population of planets that we should actively seek to characterize further.

[1]  A. Cameron,et al.  A Kepler study of starspot lifetimes with respect to light-curve amplitude and spectral type , 2017, 1707.08583.

[2]  R. P. Butler,et al.  Three’s Company: An Additional Non-transiting Super-Earth in the Bright HD 3167 System, and Masses for All Three Planets , 2017, 1706.01892.

[3]  Christoph Mordasini,et al.  Compositional Imprints in Density–Distance–Time: A Rocky Composition for Close-in Low-mass Exoplanets from the Location of the Valley of Evaporation , 2017, 1706.00251.

[4]  James E. Owen,et al.  The Evaporation Valley in the Kepler Planets , 2017, 1705.10810.

[5]  S. Udry,et al.  Atmospheric Stellar Parameters from Cross-Correlation Functions , 2017, 1705.02343.

[6]  Howard Isaacson,et al.  The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets , 2017, 1703.10375.

[7]  F. Bouchy,et al.  The Kepler-19 System: A Thick-envelope Super-Earth with Two Neptune-mass Companions Characterized Using Radial Velocities and Transit Timing Variations , 2017, 1703.06885.

[8]  A. Collier Cameron,et al.  Stacked Bayesian general Lomb-Scargle periodogram : identifying stellar activity signals , 2017, 1702.03885.

[9]  L. Fossati,et al.  The effect of ISM absorption on stellar activity measurements and its relevance for exoplanet studies , 2017, 1702.02883.

[10]  Khadeejah A. Zamudio,et al.  Kepler: A Search for Terrestrial Planets - Kepler Data Characterization Handbook , 2016 .

[11]  K. Rice,et al.  How formation time-scales affect the period dependence of the transition between rocky super-Earths and gaseous sub-Neptunesand implications for η⊕ , 2016, Monthly Notices of the Royal Astronomical Society.

[12]  E. Lopez.  Born dry in the photoevaporation desert: Kepler's ultra-short-period planets formed water-poor , 2016, 1610.01170.

[13]  A. Bonomo,et al.  KEPLER-21b: A ROCKY PLANET AROUND A V = 8.25 mag STAR , 2016, 1609.07617.

[14]  A. Bonomo,et al.  A 1.9 EARTH RADIUS ROCKY PLANET AND THE DISCOVERY OF A NON-TRANSITING PLANET IN THE KEPLER-20 SYSTEM , 2016, 1608.06836.

[15]  M. R. Haas,et al.  FALSE POSITIVE PROBABILITIES FOR ALL KEPLER OBJECTS OF INTEREST: 1284 NEWLY VALIDATED PLANETS AND 428 LIKELY FALSE POSITIVES , 2016, 1605.02825.

[16]  R. Gilliland,et al.  Hot super-Earths stripped by their host stars , 2016, Nature Communications.

[17]  A. Collier Cameron,et al.  The Sun as a planet-host star: proxies from SDO images for HARPS radial-velocity variations , 2016, 1601.05651.

[18]  Dimitar Sasselov,et al.  MASS–RADIUS RELATION FOR ROCKY PLANETS BASED ON PREM , 2015, 1512.08827.

[19]  Katherine M. Deck,et al.  SECURE MASS MEASUREMENTS FROM TRANSIT TIMING: 10 KEPLER EXOPLANETS BETWEEN 3 AND 8 M ⊕ WITH DIVERSE DENSITIES AND INCIDENT FLUXES , 2015, 1512.02003.

[20]  A. Bonomo,et al.  THE KEPLER-454 SYSTEM: A SMALL, NOT-ROCKY INNER PLANET, A JOVIAN WORLD, AND A DISTANT COMPANION , 2015, 1511.09097.

[21]  Nicolas Buchschacher,et al.  HARPS-N OBSERVES THE SUN AS A STAR , 2015, 1511.02267.

[22]  Stephen J. Roberts,et al.  Ghost in the time series: no planet for Alpha Cen B , 2015, 1510.05598.

[23]  Steven Reece,et al.  A Gaussian process framework for modelling stellar activity signals in radial velocity data , 2015, 1506.07304.

[24]  S. D. Kawaler,et al.  Ages and fundamental properties of Kepler exoplanet host stars from asteroseismology , 2015, 1504.07992.

[25]  Eric B. Ford,et al.  PROBABILISTIC MASS–RADIUS RELATIONSHIP FOR SUB-NEPTUNE-SIZED PLANETS , 2015, 1504.07557.

[26]  Antonino Francesco Lanza,et al.  Testing the recovery of stellar rotation signals from Kepler light curves using a blind hare-and-hounds exercise , 2015, 1504.04029.

[27]  S. G. Sousa,et al.  ARES v2 - new features and improved performance , 2015, 1504.02725.

[28]  Timothy D. Morton,et al.  VESPA: False positive probabilities calculator , 2015 .

[29]  C. Baranec,et al.  AN ANCIENT EXTRASOLAR SYSTEM WITH FIVE SUB-EARTH-SIZE PLANETS , 2015, 1501.06227.

[30]  D. Charbonneau,et al.  THE OCCURRENCE OF POTENTIALLY HABITABLE PLANETS ORBITING M DWARFS ESTIMATED FROM THE FULL KEPLER DATASET AND AN EMPIRICAL MEASUREMENT OF THE DETECTION SENSITIVITY , 2015, 1501.01623.

[31]  R. Haywood,et al.  DETERMINING THE MASS OF KEPLER-78b WITH NONPARAMETRIC GAUSSIAN PROCESS ESTIMATION , 2015, 1501.00369.

[32]  A. Santerne,et al.  BGLS: A Bayesian formalism for the generalised Lomb-Scargle periodogram , 2014, 1412.0467.

[33]  V. Adibekyan,et al.  Correcting the spectroscopic surface gravity using transits and asteroseismology - No significant effect on temperatures or metallicities with ARES and MOOG in local thermodynamic equilibrium , 2014, 1410.1310.

[34]  Nuno C. Santos,et al.  SOAP 2.0: A TOOL TO ESTIMATE THE PHOTOMETRIC AND RADIAL VELOCITY VARIATIONS INDUCED BY STELLAR SPOTS AND PLAGES , 2014, 1409.3594.

[35]  S. Sousa.  ARES + MOOG: A Practical Overview of an Equivalent Width (EW) Method to Derive Stellar Parameters , 2014, 1407.5817.

[36]  L. Rogers.  MOST 1.6 EARTH-RADIUS PLANETS ARE NOT ROCKY , 2014, 1407.4457.

[37]  Michael C. Kotson,et al.  A STUDY OF THE SHORTEST-PERIOD PLANETS FOUND WITH KEPLER , 2014, 1403.2379.

[38]  E. Agol,et al.  VALIDATION OF KEPLER'S MULTIPLE PLANET CANDIDATES. III. LIGHT CURVE ANALYSIS AND ANNOUNCEMENT OF HUNDREDS OF NEW MULTI-PLANET SYSTEMS , 2014, 1402.6534.

[39]  T. Mazeh,et al.  ROTATION PERIODS OF 34,030 KEPLER MAIN-SEQUENCE STARS: THE FULL AUTOCORRELATION SAMPLE , 2014, 1402.5694.

[40]  G. Marcy,et al.  THE MASS–RADIUS RELATION FOR 65 EXOPLANETS SMALLER THAN 4 EARTH RADII , 2013, 1312.0936.

[41]  H. Müller,et al.  High-precision stellar limb-darkening measurements - A transit study of 38 Kepler planetary candidates , 2013 .

[42]  J. Fortney,et al.  UNDERSTANDING THE MASS–RADIUS RELATION FOR SUB-NEPTUNES: RADIUS AS A PROXY FOR COMPOSITION , 2013, 1311.0329.

[43]  S. Hadden,et al.  DENSITIES AND ECCENTRICITIES OF 139 KEPLER PLANETS FROM TRANSIT TIME VARIATIONS , 2013, 1310.7942.

[44]  A. Collier Cameron,et al.  Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system , 2013, Proceedings of the International Astronomical Union.

[45]  Paul M. Brunet,et al.  The Gaia mission , 2013, 1303.0303.

[46]  F. Mullally,et al.  FUNDAMENTAL PROPERTIES OF KEPLER PLANET-CANDIDATE HOST STARS USING ASTEROSEISMOLOGY , 2013, 1302.2624.

[47]  Nicolas Buchschacher,et al.  Harps-N: the new planet hunter at TNG , 2012, Other Conferences.

[48]  B. Scott Gaudi,et al.  EXOFAST: A Fast Exoplanetary Fitting Suite in IDL , 2012, 1206.5798.

[49]  I. Boisse,et al.  SOAP. A tool for the fast computation of photometry and radial velocity induced by stellar spots , 2012, 1206.5493.

[50]  T. Morton.  AN EFFICIENT AUTOMATED VALIDATION PROCEDURE FOR EXOPLANET TRANSIT CANDIDATES , 2012, 1206.1568.

[51]  R. Dawson,et al.  THE PHOTOECCENTRIC EFFECT AND PROTO-HOT JUPITERS. I. MEASURING PHOTOMETRIC ECCENTRICITIES OF INDIVIDUAL TRANSITING PLANETS , 2012, 1203.5537.

[52]  Martin C. Stumpe,et al.  Kepler Presearch Data Conditioning II - A Bayesian Approach to Systematic Error Correction , 2012, 1203.1383.

[53]  Jeffery J. Kolodziejczak,et al.  Kepler Presearch Data Conditioning I—Architecture and Algorithms for Error Correction in Kepler Light Curves , 2012, 1203.1382.

[54]  S. Lucatello,et al.  MOOG: LTE line analysis and spectrum synthesis , 2012 .

[55]  J. Coughlin,et al.  A UNIFORM SEARCH FOR SECONDARY ECLIPSES OF HOT JUPITERS IN KEPLER Q2 LIGHT CURVES , 2011, 1112.1021.

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

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

[58]  Instituto de Astrof'isica de Canarias,et al.  Spectroscopic characterization of a sample of metal-poor solar-type stars from the HARPS planet search program , 2010, 1012.1528.

[59]  Howard Isaacson,et al.  CHROMOSPHERIC ACTIVITY AND JITTER MEASUREMENTS FOR 2630 STARS ON THE CALIFORNIA PLANET SEARCH , 2010, 1009.2301.

[60]  Anne-Marie Lagrange,et al.  Reconstructing the solar integrated radial velocity using MDI/SOHO , 2010, 1005.4764.

[61]  Daniel C. Fabrycky,et al.  RADIAL VELOCITY PLANETS DE-ALIASED: A NEW, SHORT PERIOD FOR SUPER-EARTH 55 Cnc e , 2010, 1005.4050.

[62]  Jonathan R Goodman,et al.  Ensemble samplers with affine invariance , 2010 .

[63]  A. Lagrange,et al.  Using the Sun to estimate Earth-like planets detection capabilities - I. Impact of cold spots , 2010, 1001.1449.

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

[65]  C. Keller,et al.  An analytical model to demonstrate the reliability of reconstructed ‘active longitudes’. , 2009 .

[66]  S. Redfield,et al.  The Structure of the Local Interstellar Medium. V. Electron Densities , 2008, 0804.1802.

[67]  Jeffrey L. Linsky,et al.  The Structure of the Local Interstellar Medium. IV. Dynamics, Morphology, Physical Properties, and Implications of Cloud-Cloud Interactions , 2007, 0709.4480.

[68]  A. Weiss,et al.  Basic physical parameters of a selected sample of evolved stars , 2006, astro-ph/0608160.

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

[70]  F. Bouchy,et al.  From CORALIE to HARPS. The way towards 1 m s-1 precision Doppler measurements , 2001 .

[71]  J. Mathis,et al.  Dependence of Gas-Phase Abundances in the Interstellar Medium on Column Density , 2000, astro-ph/0010045.

[72]  Robert A. Donahue,et al.  Activity-Related Radial Velocity Variation in Cool Stars , 1997 .

[73]  L. van Driel-Gesztelyi,et al.  Making Sense of Sunspot Decay. I. Parabolic Decay Law and Gnevyshev–Waldmeier Relation , 1997, astro-ph/9706029.

[74]  Michel Mayor,et al.  ELODIE: A spectrograph for accurate radial velocity measurements , 1996 .

[75]  Blair D. Savage,et al.  An IUE Survey of Interstellar H I LY alpha Absorption , 1994 .

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

[77]  R Edelson,et al.  The Discrete Correlation Function: a New Method for Analyzing Unevenly Sampled Variability Data , 1988 .

[78]  Jie Li,et al.  Kepler Data Processing Handbook: Data Validation II. Transit Model Fitting and Multiple Planet Search , 2017 .

[79]  B. Smalley,et al.  Determination of Atmospheric Parameters of B-, A-, F- and G-Type Stars: Lectures from the School of Spectroscopic Data Analyses , 2014 .

[80]  Martin C. Stumpe,et al.  Multiscale Systematic Error Correction via Wavelet-Based Bandsplitting in Kepler Data , 2014 .

[81]  P. Foukal.  Solar Astrophysics, 2nd, Revised Edition , 2004 .

[82]  R. Kurucz.  ATLAS9 Stellar Atmosphere Programs and 2 km/s grid. , 1993 .