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Adaptive Optics Images of Kepler Objects of Interest
All transiting planets are at risk of contamination by blends withnearby, unresolved stars. Blends dilute the transit signal, causing theplanet to appear smaller than it really is, or produce a false-positivedetection when the target star is blended with eclipsing binary stars.This paper reports on high spatial-resolution adaptive optics images of90 Kepler planetary candidates. Companion stars are detected as close as0farcs1 from the target star. Images were taken in the near-infrared (Jand Ks bands) with ARIES on the MMT and PHARO on the Palomar Hale 200inch telescope. Most objects (60%) have at least one star within 6''separation and a magnitude difference of 9. Eighteen objects (20%) haveat least one companion within 2'' of the target star; six companions(7%) are closer than 0farcs5. Most of these companions were previouslyunknown, and the associated planetary candidates should receiveadditional scrutiny. Limits are placed on the presence of additionalcompanions for every system observed, which can be used to validateplanets statistically using the BLENDER method. Validation isparticularly critical for low-mass, potentially Earth-like worlds, whichare not detectable with current-generation radial velocity techniques.High-resolution images are thus a crucial component of any transitfollow-up program.Based on observations obtained at the MMT Observatory, a joint facilityof the Smithsonian Institution and the University of Arizona.
| Detection of Potential Transit Signals in the First Three Quarters of Kepler Mission Data
We present the results of a search for potential transit signals in thefirst three quarters of photometry data acquired by the Kepler mission.The targets of the search include 151,722 stars which were observed overthe full interval and an additional 19,132 stars which were observed foronly one or two quarters. From this set of targets we find a total of5392 detections which meet the Kepler detection criteria: those criteriaare periodicity of signal, an acceptable signal-to-noise ratio, and acomposition test which rejects spurious detections which containnon-physical combinations of events. The detected signals are dominatedby events with relatively low signal-to-noise ratio and by events withrelatively short periods. The distribution of estimated transit depthsappears to peak in the range between 40 and 100 parts per million, witha few detections down to fewer than 10 parts per million. The detectionsexhibit signal-to-noise ratios from 7.1σ, which is the lowercutoff for detections, to over 10,000σ, and periods ranging from0.5 days, which is the lower cutoff used in the procedure, to 109 days,which is the upper limit of achievable periods given the length of thedata set and the criteria used for detections. The detected signals arecompared to a set of known transit events in the Kepler field of viewwhich were derived by a different method using a longer data interval;the comparison shows that the current search correctly identified 88.1%of the known events. A tabulation of the detected transit signals,examples which illustrate the analysis and detection process, adiscussion of future plans and open, potentially fruitful, areas offurther research are included.
| Identifying non-resonant Kepler planetary systems
The Kepler mission has discovered a plethora of multiple transitingplanet candidate exosystems, many of which feature putative pairs ofplanets near mean motion resonance commensurabilities. Identifyingpotentially resonant systems could help guide future observations andenhance our understanding of planetary formation scenarios. We developand apply an algebraic method to determine which Kepler two-planetsystems cannot be in a first-fourth order resonance, given the current,publicly available data. This method identifies when any potentiallyresonant angle of a system must circulate. We identify and list 70near-resonant systems which cannot actually reside in resonance,assuming a widely used formulation for deriving planetary masses fromtheir observed radii and that these systems do not contain unseen bodiesthat affect the interactions of the observed planets. This workstrengthens the argument that a high fraction of exoplanetary systemsmay be near resonance but not actually in resonance.
| Architecture and Dynamics of Kepler's Candidate Multiple Transiting Planet Systems
About one-third of the ~1200 transiting planet candidates detected inthe first four months of Kepler data are members of multiple candidatesystems. There are 115 target stars with two candidate transitingplanets, 45 with three, 8 with four, and 1 each with five and six. Wecharacterize the dynamical properties of these candidate multi-planetsystems. The distribution of observed period ratios shows that the vastmajority of candidate pairs are neither in nor near low-ordermean-motion resonances. Nonetheless, there are small but statisticallysignificant excesses of candidate pairs both in resonance and spacedslightly too far apart to be in resonance, particularly near the 2:1resonance. We find that virtually all candidate systems are stable, astested by numerical integrations that assume a nominal mass-radiusrelationship. Several considerations strongly suggest that the vastmajority of these multi-candidate systems are true planetary systems.Using the observed multiplicity frequencies, we find that a singlepopulation of planetary systems that matches the higher multiplicitiesunderpredicts the number of singly transiting systems. We provideconstraints on the true multiplicity and mutual inclination distributionof the multi-candidate systems, revealing a population of systems withmultiple super-Earth-size and Neptune-size planets with low to moderatemutual inclinations.
| Transit Timing Observations from Kepler. I. Statistical Analysis of the First Four Months
The architectures of multiple planet systems can provide valuableconstraints on models of planet formation, including orbital migration,and excitation of orbital eccentricities and inclinations. NASA's Keplermission has identified 1235 transiting planet candidates. The method oftransit timing variations (TTVs) has already confirmed seven planets intwo planetary systems. We perform a transit timing analysis of theKepler planet candidates. We find that at least ~11% of planetcandidates currently suitable for TTV analysis show evidence suggestiveof TTVs, representing at least ~65 TTV candidates. In all cases, thetime span of observations must increase for TTVs to provide strongconstraints on planet masses and/or orbits, as expected based on N-bodyintegrations of multiple transiting planet candidate systems (assumingcircular and coplanar orbits). We find the fraction of planet candidatesshowing TTVs in this data set does not vary significantly with thenumber of transiting planet candidates per star, suggesting significantmutual inclinations and that many stars with a single transiting planetshould host additional non-transiting planets. We anticipate that Keplercould confirm (or reject) at least ~12 systems with multiple transitingplanet candidates via TTVs. Thus, TTVs will provide a powerful tool forconfirming transiting planets and characterizing the orbital dynamics oflow-mass planets. If Kepler observations were extended to at least sevenyears, then TTVs would provide much more precise constraints on thedynamics of systems with multiple transiting planets and would becomesensitive to planets with orbital periods extending into the habitablezone of solar-type stars.
| On the Low False Positive Probabilities of Kepler Planet Candidates
We present a framework to conservatively estimate the probability thatany particular planet-like transit signal observed by the Kepler missionis in fact a planet, prior to any ground-based follow-up efforts. We useMonte Carlo methods based on stellar population synthesis and Galacticstructure models, and report false positive probabilities (FPPs) forevery Kepler Object of Interest, assuming a 20% intrinsic occurrencerate of close-in planets in the radius range 0.5 R ⊕< Rp < 20 R ⊕. Nearly 90% of the 1235candidates have FPP <10%, and over half have FPP <5%. Thisprobability varies with the magnitude and Galactic latitude of thetarget star, and with the depth of the transit signal—deepersignals generally have higher FPPs than shallower signals. We establishthat a single deep high-resolution image will be an effective follow-uptool for the shallowest (Earth-sized) transits, providing the quickestroute toward probabilistically validating the smallest candidates bypotentially decreasing the FPP of an Earth-sized transit around a faintstar from >10% to <1%. Since Kepler has detected many moreplanetary signals than can be positively confirmed with ground-basedfollow-up efforts in the near term, these calculations will be crucialto using the ensemble of Kepler data to determine populationcharacteristics of planetary systems. We also describe how our analysiscomplements the Kepler team's more detailed BLENDER false positiveanalysis for planet validation.
| Characteristics of Planetary Candidates Observed by Kepler. II. Analysis of the First Four Months of Data
On 2011 February 1 the Kepler mission released data for 156,453 starsobserved from the beginning of the science observations on 2009 May 2through September 16. There are 1235 planetary candidates withtransit-like signatures detected in this period. These are associatedwith 997 host stars. Distributions of the characteristics of theplanetary candidates are separated into five class sizes: 68 candidatesof approximately Earth-size (R p < 1.25 R?), 288 super-Earth-size (1.25 R ?<= R p < 2 R ?), 662 Neptune-size (2 R? <= R p < 6 R ?),165 Jupiter-size (6 R ? <= R p < 15 R?), and 19 up to twice the size of Jupiter (15 R? <= R p < 22 R ?).In the temperature range appropriate for the habitable zone, 54candidates are found with sizes ranging from Earth-size to larger thanthat of Jupiter. Six are less than twice the size of the Earth. Over 74%of the planetary candidates are smaller than Neptune. The observednumber versus size distribution of planetary candidates increases to apeak at two to three times the Earth-size and then declines inverselyproportional to the area of the candidate. Our current best estimates ofthe intrinsic frequencies of planetary candidates, after correcting forgeometric and sensitivity biases, are 5% for Earth-size candidates, 8%for super-Earth-size candidates, 18% for Neptune-size candidates, 2% forJupiter-size candidates, and 0.1% for very large candidates; a total of0.34 candidates per star. Multi-candidate, transiting systems arefrequent; 17% of the host stars have multi-candidate systems, and 34% ofall the candidates are part of multi-candidate systems.
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Datos observacionales y astrométricos
| Constelación: | Lira |
| Ascensión Recta: | 18h45m55.91s |
| Declinación: | +47°12'29.2" |
| Magnitud Aparente: | 12.081 |
| Movimiento Propio en Ascensión Recta: | 0 |
| Movimiento Propio en Declinación: | 0 |
| B-T magnitude: | 12.683 |
| V-T magnitude: | 12.131 |
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