The discovery of WASP-151b, WASP-153b, WASP-156b: Insights on giant planet migration and the upper boundary of the Neptunian desert

To investigate the origin of the features discovered in the exoplanet population, the knowledge of exoplanets' mass and radius with a good precision is essential. In this paper, we report the discovery of three transiting exoplanets by the SuperWASP survey and the SOPHIE spectrograph with mass and radius determined with a precision better than 15 %. WASP-151b and WASP-153b are two hot Saturns with masses, radii, densities and equilibrium temperatures of 0.31^{+0.04}_{-0.03} MJ, 1.13^{+0.03}_{-0.03} RJ, 0.22^{-0.03}_{-0.02} rhoJ and 1, 290^{+20}_{-10} K, and 0.39^{+0.02}_{-0.02} MJ, 1.55^{+0.10}_{-0.08} RJ, 0.11^{+0.02}_{-0.02} rhoJ and 1, 700^{+40}_{-40} K, respectively. Their host stars are early G type stars (with magV ~ 13) and their orbital periods are 4.53 and 3.33 days, respectively. WASP-156b is a Super-Neptune orbiting a K type star (magV = 11.6) . It has a mass of 0.128^{+0.010}_{-0.009} MJ, a radius of 0.51^{+0.02}_{-0.02} RJ, a density of 1.0^{+0.1}_{-0.1} rhoJ, an equilibrium temperature of 970^{+30}_{-20} K and an orbital period of 3.83 days. WASP-151b is slightly inflated, while WASP-153b presents a significant radius anomaly. WASP-156b, being one of the few well characterised Super-Neptunes, will help to constrain the formation of Neptune size planets and the transition between gas and ice giants. The estimates of the age of these three stars confirms the tendency for some stars to have gyrochronological ages significantly lower than their isochronal ages. We propose that high eccentricity migration could partially explain this behaviour for stars hosting a short period planet. Finally, these three planets also lie close to (WASP-151b and WASP-153b) or below (WASP-156b) the upper boundary of the Neptunian desert. Their characteristics support that the ultra-violet irradiation plays an important role in this depletion of planets observed in the exoplanet population.

[1]  S. C. C. Barros,et al.  New planetary and eclipsing binary candidates from campaigns 1−6 of the K2 mission , 2016, 1607.02339.

[2]  E. Ford,et al.  Evidence for Two Hot-Jupiter Formation Paths , 2017, 1703.09711.

[3]  R. G. West,et al.  WASP-42 b and WASP-49 b: two new transiting sub-Jupiters , 2012, 1205.2757.

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

[5]  R. G. West,et al.  From Dense Hot Jupiter to Low Density Neptune: The Discovery of WASP-127b, WASP-136b and WASP-138b , 2016, 1607.07859.

[6]  A. D. Etangs,et al.  A diagram to determine the evaporation status of extrasolar planets , 2006, astro-ph/0609744.

[7]  Suzanne Aigrain,et al.  ldtk: Limb Darkening Toolkit , 2015, 1508.02634.

[8]  Jonathan J. Fortney,et al.  THE HEAVY-ELEMENT MASSES OF EXTRASOLAR GIANT PLANETS, REVEALED , 2011, 1105.0024.

[9]  Eric B. Ford,et al.  Dynamical Instabilities and the Formation of Extrasolar Planetary Systems , 1996, Science.

[10]  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.

[11]  Daniel Foreman-Mackey,et al.  emcee: The MCMC Hammer , 2012, 1202.3665.

[12]  W. Farr,et al.  ON THE FORMATION OF HOT JUPITERS IN STELLAR BINARIES , 2012, 1206.3529.

[13]  D. Queloz,et al.  The CORALIE survey for southern extra-solar planets VII - Two short-period Saturnian companions to HD 108147 and HD 168746 , 2002, astro-ph/0202457.

[14]  Spain.,et al.  Bayesian mass and age estimates for transiting exoplanet host stars , 2014, 1412.7891.

[15]  D. F. Gray,et al.  The Observation and Analysis of Stellar Photospheres , 2021 .

[16]  T. Matsakos,et al.  ON THE ORIGIN OF THE SUB-JOVIAN DESERT IN THE ORBITAL-PERIOD–PLANETARY-MASS PLANE , 2016, 1603.00414.

[17]  A. Weiss,et al.  GARSTEC—the Garching Stellar Evolution Code , 2008 .

[18]  J. Winn,et al.  THE OCCURRENCE OF ADDITIONAL GIANT PLANETS INSIDE THE WATER–ICE LINE IN SYSTEMS WITH HOT JUPITERS: EVIDENCE AGAINST HIGH-ECCENTRICITY MIGRATION , 2016, 1604.03107.

[19]  R. G. West,et al.  WASP-39b: a highly inflated Saturn-mass planet orbiting a late G-type star , 2011, 1102.1375.

[20]  C. S. Fernandes,et al.  A seven-planet resonant chain in TRAPPIST-1 , 2017, Nature Astronomy.

[21]  Ansgar Reiners,et al.  A new extensive library of PHOENIX stellar atmospheres and synthetic spectra , 2013, 1303.5632.

[22]  R. Street,et al.  WASP-41b: A Transiting Hot Jupiter Planet Orbiting a Magnetically Active G8V Star , 2010, 1012.2977.

[23]  G. Kov'acs,et al.  A box-fitting algorithm in the search for periodic transits , 2002, astro-ph/0206099.

[24]  P. Bodenheimer,et al.  Orbital migration of the planetary companion of 51 Pegasi to its present location , 1996, Nature.

[25]  Spain.,et al.  A comparison of gyrochronological and isochronal age estimates for transiting exoplanet host stars , 2015, 1503.09111.

[26]  Sofia Randich,et al.  Time scales of Li evolution: A Homogeneous analysis of open clusters from ZAMS to late-MS , 2005 .

[27]  Pierre Le Sidaner,et al.  Defining and cataloging exoplanets: the exoplanet.eu database , 2011, 1106.0586.

[28]  Cambridge,et al.  A Detailed Model Grid for Solid Planets from 0.1 through 100 Earth Masses , 2013, 1301.0818.

[29]  L. Kiss,et al.  A SHORT-PERIOD CENSOR OF SUB-JUPITER MASS EXOPLANETS WITH LOW DENSITY , 2010, 1012.4791.

[30]  R. W. Noyes,et al.  A trend filtering algorithm for wide-field variability surveys , 2004 .

[31]  C. Moutou,et al.  The SOPHIE search for northern extrasolar planets. III. A Jupiter-mass companion around HD 109246 , 2010, 1006.4984.

[32]  Jie Li,et al.  Transiting circumbinary planets Kepler-34 b and Kepler-35 b , 2012, Nature.

[33]  W. Chaplin,et al.  Determining stellar macroturbulence using asteroseismic rotational velocities from Kepler , 2014, 1408.3988.

[34]  Tokyo Institute of Technology,et al.  MASS-LOSS EVOLUTION OF CLOSE-IN EXOPLANETS: EVAPORATION OF HOT JUPITERS AND THE EFFECT ON POPULATION , 2014, 1401.2511.

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

[36]  B. Enoch,et al.  The WASP Project and the SuperWASP Cameras , 2006, astro-ph/0608454.

[37]  R. G. West,et al.  WASP-38b: a transiting exoplanet in an eccentric, 6.87d period orbit , 2010, 1010.0849.

[38]  Hema Chandrasekaran,et al.  Pixel-level calibration in the Kepler Science Operations Center pipeline , 2010, Astronomical Telescopes + Instrumentation.

[39]  S. Udry,et al.  WASP-South transiting exoplanets: WASP-130b, WASP-131b, WASP-132b, WASP-139b, WASP-140b, WASP-141b & WASP-142b , 2016, 1604.04195.

[40]  Thierry Forveille,et al.  The SOPHIE search for northern extrasolar planets . I. A companion around HD 16760 with mass close to the planet/brown-dwarf transition , 2009 .

[41]  Tsevi Mazeh,et al.  Dearth of short-period Neptunian exoplanets - a desert in period-mass and period-radius planes , 2016, 1602.07843.

[42]  R. G. West,et al.  Efficient identification of exoplanetary transit candidates from SuperWASP light curves , 2007, 0707.0417.

[43]  Miguel de Val-Borro,et al.  HATS-7b: A HOT SUPER NEPTUNE TRANSITING A QUIET K DWARF STAR , 2015, 1507.01024.

[44]  Howard Isaacson,et al.  MODELING KEPLER TRANSIT LIGHT CURVES AS FALSE POSITIVES: REJECTION OF BLEND SCENARIOS FOR KEPLER-9, AND VALIDATION OF KEPLER-9 d, A SUPER-EARTH-SIZE PLANET IN A MULTIPLE SYSTEM , 2010, 1008.4393.

[45]  Prasanth H. Nair,et al.  Astropy: A community Python package for astronomy , 2013, 1307.6212.

[46]  University of Warwick,et al.  DONUTS: A Science Frame Autoguiding Algorithm with Sub-Pixel Precision, Capable of Guiding on Defocused Stars , 2013, 1304.2405.

[47]  F. Mullally,et al.  The K2 Mission: Characterization and Early Results , 2014, 1402.5163.

[48]  James R. Graham,et al.  Exploring the formation and evolution of planetary systems : proceedings of the 299th symposium of the International Astronomical Union, held in Victoria, Canada, June 2-7, 2013 , 2013 .

[49]  M. Asplund,et al.  The chemical composition of the Sun , 2009, 0909.0948.

[50]  John C. Geary,et al.  ARCHITECTURE OF KEPLER'S MULTI-TRANSITING SYSTEMS. II. NEW INVESTIGATIONS WITH TWICE AS MANY CANDIDATES , 2012, The Astrophysical Journal.

[51]  A. Gimenez,et al.  Accurate masses and radii of normal stars: modern results and applications , 2009, 0908.2624.

[52]  S. Baliunas,et al.  No Planet for Hd 166435 , 2022 .

[53]  P. Giommi,et al.  The PLATO 2.0 mission , 2013, 1310.0696.

[54]  R. Dawson,et al.  GIANT PLANETS ORBITING METAL-RICH STARS SHOW SIGNATURES OF PLANET–PLANET INTERACTIONS , 2013, 1302.6244.

[55]  Eike W. Guenther,et al.  HD15082b, a short-period planet orbiting an A-star , 2011 .

[56]  A. Collier Cameron,et al.  A fast hybrid algorithm for exoplanetary transit searches , 2006, astro-ph/0609418.

[57]  A. Cameron,et al.  Accurate spectroscopic parameters of WASP planet host stars , 2012, 1210.5931.

[58]  Howard Isaacson,et al.  Kepler Planet-Detection Mission: Introduction and First Results , 2010, Science.

[59]  R. G. West,et al.  The discoveries of WASP-91b, WASP-105b and WASP-107b: two warm Jupiters and a planet in the transition region between ice giants and gas giants , 2017, 1701.03776.

[60]  R. Angus,et al.  Calibrating gyrochronology using Kepler asteroseismic targets , 2015, 1502.06965.

[61]  Tsevi Mazeh,et al.  Correcting systematic effects in a large set of photometric light curves , 2005, astro-ph/0502056.

[62]  L. Close,et al.  DISCOVERY AND VALIDATION OF A HIGH-DENSITY SUB-NEPTUNE FROM THE K2 MISSION , 2016, 1601.07608.

[63]  Paolo Conconi,et al.  Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series , 2012 .

[64]  J. Fortney,et al.  RE-INFLATED WARM JUPITERS AROUND RED GIANTS , 2015, 1510.00067.

[65]  P. Gregory.  Bayesian Logical Data Analysis for the Physical Sciences: The how-to of Bayesian inference , 2005 .

[66]  R. G. West,et al.  WASP-3b: a strongly irradiated transiting gas-giant planet , 2007, 0711.0126.

[67]  M. Payne,et al.  Formation and Evolution of Planetary Systems , 2010 .

[68]  S. Barnes.  Accepted for publication in The Astrophysical Journal Ages for illustrative field stars using gyrochronology: viability, limitations and errors , 2022 .

[69]  France,et al.  PASTIS: Bayesian extrasolar planet validation. I. General framework, models, and performance , 2014, 1403.6725.

[70]  S. Hinkley,et al.  A Neptune-sized transiting planet closely orbiting a 5–10-million-year-old star , 2016, Nature.

[71]  S. Tremaine,et al.  Submitted to ApJ Preprint typeset using L ATEX style emulateapj v. 10/09/06 SHRINKING BINARY AND PLANETARY ORBITS BY KOZAI CYCLES WITH TIDAL FRICTION , 2022 .

[72]  E. Agol,et al.  EVEREST: PIXEL LEVEL DECORRELATION OF K2 LIGHT CURVES , 2016, 1607.00524.

[73]  Hot moons and cool stars , 2013, 1301.0235.

[74]  Christian Schwab,et al.  AN AFFINE-INVARIANT SAMPLER FOR EXOPLANET FITTING AND DISCOVERY IN RADIAL VELOCITY DATA , 2011, 1104.2612.

[75]  R. G. West,et al.  Line-profile tomography of exoplanet transits - II. A gas-giant planet transiting a rapidly rotating A5 star , 2010, 1004.4551.

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

[77]  European Southern Observatory,et al.  The CORALIE survey for southern extra-solar planets - IX. A 1.3-day period brown dwarf disguised as a planet , 2002 .

[78]  Jean Manfroid,et al.  TRAPPIST: TRAnsiting Planets and PlanetesImals Small Telescope , 2011 .

[79]  Coventry,et al.  A search for photometric variability towards M71 with the Near-Infrared Transiting ExoplanetS Telescope , 2013, 1312.5880.

[80]  I. Baraffe,et al.  Structure and evolution of super-Earth to super-Jupiter exoplanets - I. Heavy element enrichment in the interior , 2008, 0802.1810.

[81]  M. Skrutskie,et al.  The Two Micron All Sky Survey (2MASS) , 2006 .

[82]  P. Figueira,et al.  A Pragmatic Bayesian Perspective on Correlation Analysis , 2016, Origins of Life and Evolution of Biospheres.

[83]  P. Stetson.  DAOPHOT: A COMPUTER PROGRAM FOR CROWDED-FIELD STELLAR PHOTOMETRY , 1987 .

[84]  D. Buzasi,et al.  Rotation, activity, and stellar obliquities in a large uniform sample of Kepler solar analogs , 2016 .

[85]  A. Santerne,et al.  PASTIS: Bayesian extrasolar planet validation II. Constraining exoplanet blend scenarios using spectroscopic diagnoses , 2015, 1505.02663.

[86]  D. Bossini,et al.  THE ASTEROSEISMIC POTENTIAL OF TESS: EXOPLANET-HOST STARS , 2016, 1608.01138.

[87]  M. Mayor,et al.  From 51 Peg to Earth-type planets , 2012 .

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

[89]  Miguel de Val-Borro,et al.  HATS-8b: A LOW-DENSITY TRANSITING SUPER-NEPTUNE , 2015, 1506.01334.