FIVE PLANETS TRANSITING A NINTH MAGNITUDE STAR

The Kepler mission has revealed a great diversity of planetary systems and architectures, but most of the planets discovered by Kepler orbit faint stars. Using new data from the K2 mission, we present the discovery of a five planet system transiting a bright (V = 8.9, K = 7.7) star called HIP 41378. HIP 41378 is a slightly metal-poor late F-type star with moderate rotation (v sin(i) = 7 km/s) and lies at a distance of 116 +/- 18 from Earth. We find that HIP 41378 hosts two sub-Neptune sized planets orbiting 3.5% outside a 2:1 period commensurability in 15.6 and 31.7 day orbits. In addition, we detect three planets which each transit once during the 75 days spanned by K2 observations. One planet is Neptune sized in a likely ~160 day orbit, one is sub-Saturn sized likely in a ~130 day orbit, and one is a Jupiter sized planet in a likely ~1 year orbit. We show that these estimates for the orbital periods can be made more precise by taking into account dynamical stability considerations. We also calculate the distribution of stellar reflex velocities expected for this system, and show that it provides a good target for future radial velocity observations. If a precise orbital period can be determined for the outer Jovian planet through future observations, it will be an excellent candidate for follow-up transit observations to study its atmosphere and measure its oblateness.

[1]  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.

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

[3]  Adam L. Kraus,et al.  ZODIACAL EXOPLANETS IN TIME (ZEIT). I. A NEPTUNE-SIZED PLANET ORBITING AN M4.5 DWARF IN THE HYADES STAR CLUSTER , 2015, 1512.00483.

[4]  Jennifer C. Yee,et al.  Characterizing Long-Period Transiting Planets Observed by Kepler , 2008, 0805.1936.

[5]  Constraining the Oblateness of Kepler Planets , 2014, 1410.0361.

[6]  Robert L. Kurucz,et al.  Model Atmospheres for Population Synthesis , 1992 .

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

[8]  F. Fressin,et al.  THE FALSE POSITIVE RATE OF KEPLER AND THE OCCURRENCE OF PLANETS , 2013, 1301.0842.

[9]  Drake Deming,et al.  THE TRANSITING EXOPLANET SURVEY SATELLITE: SIMULATIONS OF PLANET DETECTIONS AND ASTROPHYSICAL FALSE POSITIVES , 2015, 1506.03845.

[10]  K. Kinemuchi,et al.  ALMOST ALL OF KEPLER'S MULTIPLE-PLANET CANDIDATES ARE PLANETS , 2012, 1201.5424.

[11]  Timothy D. Morton,et al.  THE RADIUS DISTRIBUTION OF PLANETS AROUND COOL STARS , 2013, 1303.3013.

[12]  K. Covey,et al.  CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS , 2012, 1201.2189.

[13]  D. Hogg,et al.  EXOPLANET POPULATION INFERENCE AND THE ABUNDANCE OF EARTH ANALOGS FROM NOISY, INCOMPLETE CATALOGS , 2014, 1406.3020.

[14]  Gregory Laughlin,et al.  ON THE ANOMALOUS RADII OF THE TRANSITING EXTRASOLAR PLANETS , 2011, 1101.5827.

[15]  Howard Isaacson,et al.  Kepler-47: A Transiting Circumbinary Multiplanet System , 2012, Science.

[16]  David M. Kipping,et al.  Parametrizing the exoplanet eccentricity distribution with the beta distribution. , 2013, 1306.4982.

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

[18]  J. Chambers.  A hybrid symplectic integrator that permits close encounters between massive bodies , 1999 .

[19]  D. Charbonneau,et al.  THE OCCURRENCE RATE OF SMALL PLANETS AROUND SMALL STARS , 2013, 1302.1647.

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

[21]  B. J. Fulton,et al.  A NEARBY M STAR WITH THREE TRANSITING SUPER-EARTHS DISCOVERED BY K2 , 2015, 1501.03798.

[22]  Howard Isaacson,et al.  ELEVEN MULTIPLANET SYSTEMS FROM K2 CAMPAIGNS 1 AND 2 AND THE MASSES OF TWO HOT SUPER-EARTHS , 2015, 1511.09213.

[23]  J. B. Laird,et al.  An abundance of small exoplanets around stars with a wide range of metallicities , 2012, Nature.

[24]  John C. Geary,et al.  Kepler-36: A Pair of Planets with Neighboring Orbits and Dissimilar Densities , 2012, Science.

[25]  John Asher Johnson,et al.  ROBOTIC LASER ADAPTIVE OPTICS IMAGING OF 715 KEPLER EXOPLANET CANDIDATES USING ROBO-AO , 2013, 1312.4958.

[26]  F. Faedi,et al.  Single transit candidates from K2: detection and period estimation , 2015, 1512.03722.

[27]  J. Fortney,et al.  THE TRANSIT TRANSMISSION SPECTRUM OF A COLD GAS GIANT PLANET , 2015, 1510.03430.

[28]  J. Winn,et al.  EMPIRICAL CONSTRAINTS ON THE OBLATENESS OF AN EXOPLANET , 2009, 0912.1594.

[29]  L. Pasquini,et al.  Basic physical parameters of a selected sample of evolved stars , 2006 .

[30]  A. Vanderburg,et al.  A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission , 2014, 1408.3853.

[31]  E. Ford,et al.  A FIRST COMPARISON OF KEPLER PLANET CANDIDATES IN SINGLE AND MULTIPLE SYSTEMS , 2011, 1103.3896.

[32]  F. Adams,et al.  Oscillations of relative inclination angles in compact extrasolar planetary systems , 2015, 1511.00009.

[33]  Discovery of a Transiting Planet Near the Snow-Line , 2014, 1407.4807.

[34]  Jason H. Steffen,et al.  The period ratio distribution of Kepler's candidate multiplanet systems , 2014, 1409.3320.

[35]  E. Ford,et al.  Characterizing the Orbital Eccentricities of Transiting Extrasolar Planets with Photometric Observations , 2008, 0801.2591.

[36]  Khadeejah A. Zamudio,et al.  PLANETARY CANDIDATES OBSERVED BY KEPLER. VII. THE FIRST FULLY UNIFORM CATALOG BASED ON THE ENTIRE 48-MONTH DATA SET (Q1–Q17 DR24) , 2015, 1512.06149.

[37]  T. Hirano,et al.  CHARACTERIZATION OF THE KOI-94 SYSTEM WITH TRANSIT TIMING VARIATION ANALYSIS: IMPLICATION FOR THE PLANET–PLANET ECLIPSE , 2013, 1310.5771.

[38]  D. Kipping,et al.  Observational biases for transiting planets , 2016, 1603.05662.

[39]  G. Marcy,et al.  A PLATEAU IN THE PLANET POPULATION BELOW TWICE THE SIZE OF EARTH , 2013, 1304.0460.

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

[41]  R. D'iaz,et al.  Hot Jupiters with relatives: discovery of additional planets in orbit around WASP-41 and WASP-47 , 2015, 1509.07750.

[42]  D. Queloz,et al.  CHEOPS: A transit photometry mission for ESA's small mission programme , 2013, 1305.2270.

[43]  G. Marcy,et al.  Prevalence of Earth-size Planets Orbiting Sun-like Stars , 2015, 1510.03902.

[44]  J. Steffen.  Sensitivity bias in the mass-radius distribution from transit timing variations and radial velocity measurements , 2015, 1510.04750.

[45]  Mean Motion Resonances in Exoplanet Systems: An Investigation into Nodding Behavior , 2012, 1211.3078.

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

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

[48]  S. Csizmadia,et al.  THE PLANETARY SYSTEM TO KIC 11442793: A COMPACT ANALOGUE TO THE SOLAR SYSTEM , 2013, 1310.6248.

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

[50]  Aisey M Andel.  ANALYTIC LIGHTCURVES FOR PLANETARY TRANSIT SEARCHES , 2002 .

[51]  L. Buchhave,et al.  Three regimes of extrasolar planet radius inferred from host star metallicities , 2014, Nature.

[52]  Mark Clampin,et al.  INFRARED TRANSMISSION SPECTROSCOPY OF THE EXOPLANETS HD 209458b AND XO-1b USING THE WIDE FIELD CAMERA-3 ON THE HUBBLE SPACE TELESCOPE , 2013, 1302.1141.

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

[54]  Joshua N. Winn,et al.  Transits and Occultations , 2010, 1001.2010.

[55]  M. Tamura,et al.  THE K2-ESPRINT PROJECT III: A CLOSE-IN SUPER-EARTH AROUND A METAL-RICH MID-M DWARF , 2015, 1511.08508.

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

[57]  Atmospheric Lensing and Oblateness Effects during an Extrasolar Planetary Transit , 2001, astro-ph/0103329.

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

[59]  E. Ford,et al.  Identifying non-resonant Kepler planetary systems , 2011, 1111.0299.

[60]  Howard Isaacson,et al.  TWO TRANSITING EARTH-SIZE PLANETS NEAR RESONANCE ORBITING A NEARBY COOL STAR , 2015, 1507.08256.

[61]  Stephen A. Shectman,et al.  The Carnegie Planet Finder Spectrograph: integration and commissioning , 2010, Astronomical Telescopes + Instrumentation.

[62]  F. Adams,et al.  WASP-47: A HOT JUPITER SYSTEM WITH TWO ADDITIONAL PLANETS DISCOVERED BY K2 , 2015, 1508.02411.

[63]  M. Couture,et al.  HIRES: the high-resolution echelle spectrometer on the Keck 10-m Telescope , 1994, Astronomical Telescopes and Instrumentation.

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

[65]  C. Henze,et al.  A TRANSITING JUPITER ANALOG , 2016, 1603.00042.

[66]  Hans Kristian Otnes Berge,et al.  PLANET HUNTERS. VIII. CHARACTERIZATION OF 41 LONG-PERIOD EXOPLANET CANDIDATES FROM KEPLER ARCHIVAL DATA , 2015, 1512.02559.

[67]  S. Seager,et al.  Constraining the Rotation Rate of Transiting Extrasolar Planets by Oblateness Measurements , 2002, astro-ph/0204225.

[68]  C. Lintott,et al.  PLANET HUNTERS. VI. AN INDEPENDENT CHARACTERIZATION OF KOI-351 AND SEVERAL LONG PERIOD PLANET CANDIDATES FROM THE KEPLER ARCHIVAL DATA , 2013, 1310.5912.

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

[70]  A. Szentgyorgyi,et al.  THE MASS OF Kepler-93b AND THE COMPOSITION OF TERRESTRIAL PLANETS , 2014, 1412.8687.

[71]  Howard Isaacson,et al.  THE MASS OF KOI-94d AND A RELATION FOR PLANET RADIUS, MASS, AND INCIDENT FLUX , 2013, 1303.2150.

[72]  P. Berlind,et al.  PLANETARY CANDIDATES FROM THE FIRST YEAR OF THE K2 MISSION , 2015, 1511.07820.

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

[74]  M. R. Haas,et al.  Kepler Mission Design, Realized Photometric Performance, and Early Science , 2010, 1001.0268.

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

[76]  D. Kipping.  Bayesian priors for the eccentricity of transiting planets , 2014, 1408.1393.

[77]  Jaymie M. Matthews,et al.  CHARACTERIZING K2 PLANET DISCOVERIES: A SUPER-EARTH TRANSITING THE BRIGHT K DWARF HIP 116454 , 2014, 1412.5674.

[78]  Sara Seager,et al.  A PRECISE WATER ABUNDANCE MEASUREMENT FOR THE HOT JUPITER WASP-43b , 2014, 1410.2255.

[79]  M. R. Haas,et al.  TERRESTRIAL PLANET OCCURRENCE RATES FOR THE KEPLER GK DWARF SAMPLE , 2015, 1506.04175.

[80]  Mark Clampin,et al.  Transiting Exoplanet Survey Satellite , 2014, 1406.0151.

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

[82]  Vanessa P. Bailey,et al.  TWO SMALL TEMPERATE PLANETS TRANSITING NEARBY M DWARFS IN K2 CAMPAIGNS 0 AND 1 , 2016, 1601.02706.

[83]  Pravin Chordia,et al.  HIGH-EFFICIENCY AUTONOMOUS LASER ADAPTIVE OPTICS , 2014, 1407.8179.