Christopher E. Henze

University of Copenhagen, København, Capital Region, Denmark

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Publications (20)280.77 Total impact

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    ABSTRACT: In most theories of planet formation, the snow-line represents a boundary between the emergence of the interior rocky planets and the exterior ice giants. The wide separation of the snow-line makes the discovery of transiting worlds challenging, yet transits would allow for detailed subsequent characterization. We present the discovery of Kepler-421b, a Uranus-sized exoplanet transiting a G9/K0 dwarf once every 704.2 days in a near-circular orbit. Using public Kepler photometry, we demonstrate that the two observed transits can be uniquely attributed to the 704.2 day period. Detailed light curve analysis with BLENDER validates the planetary nature of Kepler-421b to >4 sigmas confidence. Kepler-421b receives the same insolation as a body at ~2AU in the Solar System and for a Uranian albedo would have an effective temperature of ~180K. Using a time-dependent model for the protoplanetary disk, we estimate that Kepler-421b's present semi-major axis was beyond the snow-line after ~3Myr, indicating that Kepler-421b may have formed at its observed location.
    The Astrophysical Journal 07/2014; 795(1). · 6.73 Impact Factor
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    ABSTRACT: The quest for Earth-like planets is a major focus of current exoplanet research. Although planets that are Earth-sized and smaller have been detected, these planets reside in orbits that are too close to their host star to allow liquid water on their surfaces. We present the detection of Kepler-186f, a 1.11 ± 0.14 Earth-radius planet that is the outermost of five planets, all roughly Earth-sized, that transit a 0.47 ± 0.05 solar-radius star. The intensity and spectrum of the star's radiation place Kepler-186f in the stellar habitable zone, implying that if Kepler-186f has an Earth-like atmosphere and water at its surface, then some of this water is likely to be in liquid form.
    Science 04/2014; 344(6181):277-80. · 31.20 Impact Factor
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    ABSTRACT: We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology, we establish low false-positive probabilities for all of the transiting planets (41 of 42 have a false-positive probability under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than 3X the size of Earth. For 16 planets, the Doppler signal was securely detected, providing a direct measurement of the planet's mass. For the other 26 planets we provide either marginal mass measurements or upper limits to their masses and densities; in many cases we can rule out a rocky composition. We identify 6 planets with densities above 5 g/cc, suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than ~2 R_earth. Larger planets evidently contain a larger fraction of low-density material (H, He, and H2O).
    01/2014;
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    ABSTRACT: We provide updates to the Kepler planet candidate sample based upon nearly two years of high-precision photometry (i.e., Q1-Q8). From an initial list of nearly 13,400 Threshold Crossing Events (TCEs), 480 new host stars are identified from their flux time series as consistent with hosting transiting planets. Potential transit signals are subjected to further analysis using the pixel-level data, which allows background eclipsing binaries to be identified through small image position shifts during transit. We also re-evaluate Kepler Objects of Interest (KOI) 1-1609, which were identified early in the mission, using substantially more data to test for background false positives and to find additional multiple systems. Combining the new and previous KOI samples, we provide updated parameters for 2,738 Kepler planet candidates distributed across 2,017 host stars. From the combined Kepler planet candidates, 472 are new from the Q1-Q8 data examined in this study. The new Kepler planet candidates represent ~40% of the sample with Rp~1 Rearth and represent ~40% of the low equilibrium temperature (Teq<300 K) sample. We review the known biases in the current sample of Kepler planet candidates relevant to evaluating planet population statistics with the current Kepler planet candidate sample.
    The Astrophysical Journal Supplement Series 12/2013; 210(2). · 16.24 Impact Factor
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    ABSTRACT: Most stars and their planets form in open clusters. Over 95 per cent of such clusters have stellar densities too low (less than a hundred stars per cubic parsec) to withstand internal and external dynamical stresses and fall apart within a few hundred million years. Older open clusters have survived by virtue of being richer and denser in stars (1,000 to 10,000 per cubic parsec) when they formed. Such clusters represent a stellar environment very different from the birthplace of the Sun and other planet-hosting field stars. So far more than 800 planets have been found around Sun-like stars in the field. The field planets are usually the size of Neptune or smaller. In contrast, only four planets have been found orbiting stars in open clusters, all with masses similar to or greater than that of Jupiter. Here we report observations of the transits of two Sun-like stars by planets smaller than Neptune in the billion-year-old open cluster NGC6811. This demonstrates that small planets can form and survive in a dense cluster environment, and implies that the frequency and properties of planets in open clusters are consistent with those of planets around field stars in the Galaxy.
    Nature 06/2013; · 38.60 Impact Factor
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    ABSTRACT: We present the validation and characterization of Kepler-61b: a 2.15 R_Earth planet orbiting near the inner edge of the habitable zone of a low-mass star. Our characterization of the host star Kepler-61 is based upon a comparison with the set of spectroscopically similar stars with directly-measured radii and temperatures. We apply a stellar prior drawn from the weighted mean of these properties, in tandem with the Kepler photometry, to infer a planetary radius for Kepler-61b of 2.15+/-0.13 R_Earth and an equilibrium temperature of 273+/-13 K (given its period of 59.87756+/-0.00020 days and assuming a planetary albedo of 0.3). The technique of leveraging the physical properties of nearby "proxy" stars allows for an independent check on stellar characterization via the traditional measurements with stellar spectra and evolutionary models. In this case, such a check had implications for the putative habitability of Kepler-61b: the planet is 10% warmer and larger than inferred from K-band spectral characterization. From the Kepler photometry, we estimate a stellar rotation period of 36 days, which implies a stellar age of >1 Gyr. We summarize the evidence for the planetary nature of the Kepler-61 transit signal, which we conclude is 30,000 times more likely to be due to a planet than a blend scenario. Finally, we discuss possible compositions for Kepler-61b with a comparison to theoretical models as well as to known exoplanets with similar radii and dynamically measured masses.
    The Astrophysical Journal 04/2013; 773(2). · 6.73 Impact Factor
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    ABSTRACT: We present the detection of five planets-Kepler-62b, c, d, e, and f-of size 1.31, 0.54, 1.95, 1.61 and 1.41 Earth radii (R⊕), orbiting a K2V star at periods of 5.7, 12.4, 18.2, 122.4, and 267.3 days, respectively. The outermost planets (Kepler-62e and -62f) are super-Earth-size (1.25 < planet radius ≤ 2.0 R⊕) planets in the habitable zone (HZ) of their host star, receiving 1.2 ± 0.2 and 0.41 ± 0.05 times the solar flux at Earth's orbit (S⊙). Theoretical models of Kepler-62e and -62f for a stellar age of ~7 Gyr suggest that both planets could be solid, either with a rocky composition or composed of mostly solid water in their bulk.
    Science 04/2013; · 31.20 Impact Factor
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    ABSTRACT: Since the discovery of the first exoplanets, it has been known that other planetary systems can look quite unlike our own. Until fairly recently, we have been able to probe only the upper range of the planet size distribution, and, since last year, to detect planets that are the size of Earth or somewhat smaller. Hitherto, no planets have been found that are smaller than those we see in the Solar System. Here we report a planet significantly smaller than Mercury. This tiny planet is the innermost of three that orbit the Sun-like host star, which we have designated Kepler-37. Owing to its extremely small size, similar to that of the Moon, and highly irradiated surface, the planet, Kepler-37b, is probably rocky with no atmosphere or water, similar to Mercury.
    Nature 02/2013; 494(7438):452-4. · 38.60 Impact Factor
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    ABSTRACT: We present the validation and characterization of Kepler-61b: a 2.5 R_Earth planet orbiting near the inner edge of the habitable zone of a low-mass star. Our characterization of the host star Kepler-61 is based upon our identification of a spectroscopically similar star located 4.9 pc from Earth. This proxy star to Kepler-61 has a published direct interferometric radius and effective temperature measurement, which we apply in tandem with the Kepler photometry to characterize the planet Kepler-61b. The technique of identifying a nearby proxy star with directly measured properties allows for an independent check on stellar characterization via the traditional measurements with stellar spectra and evolutionary models. In this case, such a check had profound implications for the putative habitability of Kepler-61b. This work was performed in part under contract with the California Institute of Technology (Caltech) funded by NASA through the Sagan Fellowship Program
    01/2013;
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    ABSTRACT: NASA’s Kepler Space Telescope has collected data on over 190,000 targets (and counting) since launch on March 6th, 2009, resulting in a growing dataset that must be processed by the Kepler Science Pipeline. The algorithms that make up the pipeline are responsible for clearing the chaff of instrumental and astrophysical noise to detect and model the transit-like signals hidden underneath. We discuss how the Kepler pipeline infrastructure has evolved to meet the growing computational needs of these algorithms. The algorithms and other support software that make up the pipeline were largely developed before launch and tested with simulated data. When confronted with flight data from the Kepler instrument, the pipeline revealed that the higher than expected thermal sensitivity of the instrument, electronics noise and operational procedures all introduced artifacts to the data at levels comparable to, or higher than the sought after transit signals. In the months after launch the team of pipeline developers at the Kepler Science Operations Center (SOC) at NASA Ames Research Center toiled to update the pipeline software to identify and mitigate these artifacts where possible, work that continues today. The increase in complexity caused by these algorithm changes, along with a need for regular reprocessing of a growing dataset to support scientific data analysis and pipeline development created an increasing demand for computing resources. This need in turn drove the need for changes to the pipeline infrastructure software to extend pipeline algorithm execution to NASA’s Advanced Supercomputer (NAS). Use of the NAS as a computing resource allows the pipeline operator to spread the planetary transit search and data validation jobs across tens of thousands of processing cores. With a possible extended mission on the horizon, this need will only grow, and work to port the rest of the pipeline to the NAS has already begun.
    05/2012;
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    ABSTRACT: We present Kepler observations of the bright (V=8.3), oscillating star HD 179070. The observations show transit-like events which reveal that the star is orbited every 2.8 days by a small, 1.6 R_Earth object. Seismic studies of HD 179070 using short cadence Kepler observations show that HD 179070 has a frequency power spectrum consistent with solar-like oscillations that are acoustic p-modes. Asteroseismic analysis provides robust values for the mass and radius of HD 179070, 1.34{\pm}0.06 M{\circ} and 1.86{\pm}0.04 R{\circ} respectively, as well as yielding an age of 2.84{\pm}0.34 Gyr for this F5 subgiant. Together with ground-based follow-up observations, analysis of the Kepler light curves and image data, and blend scenario models, we conservatively show at the >99.7% confidence level (3{\sigma}) that the transit event is caused by a 1.64{\pm}0.04 R_Earth exoplanet in a 2.785755{\pm}0.000032 day orbit. The exoplanet is only 0.04 AU away from the star and our spectroscopic observations provide an upper limit to its mass of ~10 M_Earth (2-{\sigma}). HD 179070 is the brightest exoplanet host star yet discovered by Kepler.
    The Astrophysical Journal 02/2012; 746:123 (18pp). · 6.73 Impact Factor
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    ABSTRACT: The detection and characterization of the first transiting super-Earth, CoRoT-7 b, has required an unprecedented effort in terms of telescope time and analysis. Although the star does display a radial-velocity signal at the period of the planet, this has been difficult to disentangle from the intrinsic stellar variability and pinning down the velocity amplitude has been very challenging. As a result, the precise value of the mass of the planet—and even the extent to which it can be considered to be confirmed—has been debated in the recent literature, with six mass measurements published so far based on the same spectroscopic observations, ranging from about 2 to 8 Earth masses. Here we report on an independent validation of the planet discovery using one of the fundamental properties of a transit signal: its achromaticity. We observed four transits of CoRoT-7 b at 4.5 μm and 8.0 μm with the Infrared Array Camera (IRAC) on board the Spitzer Space Telescope in order to determine whether the depth of the transit signal in the near-infrared is consistent with that observed in the CoRoT bandpass, as expected for a planet. We detected the transit and found an average depth of 0.426 ± 0.115 mmag at 4.5 μm, which is in good agreement with the depth of 0.350 ± 0.011 mmag (ignoring limb darkening) found by CoRoT. The observations at 8.0 μm did not yield a significant detection. The 4.5 μm observations place important constraints on the kinds of astrophysical false positives that could mimic the signal. Combining this with additional constraints reported earlier, we performed an exhaustive exploration of possible blend scenarios for CoRoT-7 b using the BLENDER technique. We are able to rule out the vast majority of false positives, and the remaining ones are found to be much less likely than a true transiting planet. We thus validate CoRoT-7 b as a bona fide planet with a very high degree of confidence, independently of any radial-velocity information. Our Spitzer observations have additionally allowed us to significantly improve the ephemeris of the planet, so that future transits should be recoverable well into the next decade. In its warm phase Spitzer is expected to be an essential tool for the validation, along the lines of the present analysis, of transiting planet candidates with shallow signals from CoRoT as well as from the Kepler mission, including potentially rocky planets in the habitable zones of their parent stars.
    The Astrophysical Journal 12/2011; 745(1):81. · 6.73 Impact Factor
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    ABSTRACT: Since the discovery of the first extrasolar giant planets around Sun-like stars, evolving observational capabilities have brought us closer to the detection of true Earth analogues. The size of an exoplanet can be determined when it periodically passes in front of (transits) its parent star, causing a decrease in starlight proportional to its radius. The smallest exoplanet hitherto discovered has a radius 1.42 times that of the Earth's radius (R(⊕)), and hence has 2.9 times its volume. Here we report the discovery of two planets, one Earth-sized (1.03R(⊕)) and the other smaller than the Earth (0.87R(⊕)), orbiting the star Kepler-20, which is already known to host three other, larger, transiting planets. The gravitational pull of the new planets on the parent star is too small to measure with current instrumentation. We apply a statistical method to show that the likelihood of the planetary interpretation of the transit signals is more than three orders of magnitude larger than that of the alternative hypothesis that the signals result from an eclipsing binary star. Theoretical considerations imply that these planets are rocky, with a composition of iron and silicate. The outer planet could have developed a thick water vapour atmosphere.
    Nature 12/2011; 482(7384):195-8. · 38.60 Impact Factor
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    ABSTRACT: We present the discovery of the Kepler-20 planetary system, which we initially identified through the detection of five distinct periodic transit signals in the Kepler light curve of the host star 2MASSJ19104752+4220194. We find a stellar effective temperature Teff=5455+-100K, a metallicity of [Fe/H]=0.01+-0.04, and a surface gravity of log(g)=4.4+-0.1. Combined with an estimate of the stellar density from the transit light curves we deduce a stellar mass of Mstar=0.912+-0.034 Msun and a stellar radius of Rstar=0.944^{+0.060}_{-0.095} Rsun. For three of the transit signals, our results strongly disfavor the possibility that these result from astrophysical false positives. We conclude that the planetary scenario is more likely than that of an astrophysical false positive by a factor of 2e5 (Kepler-20b), 1e5 (Kepler-20c), and 1.1e3 (Kepler-20d), sufficient to validate these objects as planetary companions. For Kepler-20c and Kepler-20d, the blend scenario is independently disfavored by the achromaticity of the transit: From Spitzer data gathered at 4.5um, we infer a ratio of the planetary to stellar radii of 0.075+-0.015 (Kepler-20c) and 0.065+-0.011 (Kepler-20d), consistent with each of the depths measured in the Kepler optical bandpass. We determine the orbital periods and physical radii of the three confirmed planets to be 3.70d and 1.91^{+0.12}_{-0.21} Rearth for Kepler-20b, 10.85 d and 3.07^{+0.20}_{-0.31} Rearth for Kepelr-20c, and 77.61 d and 2.75^{+0.17}_{-0.30} Rearth for Kepler-20d. From multi-epoch radial velocities, we determine the masses of Kepler-20b and Kepler-20c to be 8.7\+-2.2 Mearth and 16.1+-3.5 Mearth, respectively, and we place an upper limit on the mass of Kepler-20d of 20.1 Mearth (2 sigma).
    The Astrophysical Journal 12/2011; 749(1). · 6.73 Impact Factor
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    ABSTRACT: A search of the time-series photometry from NASA's Kepler spacecraft reveals a transiting planet candidate orbiting the 11th magnitude G5 dwarf KIC 10593626 with a period of 290 days. The characteristics of the host star are well constrained by high-resolution spectroscopy combined with an asteroseismic analysis of the Kepler photometry, leading to an estimated mass and radius of 0.970 +/- 0.060 MSun and 0.979 +/- 0.020 RSun. The depth of 492 +/- 10ppm for the three observed transits yields a radius of 2.38 +/- 0.13 REarth for the planet. The system passes a battery of tests for false positives, including reconnaissance spectroscopy, high-resolution imaging, and centroid motion. A full BLENDER analysis provides further validation of the planet interpretation by showing that contamination of the target by an eclipsing system would rarely mimic the observed shape of the transits. The final validation of the planet is provided by 16 radial velocities obtained with HIRES on Keck 1 over a one year span. Although the velocities do not lead to a reliable orbit and mass determination, they are able to constrain the mass to a 3{\sigma} upper limit of 124 MEarth, safely in the regime of planetary masses, thus earning the designation Kepler-22b. The radiative equilibrium temperature is 262K for a planet in Kepler-22b's orbit. Although there is no evidence that Kepler-22b is a rocky planet, it is the first confirmed planet with a measured radius to orbit in the Habitable Zone of any star other than the Sun.
    The Astrophysical Journal 12/2011; 745(2). · 6.73 Impact Factor
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    ABSTRACT: We present the discovery of the Kepler-19 planetary system, which we first identified from a 9.3 day periodic transit signal in the Kepler photometry. From high-resolution spectroscopy of the star, we find a stellar effective temperature T eff = 5541 ± 60 K, a metallicity [Fe/H] = –0.13 ± 0.06, and a surface gravity log(g) = 4.59 ± 0.10. We combine the estimate of T eff and [Fe/H] with an estimate of the stellar density derived from the photometric light curve to deduce a stellar mass of M = 0.936 ± 0.040 M ☉ and a stellar radius of R = 0.850 ± 0.018 R ☉ (these errors do not include uncertainties in the stellar models). We rule out the possibility that the transits result from an astrophysical false positive by first identifying the subset of stellar blends that reproduce the precise shape of the light curve. Using the additional constraints from the measured color of the system, the absence of a secondary source in the high-resolution spectrum, and the absence of a secondary source in the adaptive optics imaging, we conclude that the planetary scenario is more than three orders of magnitude more likely than a blend. The blend scenario is independently disfavored by the achromaticity of the transit: we measure a transit depth with Spitzer at 4.5 μm of 547+113 – 110 ppm, consistent with the depth measured in the Kepler optical bandpass of 567 ± 6 ppm (corrected for stellar limb darkening). We determine a physical radius of the planet Kepler-19b of Rp = 2.209 ± 0.048 R ⊕; the uncertainty is dominated by uncertainty in the stellar parameters. From radial velocity observations of the star, we find an upper limit on the planet mass of 20.3 M ⊕, corresponding to a maximum density of 10.4 g cm–3. We report a significant sinusoidal deviation of the transit times from a predicted linear ephemeris, which we conclude is due to an additional perturbing body in the system. We cannot uniquely determine the orbital parameters of the perturber, as various dynamical mechanisms match the amplitude, period, and shape of the transit timing signal and satisfy the host star's radial velocity limits. However, the perturber in these mechanisms has a period 160 days and mass 6 M Jup, confirming its planetary nature as Kepler-19c. We place limits on the presence of transits of Kepler-19c in the available Kepler data.
    The Astrophysical Journal 12/2011; 743(2):200. · 6.73 Impact Factor
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    ABSTRACT: The detection and characterization of the first transiting super-Earth, CoRoT-7 b, has required an unprecedented effort in terms of telescope time and analysis. Although the star does display a radial velocity signal at the period of the planet, this has been difficult to disentangle from the intrinsic stellar variability, and pinning down the velocity amplitude has been very challenging. As a result, the precise value of the mass of the planet - and even the extent to which it can be considered to be confirmed - have been debated in the recent literature, with six mass measurements published so far based on the same spectroscopic observations, ranging from about 2 to 8 Earth masses. Here we report on an independent validation of the planet discovery, using one of the fundamental properties of a transit signal: its achromaticity. We observed four transits of CoRoT-7 b with Spitzer, in order to determine whether the depth of the transit signal in the near-infrared is consistent with that observed in the CoRoT bandpass, as expected for a planet. We detected the transit and found an average depth of 0.426 {\pm} 0.115 mmag at 4.5 {\mu}m, which is in good agreement with the depth of 0.350 {\pm} 0.011 mmag found by CoRoT. These observations place important constraints on the kinds of astrophysical false positives that could mimic the signal. Combining this with additional constraints reported earlier, we performed an exhaustive exploration of possible blends scenarios for CoRoT-7 b using the BLENDER technique. We are able to rule out the vast majority of false positives, and the remaining ones are found to be much less likely than a true transiting planet. We thus validate CoRoT-7 b as a bona-fide planet with a very high degree of confidence, independently of any radial-velocity information. Our Spitzer observations have additionally allowed us to significantly improve the ephemeris of the planet.
    The Astrophysical Journal 10/2011; 745(2012-1):A81. · 6.73 Impact Factor
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    ABSTRACT: We report the detection of three transiting planets around a Sun-like star, which we designate Kepler-18. The transit signals were detected in photometric data from the Kepler satellite, and were confirmed to arise from planets using a combination of large transit-timing variations (TTVs), radial velocity variations, Warm-Spitzer observations, and statistical analysis of false-positive probabilities. The Kepler-18 star has a mass of 0.97 M ☉, a radius of 1.1 R ☉, an effective temperature of 5345 K, and an iron abundance of [Fe/H] = +0.19. The planets have orbital periods of approximately 3.5, 7.6, and 14.9 days. The innermost planet "b" is a "super-Earth" with a mass of 6.9 ± 3.4 M ⊕, a radius of 2.00 ± 0.10 R ⊕, and a mean density of 4.9 ± 2.4 g cm3. The two outer planets "c" and "d" are both low-density Neptune-mass planets. Kepler-18c has a mass of 17.3 ± 1.9 M ⊕, a radius of 5.49 ± 0.26 R ⊕, and a mean density of 0.59 ± 0.07 g cm3, while Kepler-18d has a mass of 16.4 ± 1.4 M ⊕, a radius of 6.98 ± 0.33 R ⊕ and a mean density of 0.27 ± 0.03 g cm3. Kepler-18c and Kepler-18d have orbital periods near a 2:1 mean-motion resonance, leading to large and readily detected TTVs.
    The Astrophysical Journal Supplement Series 10/2011; 197(1):7. · 16.24 Impact Factor
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    ABSTRACT: The Kepler Mission has recently announced the discovery of Kepler-10 b, the smallest exoplanet discovered to date and the first rocky planet found by the spacecraft. A second, 45-day period transit-like signal present in the photometry from the first eight months of data could not be confirmed as being caused by a planet at the time of that announcement. Here we apply the light-curve modeling technique known as BLENDER to explore the possibility that the signal might be due to an astrophysical false positive (blend). To aid in this analysis we report the observation of two transits with the Spitzer Space Telescope at 4.5 {\mu}m. When combined they yield a transit depth of 344 \pm 85 ppm that is consistent with the depth in the Kepler passband (376 \pm 9 ppm, ignoring limb darkening), which rules out blends with an eclipsing binary of a significantly different color than the target. Using these observations along with other constraints from high resolution imaging and spectroscopy we are able to exclude the vast majority of possible false positives. We assess the likelihood of the remaining blends, and arrive conservatively at a false alarm rate of 1.6 \times 10-5 that is small enough to validate the candidate as a planet (designated Kepler-10 c) with a very high level of confidence. The radius of this object is measured to be Rp = 2.227+0.052 -0.057 Earth radii. Kepler-10 c represents another example (with Kepler-9 d and Kepler-11 g) of statistical "validation" of a transiting exoplanet, as opposed to the usual "confirmation" that can take place when the Doppler signal is detected or transit timing variations are measured. It is anticipated that many of Kepler's smaller candidates will receive a similar treatment since dynamical confirmation may be difficult or impractical with the sensitivity of current instrumentation.
    The Astrophysical Journal Supplement Series 05/2011; 197(1). · 16.24 Impact Factor
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    ABSTRACT: Confirmation of candidate transiting planets is usually achieved by spectroscopic means, with the detection of the reflex motion of the star, a line bisector analysis, or observation of the Rossiter-McLaughlin effect. Many of the most interesting candidate transiting planets identified by the Kepler Mission cannot be confirmed in this way, including Earth- or super-Earth-size planets in the habitable zone of their parent stars. The planetary masses are so small, and/or the orbital periods so long, that their Doppler signal is undetectable with current instrumentation. Additionally, the stars may be too faint, too chromospherically active, or rotating too rapidly for precise radial-velocity measurements. Transit timing variations in multiple systems may also be so small as to be unmeasurable in many cases. Lacking these methods of dynamical confirmation, the Kepler team has developed ways of "validating" candidates by modeling the photometry to place constraints on the wide range of false positives ("blends") that can mimic the transit light curves, including background eclipsing binaries and hierarchical triple systems. This presentation will describe this modeling, and how it is combined with complementary constraints from follow-up observations and centroid motion analysis to estimate the frequency of blends, and ultimately the probability that a candidate is a bona-fide planet. Funding for this Discovery mission is provided by NASA's Science Mission Directorate.

Publication Stats

57 Citations
280.77 Total Impact Points

Institutions

  • 2014
    • University of Copenhagen
      • Center for Star and Planet Formation
      København, Capital Region, Denmark
  • 2011–2013
    • California Institute of Technology
      • Jet Propulsion Laboratory
      Pasadena, California, United States
    • Yale University
      • Department of Astronomy
      New Haven, Connecticut, United States