ON THE FREQUENCY OF POTENTIAL VENUS ANALOGS FROM KEPLER DATA

The field of exoplanetary science has seen a dramatic improvement in sensitivity to terrestrial planets over recent years. Such discoveries have been a key feature of results from the Kepler mission which utilizes the transit method to determine the size of the planet. These discoveries have resulted in a corresponding interest in the topic of the Habitable Zone and the search for potential Earth analogs. Within the solar system, there is a clear dichotomy between Venus and Earth in terms of atmospheric evolution, likely the result of the large difference (approximately a factor of two) in incident flux from the Sun. Since Venus is 95% of the Earth's radius in size, it is impossible to distinguish between these two planets based only on size. In this Letter we discuss planetary insolation in the context of atmospheric erosion and runaway greenhouse limits for planets similar to Venus. We define a ''Venus Zone'' in which the planet is more likely to be a Venus analog rather than an Earth analog. We identify 43 potential Venus analogs with an occurrence rate (η{sub ♀}) of 0.32{sub −0.07}{sup +0.05} and 0.45{sub −0.09}{sup +0.06} for M dwarfs and GK dwarfs, respectively.

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

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

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

[4]  Dorian S. Abbot,et al.  STABILIZING CLOUD FEEDBACK DRAMATICALLY EXPANDS THE HABITABLE ZONE OF TIDALLY LOCKED PLANETS , 2013, 1307.0515.

[5]  R. Gilliland,et al.  REVISION OF EARTH-SIZED KEPLER PLANET CANDIDATE PROPERTIES WITH HIGH-RESOLUTION IMAGING BY THE HUBBLE SPACE TELESCOPE , 2014, 1407.1057.

[6]  Jonathan J. Fortney,et al.  HOW THERMAL EVOLUTION AND MASS-LOSS SCULPT POPULATIONS OF SUPER-EARTHS AND SUB-NEPTUNES: APPLICATION TO THE KEPLER-11 SYSTEM AND BEYOND , 2012, 1205.0010.

[7]  Wesley A. Traub,et al.  TERRESTRIAL, HABITABLE-ZONE EXOPLANET FREQUENCY FROM KEPLER , 2011, 1109.4682.

[8]  Franck Selsis,et al.  3D climate modeling of close-in land planets: Circulation patterns, climate moist bistability and habitability , 2013, 1303.7079.

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

[10]  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.

[11]  Debra A. Fischer,et al.  The Exoplanet Orbit Database , 2010, 1012.5676.

[12]  X. Delfosse,et al.  Habitable planets around the star Gliese 581 , 2007, 0710.5294.

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

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

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

[16]  Ryan C. Terrien,et al.  HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: NEW ESTIMATES , 2013, 1301.6674.

[17]  E. Agol,et al.  VALIDATION OF KEPLER'S MULTIPLE PLANET CANDIDATES. II. REFINED STATISTICAL FRAMEWORK AND DESCRIPTIONS OF SYSTEMS OF SPECIAL INTEREST , 2014, 1402.6352.

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

[19]  M. R. Haas,et al.  A SUPER-EARTH-SIZED PLANET ORBITING IN OR NEAR THE HABITABLE ZONE AROUND A SUN-LIKE STAR , 2013, The Astrophysical Journal.

[20]  F Forget,et al.  Warming early Mars with carbon dioxide clouds that scatter infrared radiation. , 1997, Science.

[21]  Stephen R. Kane,et al.  Constraining Orbital Parameters through Planetary Transit Monitoring , 2008, 0808.1890.

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

[23]  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.

[24]  T. Barclay,et al.  A POTENTIAL SUPER-VENUS IN THE KEPLER-69 SYSTEM , 2013, 1305.2933.

[25]  J. Kasting,et al.  Habitable zones around main sequence stars. , 1993, Icarus.

[26]  Arnold Hanslmeier,et al.  The CoRoT space mission : early results Special feature Determining the mass loss limit for close-in exoplanets : what can we learn from transit observations ? , 2009 .

[27]  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.

[28]  J. Fortney,et al.  THE ROLE OF CORE MASS IN CONTROLLING EVAPORATION: THE KEPLER RADIUS DISTRIBUTION AND THE KEPLER-36 DENSITY DICHOTOMY , 2013, 1305.0269.

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

[30]  Stephen R. Kane,et al.  The Habitable Zone Gallery , 2012, 1202.2377.

[31]  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.

[32]  Stephen R. Kane,et al.  HABITABLE ZONE DEPENDENCE ON STELLAR PARAMETER UNCERTAINTIES , 2014, 1401.3349.