Exploring exoplanet populations with NASA’s Kepler Mission

The Kepler Mission is exploring the diversity of planets and planetary systems. Its legacy will be a catalog of discoveries sufficient for computing planet occurrence rates as a function of size, orbital period, star type, and insolation flux. The mission has made significant progress toward achieving that goal. Over 3,500 transiting exoplanets have been identified from the analysis of the first 3 y of data, 100 planets of which are in the habitable zone. The catalog has a high reliability rate (85–90% averaged over the period/radius plane), which is improving as follow-up observations continue. Dynamical (e.g., velocimetry and transit timing) and statistical methods have confirmed and characterized hundreds of planets over a large range of sizes and compositions for both single- and multiple-star systems. Population studies suggest that planets abound in our galaxy and that small planets are particularly frequent. Here, I report on the progress Kepler has made measuring the prevalence of exoplanets orbiting within one astronomical unit of their host stars in support of the National Aeronautics and Space Administration’s long-term goal of finding habitable environments beyond the solar system.

[1]  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.

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

[3]  David M. Kipping,et al.  THE HUNT FOR EXOMOONS WITH KEPLER (HEK). IV. A SEARCH FOR MOONS AROUND EIGHT M DWARFS , 2014, 1401.1210.

[4]  Planets Formed in Habitable Zones of M Dwarf Stars Probably Are Deficient in Volatiles , 2007, astro-ph/0703576.

[5]  D. Lin,et al.  Toward a Deterministic Model of Planetary Formation. I. A Desert in the Mass and Semimajor Axis Distributions of Extrasolar Planets , 2004 .

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

[7]  Jon M. Jenkins,et al.  MEASURING TRANSIT SIGNAL RECOVERY IN THE KEPLER PIPELINE. III. COMPLETENESS OF THE Q1–Q17 DR24 PLANET CANDIDATE CATALOG WITH IMPORTANT CAVEATS FOR OCCURRENCE RATE CALCULATIONS , 2016, 1605.05729.

[8]  Dorian S. Abbot,et al.  STRONG DEPENDENCE OF THE INNER EDGE OF THE HABITABLE ZONE ON PLANETARY ROTATION RATE , 2014, 1404.4992.

[9]  Francois Forget,et al.  Increased insolation threshold for runaway greenhouse processes on Earth-like planets , 2013, Nature.

[10]  Sara Seager,et al.  TOWARD THE MINIMUM INNER EDGE DISTANCE OF THE HABITABLE ZONE , 2013, 1304.3714.

[11]  Khadeejah A. Zamudio,et al.  PLANETARY CANDIDATES OBSERVED BY KEPLER. V. PLANET SAMPLE FROM Q1–Q12 (36 MONTHS) , 2015, 1501.07286.

[12]  A. Prsa,et al.  PRE-SPECTROSCOPIC FALSE-POSITIVE ELIMINATION OF KEPLER PLANET CANDIDATES , 2010, 1001.0392.

[13]  P. Gaulme,et al.  Global asteroseismic properties of solar-like oscillations observed by Kepler: a comparison of complementary analysis methods , 2011, 1105.0571.

[14]  A. Santerne,et al.  The contribution of secondary eclipses as astrophysical false positives to exoplanet transit surveys , 2013, 1307.2003.

[15]  TOWARD A DETERMINISTIC MODEL OF PLANETARY FORMATION . I . A DESERT IN THE MASS AND SEMIMAJOR AXIS DISTRIBUTIONS OF EXTRASOLAR PLANETS , 2004 .

[16]  Andrew Szentgyorgyi,et al.  An Earth-sized planet with an Earth-like density , 2013, Nature.

[17]  E. Gaidos,et al.  THEY MIGHT BE GIANTS: LUMINOSITY CLASS, PLANET OCCURRENCE, AND PLANET–METALLICITY RELATION OF THE COOLEST KEPLER TARGET STARS , 2012, 1202.5394.

[18]  Norman H Sleep,et al.  Habitable zone limits for dry planets. , 2011, Astrobiology.

[19]  T. Brown,et al.  Detection of Planetary Transits Across a Sun-like Star , 1999, The Astrophysical journal.

[20]  William F. Welsh,et al.  KEPLER MISSION STELLAR AND INSTRUMENT NOISE PROPERTIES , 2011, 1107.5207.

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

[22]  Debra A. Fischer,et al.  Planet Hunters: New Kepler planet candidates from analysis of quarter 2 , 2013 .

[23]  Jon M. Jenkins,et al.  ARCHITECTURE AND DYNAMICS OF KEPLER'S CANDIDATE MULTIPLE TRANSITING PLANET SYSTEMS , 2011, 1102.0543.

[24]  Timothy M. Brown,et al.  KEPLER INPUT CATALOG: PHOTOMETRIC CALIBRATION AND STELLAR CLASSIFICATION , 2011, 1102.0342.

[25]  Jie Li,et al.  Data validation in the Kepler Science Operations Center pipeline , 2010, Astronomical Telescopes + Instrumentation.

[26]  R. P. Butler,et al.  A Transiting “51 Peg-like” Planet , 2000, The Astrophysical journal.

[27]  Russel J. White,et al.  A SURVEY OF STELLAR FAMILIES: MULTIPLICITY OF SOLAR-TYPE STARS , 2009, 1007.0414.

[28]  C. Moutou,et al.  SOPHIE velocimetry of Kepler transit candidates II. KOI-428b: a hot Jupiter transiting a subgiant F-star , 2010, 1101.0196.

[29]  John C. Geary,et al.  Alignment of the stellar spin with the orbits of a three-planet system , 2012, Nature.

[30]  Howard Isaacson,et al.  Kepler-9: A System of Multiple Planets Transiting a Sun-Like Star, Confirmed by Timing Variations , 2010, Science.

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

[32]  Zhaohuan Zhu,et al.  FAST RISE OF “NEPTUNE-SIZE” PLANETS (4–8 R⊕) FROM P ∼ 10 TO ∼250 DAYS—STATISTICS OF KEPLER PLANET CANDIDATES UP TO ∼0.75 AU , 2012, 1212.4853.

[33]  M. R. Haas,et al.  MASSES, RADII, AND ORBITS OF SMALL KEPLER PLANETS: THE TRANSITION FROM GASEOUS TO ROCKY PLANETS , 2014, 1401.4195.

[34]  M. R. Haas,et al.  INITIAL CHARACTERISTICS OF KEPLER LONG CADENCE DATA FOR DETECTING TRANSITING PLANETS , 2010, 1001.0256.

[35]  William F. Welsh,et al.  KEPLER ECLIPSING BINARY STARS. II. 2165 ECLIPSING BINARIES IN THE SECOND DATA RELEASE , 2011, 1103.1659.

[36]  Shawn Domagal-Goldman,et al.  HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: DEPENDENCE ON PLANETARY MASS , 2014, 1404.5292.

[37]  G. Montagnier,et al.  KOI-200 b and KOI-889 b: Two transiting exoplanets detected and characterized with Kepler, SOPHIE, and HARPS-N , 2013, 1304.6002.

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

[39]  Yanqin Wu,et al.  DENSITY AND ECCENTRICITY OF KEPLER PLANETS , 2012, 1210.7810.

[40]  Jack J. Lissauer,et al.  KEPLER-79'S LOW DENSITY PLANETS , 2013, 1310.2642.

[41]  E. Gaidos,et al.  OBJECTS IN KEPLER'S MIRROR MAY BE LARGER THAN THEY APPEAR: BIAS AND SELECTION EFFECTS IN TRANSITING PLANET SURVEYS , 2012, 1211.2279.

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

[43]  Jon M. Jenkins,et al.  The Impact of Solar-like Variability on the Detectability of Transiting Terrestrial Planets , 2002 .

[44]  Howard Isaacson,et al.  TRANSIT TIMING OBSERVATIONS FROM KEPLER. II. CONFIRMATION OF TWO MULTIPLANET SYSTEMS VIA A NON-PARAMETRIC CORRELATION ANALYSIS , 2012, 1201.5409.

[45]  Howard Isaacson,et al.  KEPLER-18b, c, AND d: A SYSTEM OF THREE PLANETS CONFIRMED BY TRANSIT TIMING VARIATIONS, LIGHT CURVE VALIDATION, WARM-SPITZER PHOTOMETRY, AND RADIAL VELOCITY MEASUREMENTS , 2011, 1110.0820.

[46]  Nuno C. Santos,et al.  Extrasolar Planets: Statistical properties of exoplanets , 2007 .

[47]  Austin,et al.  KEPLER'S FIRST ROCKY PLANET: KEPLER-10b , 2011, 1102.0605.

[48]  Howard Isaacson,et al.  An Earth-Sized Planet in the Habitable Zone of a Cool Star , 2014, Science.

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

[50]  Jie Li,et al.  Kepler-22b: A 2.4 EARTH-RADIUS PLANET IN THE HABITABLE ZONE OF A SUN-LIKE STAR , 2011, The Astrophysical Journal.

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

[52]  F. Fressin,et al.  KEPLER-14b: A MASSIVE HOT JUPITER TRANSITING AN F STAR IN A CLOSE VISUAL BINARY , 2011, 1106.5510.

[53]  S. Ida,et al.  Towards a Deterministic Model of Planetary Formation I: a Desert in the Mass and Semi Major Axis Distributions of Extra Solar Planets , 2022 .

[54]  Travis S. Metcalfe,et al.  A REVISED EFFECTIVE TEMPERATURE SCALE FOR THE KEPLER INPUT CATALOG , 2011, 1110.4456.

[55]  A. Ofir,et al.  An independent planet search in the Kepler dataset - II. An extremely low-density super-Earth mass planet around Kepler-87 , 2013, 1310.2064.

[56]  C. Moutou,et al.  SOPHIE velocimetry of Kepler transit candidates VII. A false-positive rate of 35% for Kepler close-in giant candidates , 2012, 1206.0601.

[57]  Jiwei Xie.  Transit Timing Variation of Near-Resonance Planetary Pairs. II. Confirmation of 30 planets in 15 Multiple Planet Systems , 2013, 1309.2329.

[58]  M. R. Haas,et al.  TRANSIT TIMING OBSERVATIONS FROM KEPLER. IV. CONFIRMATION OF FOUR MULTIPLE-PLANET SYSTEMS BY SIMPLE PHYSICAL MODELS , 2012, 1201.5415.

[59]  Eric Gaidos,et al.  CANDIDATE PLANETS IN THE HABITABLE ZONES OF KEPLER STARS , 2013, 1301.2384.

[60]  R. Kopparapu,et al.  A REVISED ESTIMATE OF THE OCCURRENCE RATE OF TERRESTRIAL PLANETS IN THE HABITABLE ZONES AROUND KEPLER M-DWARFS , 2013, 1303.2649.

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

[62]  D. A. Caldwell,et al.  SELECTION, PRIORITIZATION, AND CHARACTERISTICS OF KEPLER TARGET STARS , 2010, 1001.0349.

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

[64]  Batavia,et al.  Transit timing observations from Kepler - III. : Confirmation of four multiple planet systems by a Fourier-domain study of anticorrelated transit timing variations , 2012, 1201.5412.

[65]  F. Fressin,et al.  EXOPLANET CHARACTERIZATION BY PROXY: A TRANSITING 2.15 R⊕ PLANET NEAR THE HABITABLE ZONE OF THE LATE K DWARF KEPLER-61 , 2013, The Astrophysical Journal.

[66]  Howard Isaacson,et al.  KEPLER-20: A SUN-LIKE STAR WITH THREE SUB-NEPTUNE EXOPLANETS AND TWO EARTH-SIZE CANDIDATES , 2011, 1112.4514.

[67]  Las Cumbres Observatory Global Telescope Network,et al.  PLANETARY CANDIDATES OBSERVED BY KEPLER. III. ANALYSIS OF THE FIRST 16 MONTHS OF DATA , 2012, 1202.5852.

[68]  John Asher Johnson,et al.  ON THE LOW FALSE POSITIVE PROBABILITIES OF KEPLER PLANET CANDIDATES , 2011, 1101.5630.

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

[70]  Howard Isaacson,et al.  A rocky composition for an Earth-sized exoplanet , 2013, Nature.

[71]  James F Kasting,et al.  Remote life-detection criteria, habitable zone boundaries, and the frequency of Earth-like planets around M and late K stars , 2013, Proceedings of the National Academy of Sciences.

[72]  Megan E. Schwamb,et al.  PLANET HUNTERS: A TRANSITING CIRCUMBINARY PLANET IN A QUADRUPLE STAR SYSTEM , 2012, 1210.3612.

[73]  Tx,et al.  Transit timing observations from Kepler - VII. Confirmation of 27 planets in 13 multiplanet systems via transit timing variations and orbital stability , 2012, 1208.3499.

[74]  Roger C. Hunter,et al.  Detection of Potential Transit Signals in 16 Quarters of Kepler Mission Data , 2013 .

[75]  Howard Isaacson,et al.  ALL SIX PLANETS KNOWN TO ORBIT KEPLER-11 HAVE LOW DENSITIES , 2013, 1303.0227.

[76]  Joseph D. Twicken,et al.  Likely Planet Candidates Identified by Machine Learning Applied to Four Years of Kepler Data , 2014 .

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

[78]  Howard Isaacson,et al.  Kepler-62: A Five-Planet System with Planets of 1.4 and 1.6 Earth Radii in the Habitable Zone , 2013, Science.

[79]  Jon M. Jenkins,et al.  MEASURING TRANSIT SIGNAL RECOVERY IN THE KEPLER PIPELINE. I. INDIVIDUAL EVENTS , 2013, 1303.0255.

[80]  Ji-Wei Xie,et al.  Transit Timing Variation of Near-resonance Planetary Pairs: Confirmation of 12 Multiple-planet Systems , 2012, 1208.3312.

[81]  Jaymie M. Matthews,et al.  REVISED STELLAR PROPERTIES OF KEPLER TARGETS FOR THE QUARTER 1–16 TRANSIT DETECTION RUN , 2013, 1312.0662.

[82]  A. Ofir,et al.  An independent planet search in the Kepler dataset - I. One hundred new candidates and revised Kepler objects of interest , 2012, 1206.5347.

[83]  M. R. Haas,et al.  PLANETARY CANDIDATES OBSERVED BY KEPLER IV: PLANET SAMPLE FROM Q1-Q8 (22 MONTHS) , 2014 .

[84]  A. Santerne,et al.  SOPHIE velocimetry of Kepler transit candidates - V. The three hot Jupiters KOI-135b, KOI-204b, and KOI-203b (alias Kepler-17b) , 2011, 1110.5462.

[85]  T. Guillot,et al.  SOPHIE velocimetry of Kepler transit candidates III. KOI-423b: an 18 Mjup transiting companion around an F7IV star , 2011, 1106.3225.

[86]  Sara Seager,et al.  KEPLER ECLIPSING BINARY STARS. I. CATALOG AND PRINCIPAL CHARACTERIZATION OF 1879 ECLIPSING BINARIES IN THE FIRST DATA RELEASE , 2010, 1006.2815.

[87]  Peter Tenenbaum,et al.  Identification of Background False Positives from Kepler Data , 2013, 1303.0052.

[88]  M. R. Haas,et al.  A closely packed system of low-mass, low-density planets transiting Kepler-11 , 2011, Nature.

[89]  Megan E. Schwamb,et al.  PLANET HUNTERS. V. A CONFIRMED JUPITER-SIZE PLANET IN THE HABITABLE ZONE AND 42 PLANET CANDIDATES FROM THE KEPLER ARCHIVE DATA , 2013, 1301.0644.

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

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

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

[93]  F. Fressin,et al.  CHARACTERISTICS OF KEPLER PLANETARY CANDIDATES BASED ON THE FIRST DATA SET , 2010, 1006.2799.

[94]  E. Ford,et al.  KEPLER-15b: A HOT JUPITER ENRICHED IN HEAVY ELEMENTS AND THE FIRST KEPLER MISSION PLANET CONFIRMED WITH THE HOBBY–EBERLY TELESCOPE , 2011 .

[95]  James P. Lloyd,et al.  CHARACTERIZING THE COOL KEPLER OBJECTS OF INTERESTS. NEW EFFECTIVE TEMPERATURES, METALLICITIES, MASSES, AND RADII OF LOW-MASS KEPLER PLANET-CANDIDATE HOST STARS , 2011, 1109.1819.