Sensitivity Analyses of Exoplanet Occurrence Rates from Kepler and Gaia
Megan Shabram, Natalie Batalha, Susan E. Thompson, Danley C. Hsu, Eric B. Ford, Jessie L. Christiansen, Daniel Huber, Travis Berger, Joseph Catanzarite, Benjami… 展开作者
Megan Shabram, Natalie Batalha, Susan E. Thompson, Danley C. Hsu, Eric B. Ford, Jessie L. Christiansen, Daniel Huber, Travis Berger, Joseph Catanzarite, Benjamin E. Nelson, Steve Bryson, Ruslan Belikov, Chris Burke, Doug Caldwell
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16 pages, 3 figures, published in the Astrophysical Journal
We infer the number of planets-per-star as a function of orbital period and planet size using $Kepler$ archival data products with updated stellar properties from the $Gaia$ Data Release 2. Using hierarchical Bayesian modeling and Hamiltonian Monte Carlo, we incorporate planet radius uncertainties into an inhomogeneous Poisson point process model. We demonstrate that this model captures the general features of the outcome of the planet formation and evolution around GK stars, and provides an infrastructure to use the $Kepler$ results to constrain analytic planet distribution models. We report an increased mean and variance in the marginal posterior distributions for the number of planets per $GK$ star when including planet radius measurement uncertainties. We estimate the number of planets-per-$GK$ star between 0.75 and 2.5 $R_{\oplus}$ and 50 to 300 day orbital periods to have a $68\%$ credible interval of $0.49$ to $0.77$ and a posterior mean of $0.63$. This posterior has a smaller mean and a larger variance than the occurrence rate calculated in this work and in Burke et al. (2015) for the same parameter space using the $Q1-Q16$ (previous $Kepler$ planet candidate and stellar catalog). We attribute the smaller mean to many of the instrumental false positives at longer orbital periods being removed from the $DR25$ catalog. We find that the accuracy and precision of our hierarchical Bayesian model posterior distributions are less sensitive to the total number of planets in the sample, and more so on the characteristics of the catalog completeness and reliability and the span of the planet parameter space.
The so-called "global polytropic model" is applied to the numerical study of the exoplanet systems HD 10180, Kepler-32, Kepler-33, Kepler-102, and Kepler-186. We compare computed distances of planets from their host stars with corresponding observations and discuss some further orbit predictions made by the model.
In the framework of the so-called "global polytropic model", we assume hydrostatic equilibrium for a planetary system, and solve the resulting Lane--Emden differential equation in the complex plane. We thus obtain polytropic spherical shells defined by succesive roots of the real part $\mathrm{Re}(θ)$ of the Lane-Emden function $θ$. These shells seem to provide hosting orbits for the planets of the system(s) under consideration. In the present investigation, we study within this framework the exoplanet systems 55 Cnc, $\upsilon$ And, Kepler-11, Kepler-20, and Kepler-90.
Several attempts have been made in the past to assess the expected number of exoplanetary transits that the Gaia space mission will detect. In this Letter we use the updated design of Gaia and its expected performance, and apply recent empirical statistical procedures to provide a new assessment. Depending on the extent of the follow-up effort that will be devoted, we expect Gaia to detect a few hundreds to a few thousands transiting exoplanets.
The wealth of information in the Gaia catalogue of exoplanets will constitute a fundamental contribution to several hot topics of the astrophysics of planetary systems. I briefly review the potential impact of Gaia micro-arsec astrometry in several areas of exoplanet science, discuss what key follow-up observations might be required as a complement to Gaia data, and shed some light on the role of next generation astrometric facilities in the arena of planetary systems.
According to the so-called "global polytropic model", hydrostatic equilibrium for a planetary system leads to the Lane-Emden differential equation. Solving this equation in the complex plane, we obtain polytropic spherical shells defined by succesive roots of the real part $\mathrm{Re}(θ)$ of the Lane-Emden function $θ$. Such shells provide hosting orbits for the members of a planetary system. Within the framework of the global polytropic model, we study the exoplanet systems HD 40307, $μ$ Ara, Kepler-26, Kepler-62, and Kepler-275. We give emphasis on comparing our results with observations, a…
Numerous telescopes and techniques have been used to find and study extrasolar planets, but none has been more successful than NASA's Kepler Space Telescope. Kepler has discovered the majority of known exoplanets, the smallest planets to orbit normal stars, and the worlds most likely to be similar to our home planet. Most importantly, Kepler has provided our first look at typical characteristics of planets and planetary systems for planets with sizes as small as and orbits as large as those of the Earth.
We use the Robo-AO survey of Kepler planetary candidate host stars, the largest adaptive optics survey yet performed, to measure the recovery rate of close stellar binaries in Gaia DR2. We find that Gaia recovers binaries down to 1" at magnitude contrasts as large as 6; closer systems are not resolved, regardless of secondary brightness. Gaia DR2 binary detection does not have a strong dependence on the orientation of the stellar pairs. We find 177 nearby stars to Kepler planetary candidate host stars in Gaia DR2 that were not detected in the Robo-AO survey, almost all of which are faint (G>20…
A unique short-period Mercury-size Kepler exoplanet candidate KIC012557548b has been discovered recently by Rappaport et al. (2012). This object is a transiting disintegrating exoplanet with a circum-planetary material - comet-like tail. Close-in exoplanets, like KIC012557548b, are subjected to the greatest planet-star interactions. This interaction may have various forms. In certain cases it may cause formation of the comet-like tail. Strong interaction with the host star, and/or presence of an additional planet may lead to variations in the orbital period of the planet. Our main aim is to se…
The presence of mean-motion resonances (MMRs) in exoplanetary systems is a new exciting field of celestial mechanics which motivates us to consider this work to study the dynamical behaviour of exoplanetary systems by time evolution of the orbital elements of the planets. Mainly, we study the influence of planetary perturbations on semimajor axis and eccentricity. We identify $(r+1):r$ MMR terms in the expression of disturbing function and obtain the perturbations from the truncated disturbing function. Using the expansion of the disturbing function of three-body problem and an analytical appr…
The era of high-precision astrometry has dawned upon us. The potential of Gaia $μ$as-level precision in positional measurements is about to be unleashed in the field of extrasolar planetary systems. The Gaia data hold the promise for much improved global characterization of planetary systems around stars of all types, ages, and chemical composition, particularly when synergistically combined with other indirect and direct planet detection and characterization programs.
We observed Kepler-421 during the anticipated third transit of the snow-line exoplanet Kepler-421b in order to constrain the existence and extent of transit timing variations (TTVs). Previously, the Kepler Spacecraft only observed two transits of Kepler-421b leaving the planet's transit ephemeris unconstrained. Our visible light, time-series observations from the 4.3-meter Discovery Channel Telescope were designed to capture pre-transit baseline and the partial transit of Kepler-421b barring significant TTVs. We use the light curves to assess the probabilities of various transit models using b…
The search for extrasolar planets has developed rapidly and, today, more than 1700 planets have been found orbiting stars. Thanks to Gaia, we will collect high-accuracy astrometric orbits of thousands of new low-mass celestial objects, such as extra-solar planets and brown dwarfs. These measurements in combination with spectroscopy and with present day and future extrasolar planet search programs (like HARPS, ESPRESSO) will have a crucial contribution to several aspects of planetary astrophysics (formation theories, dynamical evolution, etc.). Moreover, Gaia will have a strong contribution on …
We acquired observations of a partial transit of Kepler-167e, a Jupiter-analog exoplanet on a 1,071-day orbit, well beyond its water ice line, with the Spitzer Space Telescope. The timing of the Spitzer transit is consistent with the ephemeris measured from the two transits observed previously by the Kepler Space Telescope. The Spitzer observation rules out the existence of transit timing variations (TTVs) of order hours to days that are known to exist for other long-period exoplanets. Such TTVs render transit follow-up efforts intractable due to the substantial observing time required and the…
We initiated the Robo-AO Kepler Planetary Candidate Survey in 2012 to observe each Kepler exoplanet candidate host star with high-angular-resolution visible-light laser-adaptive-optics imaging. Our goal is to find nearby stars lying in Kepler's photometric apertures that are responsible for the relatively high probability of false-positive exoplanet detections and that cause underestimates of the size of transit radii. Our comprehensive survey will also shed light on the effects of stellar multiplicity on exoplanet properties and will identify rare exoplanetary architectures. In this second pa…
In a previous paper we presented the Directed Follow-Up (DFU) approach, which we suggested can be used to efficiently augment low-cadence photometric surveys in a way that will optimize the chances to detect transiting exoplanets. In this paper we present preliminary tests of applying the DFU approach to the future ESA space mission Gaia. We demonstrate the strategy application to Gaia photometry through a few simulated cases of known transiting planets, using Gaia expected performance and current design. We show that despite the low cadence observations DFU, when tailored for Gaia's scanning …
We analyze a sample of multiple-exoplanet systems which contain at least 3 transiting planets detected by the Kepler mission ("Kepler multiples"). We use a generalized Titius-Bode relation to predict the periods of 228 additional planets in 151 of these Kepler multiples. These Titius-Bode-based predictions suggest that there are, on average, ~2 planets in the habitable zone of each star. We estimate the inclination of the invariable plane for each system and prioritize our planet predictions by their geometric probability to transit. We highlight a short list of 77 predicted planets in 40 syst…
The eccentricity distribution of exoplanets is known from radial velocity surveys to be divergent from circular orbits beyond 0.1 AU. This is particularly the case for large planets where the radial velocity technique is most sensitive. The eccentricity of planetary orbits can have a large effect on the transit probability and subsequently the planet yield of transit surveys. The Kepler mission is the first transit survey that probes deep enough into period-space to allow this effect to be seen via the variation in transit durations. We use the Kepler planet candidates to show that the eccentr…
Photometric phase curves provide an important window onto exoplanetary atmospheres and potentially even their surfaces. With similar amplitudes to occultations but far longer baselines, they have a higher sensitivity to planetary photons at the expense of a more challenging data reduction in terms of long-term stability. In this work, we introduce a novel non-parametric algorithm dubbed "phasma" to produce clean, robust exoplanet phase curves and apply it to 115 Neptunian and 50 Terran exoplanets observed by Kepler. We stack the signals to further improve signal-to-noise, and measure an averag…
Kepler has detected numerous exoplanet transits by precise measurements of stellar light in a single visible-wavelength band. In addition to detection, the precise photometry provides phase curves of exoplanets, which can be used to study the dynamic processes on these planets. However, the interpretation of these observations can be complicated by the fact that visible-wavelength phase curves can represent both thermal emission and scattering from the planets. Here we present a semi-analytical model framework that can be applied to study Kepler and future visible-wavelength phase curve observ…
Observations of exoplanetary systems provide clues about the intrinsic distribution of planetary systems, their architectures, and how they formed. We develop a forward modelling framework for generating populations of planetary systems and "observed" catalogues by simulating the Kepler detection pipeline (SysSim). We compare our simulated catalogues to the Kepler DR25 catalogue of planet candidates, updated to include revised stellar radii from Gaia DR2. We constrain our model based on the observed 1D marginal distributions of orbital periods, period ratios, transit depths, transit depth rati…
Exomoons represent a crucial missing puzzle piece in our efforts to understand extrasolar planetary systems. To address this deficiency, we here describe an exomoon survey of 70 cool, giant transiting exoplanet candidates found by Kepler. We identify only one which exhibits a moon-like signal that passes a battery of vetting tests: Kepler-1708 b. We show that Kepler-1708 b is a statistically validated Jupiter-sized planet orbiting a Sun-like quiescent star at ~1.6AU. The signal of the exomoon candidate, Kepler-1708 b-i, is a 4.8-sigma effect and is persistent across different instrumental detr…
We embark on a detailed study of the lightcurves of Keplers most Earth-like exoplanet host stars using the full length of Kepler data. We derive rotation periods, photometric activity indices, flaring energies, mass loss rates, gyrochronological ages, X-ray luminosities and consider implications for the planetary magnetospheres and habitability. Furthermore, we present the detection of superflares in the lightcurve of Kepler-438, the exoplanet with the highest Earth Similarity Index to date. Kepler-438b orbits at a distance of 0.166AU to its host star, and hence may be susceptible to atmospher…
We provide a revised assessment of the number of exoplanets that should be discovered by Gaia astrometry, extending previous studies to a broader range of spectral types, distances, and magnitudes. Our assessment is based on a large representative sample of host stars from the TRILEGAL Galaxy population synthesis model, recent estimates of the exoplanet frequency distributions as a function of stellar type, and detailed simulation of the Gaia observations using the updated instrument performance and scanning law. We use two approaches to estimate detectable planetary systems: one based on the …
In its all-sky survey, Gaia will monitor astrometrically hundreds of thousands of main-sequence stars within $\approx200$ pc, looking for the presence of giant planetary companions within a few AUs from their host stars. Indeed, Gaia observations will have great impact is the astrophysics of planetary systems (e.g., Casertano et al. 2008), in particular when seen as a complement to other techniques for planet detection and characterization (e.g., Sozzetti 2011). In this paper, I briefly address some of the relevant technical issues associated with the precise and accurate determination of astr…
Accurate stellar properties are crucial for determining exoplanet characteristics. Gaia DR2 presents revised distances, luminosities, and radii for 1.6 billion stars. Here, we report the calculation of revised radii and densities for 320 exoplanets using this data and present updated calculations of the incident flux received by 690 known exoplanets. This allows the likelihood that those planets orbit in the habitable zone of their host stars to be reassessed. As a result of this analysis, three planets can be added to the catalogue of potentially habitable worlds: HIP~67537~b, HD~148156~b, an…
Despite the severe bias of the transit method of exoplanet discovery toward short orbital periods, a modest sample of transiting exoplanets with orbital periods greater than 100 days is known. Long-term radial velocity (RV) surveys are pivotal to confirming these signals and generating a set of planetary masses and densities for planets receiving moderate to low irradiation from their host stars. Here, we conduct RV observations of Kepler-1514 from the Keck I telescope using the High Resolution Echelle Spectrometer. From these data, we measure the mass of the statistically validated giant ($1.…
The prime Kepler mission detected 34,032 transit-like signals, out of which 8,054 were identified as likely due to astrophysical planet transits or eclipsing binaries. We manually examined 306 of the remaining 25,978 detections, and found six plausible transiting or eclipsing objects, five of which are plausible planet candidates (PCs), and one stellar companion. One of our new PCs is a possible new second planet in the KOI 4302 system. Another new PC is a possible new planet around the KOI 4246, and when combined with a different possible planet rescued by the False Positive Working Group, we…
An analysis of the currently known exoplanets in the habitable zones (HZs) of their host stars is of interest in both the wake of the NASA Kepler mission and with prospects for expanding the known planet population through future ground- and space-based projects. In this paper we compare the empirical distributions of the properties of stellar systems with transiting planets to those with transiting HZ planets. This comparison includes two categories: confirmed/validated transiting planet systems, and Kepler planet and candidate planet systems. These two categories allow us to present quantita…
Simulation of the spin evolution of some selected exoplanets and inferences on their climate
Università di Padova（帕多瓦大学）；Università di Bari（巴里大学）；Istituto Nazionale di Fisica Nucleare（意大利国家核物理研究所）；Università del Salento（萨伦托大学）；Istituto Nazionale di Astrofisica（意大利国家天体物理研究所）
Results on the obliquity of exoplanet host stars -- the angle between the stellar spin axis and the planetary orbital axis -- provide important diagnostic information for theories describing planetary formation. Here we present the first application of asteroseismology to the problem of stellar obliquity determination in systems with transiting planets and Sun-like host stars. We consider two systems observed by the NASA Kepler Mission which have multiple transiting small (super-Earth sized) planets: the previously reported Kepler-50 and a new system, Kepler-65, whose planets we validate in th…
The measurement of an exoplanet's oblateness and obliquity provides insights into the planet's internal structure and formation history. Previous work using small differences in the shape of the transit light curve has been moderately successful, but was hampered by the small signal and extreme photometric precision required. The measurement of changes in transit depth, caused by the spin precession of an oblate planet, was proposed as an alternative method. Here, we present the first attempt to measure these changes. Using Kepler photometry, we examined the brown dwarf Kepler-39b and the warm…
High resolution imaging is an important tool for follow-up study of exoplanet candidates found via transit detection with the Kepler Mission. We discuss here HST imaging with the WFC3 of 23 stars that host particularly interesting Kepler planet candidates based on their small size and cool equilibrium temperature estimates. Results include detections, exclusion of background stars that could be a source of false positives for the transits, and detection of physically-associated companions in a number of cases providing dilution measures necessary for planet parameter refinement. For six KOIs, …
We infer dynamical masses in eight multi-planet systems using transit times measured from Kepler's complete dataset, including short-cadence data where available. Of the eighteen dynamical masses that we infer, ten pass multiple tests for robustness. These are in systems; Kepler-26 (KOI-250), Kepler-29 (KOI-738), Kepler-60 (KOI-2086), Kepler-105 (KOI-115), and Kepler-307 (KOI-1576). Kepler-105 c has a density consistent with an Earth-like composition. Strong TTV signals were detected from additional planets, but their inferred masses were sensitive to outliers or consistent solutions could not…
The true multiplicity distribution of transiting planet systems is obscured by strong observational biases, leading low-multiplicity systems to be overrepresented in the observed sample. Using the Kepler FGK planet hosts, we employ approximate Bayesian computation to infer the multiplicity distribution by comparing simulated catalogs to the observed one. After comparing a total of ten different multiplicity distributions, half of which were two-population models, to the observed data, we find that a single-population model following a Zipfian distribution is able to explain the Kepler data as …
The vast majority of the 4700 confirmed planets and planet candidates discovered by the Kepler mission were first found by the Kepler pipeline. In the pipeline, after a transit signal is found, all data points associated with those transits are removed, creating a "Swiss cheese"-like light curve full of holes, which is then used for subsequent transit searches. These holes could render an additional planet undetectable (or "lost"). We examine a sample of 114 stars with $3+$ confirmed planets to evaluate the effect of this "Swiss cheesing". A simulation determines that the probability that a tr…
Context: The space telescope Gaia is dedicated mainly to performing high-precision astrometry, but also spectroscopy and epoch photometry which can be used to study various types of photometric variability. One such variability type is exoplanetary transits. The photometric data accumulated so far have finally matured enough to allow the detection of some exoplanets. Aims: In order to fully exploit the scientific potential of Gaia, we search its photometric data for the signatures of exoplanetary transits. Methods: The search relies on a version of the Box-Least-Square (BLS) method, applied to…
We have used the {\it Spitzer Space Telescope} to observe two transiting planetary systems orbiting low mass stars discovered in the \Kepler \Ktwo mission. The system K2-3 (EPIC 201367065) hosts three planets while EPIC 202083828 (K2-26) hosts a single planet. Observations of all four objects in these two systems confirm and refine the orbital and physical parameters of the planets. The refined orbital information and more precise planet radii possible with \Spitzer will be critical for future observations of these and other \Ktwo targets. For K2-3b we find marginally significant evidence for …
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 three years of data, 100 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…
We announce confirmation of Kepler-418b, one of two proposed planets in this system. This is the first confirmation of an exoplanet based primarily on the transit color signature technique. We used the Kepler public data archive combined with multicolor photometry from the Gran Telescopio de Canarias and radial velocity follow-up using FIES at the Nordic Optical Telescope for confirmation. We report a confident detection of a transit color signature that can only be explained by a compact occulting body, entirely ruling out a contaminating eclipsing binary, a hierarchical triple, or a grazing …
Short-period exoplanets potentially lose envelope masses during their evolution because of atmospheric escape caused by the intense XUV radiation from their host stars. We develop a combined model of atmospheric mass loss calculation and thermal evolution calculation of a planet to simulate its evolution and explore the dependences on the formation history of the planet. Thermal atmospheric escape as well as the Roche-lobe overflow contributes to mass loss. The maximum initial planetary model mass depends primarily on the assumed evolution model of the stellar XUV luminosity. We adapt the mode…
Three transiting exoplanet candidate stars were discovered in a ground-based photometric survey prior to the launch of NASA's {\it Kepler} mission. {\it Kepler} observations of them were obtained during Quarter 1 of the {\it Kepler} mission. All three stars are faint by radial velocity follow-up standards, so we have examined these candidates with regard to eliminating false positives and providing high confidence exoplanet selection. We present a first attempt to exclude false positives for this set of faint stars without high resolution radial velocity analysis. This method of exoplanet conf…
In favourable conditions, the density of transiting planets in multiple systems can be determined from photometry data alone. Dynamical information can be extracted from light curves, providing modelling is done self-consistently, i.e. using a photodynamical model, which simulates the individual photometric observations instead of the more generally used transit times. We apply this methodology to the Kepler-138 planetary system. The derived planetary bulk densities are a factor of 2 more precise than previous determinations, and we find a discrepancy in the stellar bulk density with respect t…
The Robo-AO \textit{Kepler} Planetary Candidate Survey is observing every \textit{Kepler} planet candidate host star with laser adaptive optics imaging to search for blended nearby stars, which may be physically associated companions and/or responsible for transit false positives. We present in this paper the results of our search for stars nearby 1629 \textit{Kepler} planet candidate hosts. With survey sensitivity to objects as close as $\sim$0.15" and magnitude differences $Δ$m$\le$6, we find 223 stars in the vicinity of 206 target KOIs; 209 of these nearby stars have not previously been ima…
This paper introduces a new method of inferring the intrinsic exoplanet population from Kepler data, based on the assumption that the frequency of exoplanets can be represented by a smooth function of planet radius and period. The method is applied to the two most recent data releases from the Kepler project, q1-16 and q1-17, over the range of periods 0.5 to 512 days, and radii 0.5 to 16 Earth radii. Both of these releases have known biases, with the first believed to contain excess false positives, and the second excess false negatives, so any analysis of them should be viewed with caution. W…
We present new visible and infrared observations of the hot Jupiter Kepler-7b to determine its atmospheric properties. Our analysis allows us to 1) refine Kepler-7b's relatively large geometric albedo of Ag=0.35+-0.02, 2) place upper limits on Kepler-7b thermal emission that remains undetected in both Spitzer bandpasses and 3) report a westward shift in the Kepler optical phase curve. We argue that Kepler-7b's visible flux cannot be due to thermal emission or Rayleigh scattering from H2 molecules. We therefore conclude that high altitude, optically reflective clouds located west from the subst…
A Planetary Illusion's Funeral: Non-detection of a Gaia DR3 Exoplanet Candidate, and the Role of Intermediate-precision Radial Velocities in Gaia Exoplanet Follow-up
Centre for Astrophysics, University of Southern Queensland（南昆士兰大学天体物理中心）；Max Planck Institute for Astronomy（马克斯·普朗克天文学研究所）；Center for Astrophysics, Harvard & Smithsonian（哈佛-史密森尼天体物理中心）
NASA's Kepler Mission revolutionized exoplanet science in the early part of the 2010's. Looking back from the perspective of the end of that decade, Kepler appears to have burst upon the scene ready for battle, like Athena springing forth, fully formed, from the head of Zeus. The story was not so simple. Kepler's first major exoplanet discoveries were not announced until more than a year had passed since the spacecraft started collecting scientific data, and by that time many exoplanet scientists not working on the project had become frustrated with the lack of results coming from the Kepler p…
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 as…
Extrasolar planets that pass in front of their host star (transit) cause a temporary decrease in the apparent brightness of the star once per orbit, providing a direct measure of the planet's size and orbital period. In some systems with multiple transiting planets, the times of the transits are measurably affected by the gravitational interactions between neighbouring planets. In favorable cases, the departures from Keplerian orbits implied by the observed transit times permit planetary masses to be measured, which is key to determining bulk densities. Characterizing rocky planets is particul…
We determined new linear ephemerides of transiting exoplanets using long-cadence de-trended data from quarters Q1 to Q17 of Kepler mission. We analysed TTV diagrams of 2098 extrasolar planets. The TTVs of 121 objects were excluded (because of insufficient data-points, the influence of stellar activity, etc). Finally, new linear ephemerides of 1977 exoplanets from the Kepler archive are presented. The significant linear trend was observed on TTV diagrams of approximately 35% of studied exoplanets. Knowing correct linear ephemeris is principal for successful follow-up observations of transits. R…
New insights on stellar evolution and stellar interior physics are being made possible by asteroseismology, the study of stars by the observation of their natural, resonant oscillations. Asteroseismology is making significant contributions to our understanding of solar-type stars, in great part due to the exquisite data that have been made available by NASA's Kepler space telescope. Of particular interest is the synergy between asteroseismology and exoplanetary science. Herein I will review recent contributions from asteroseismology to the determination of fundamental properties of Kepler exop…
The radius-period distribution of exoplanets has been characterized by the \textit{Kepler} survey, and the empirical mass-radius relation by the subset of \textit{Kepler} planets with mass measurements. We combine the two in order to constrain the joint mass-radius-period distribution of \textit{Kepler} transiting planets. We employ hierarchical Bayesian modeling and mixture models to formulate four models with varying complexity and fit these models to the data. We find that the most complex models that treat planets with significant gaseous envelopes, evaporated core planets, and intrinsical…
Data from Kepler's first 136 days of operation are analyzed to determine the distribution of exoplanets with respect to radius, period, and host-star spectral type. The analysis is extrapolated to estimate the percentage of terrestrial, habitable-zone exoplanets. The Kepler census is assumed to be complete for bright stars (magnitude <14.0) having transiting planets >0.5 Earth radius and periods <42 days. It is also assumed that the size distribution of planets is independent of orbital period, and that there are no hidden biases in the data. Six significant statistical results are found: ther…
We present ground-based observations from the Discovery Channel Telescope (DCT) of three transits of Kepler-445c---a supposed super-Earth exoplanet with properties resembling GJ 1214b---and demonstrate that the transit depth is approximately 50 percent shallower than the depth previously inferred from Kepler Spacecraft data. The resulting decrease in planetary radius significantly alters the interpretation of the exoplanet's bulk composition. Despite the faintness of the M4 dwarf host star, our ground-based photometry clearly recovers each transit and achieves repeatable 1-sigma precision of a…
We characterize the occurrence rate of planets, ranging in size from 0.5-16 R$_\oplus$, orbiting FGK stars with orbital periods from 0.5-500 days. Our analysis is based on results from the "DR25" catalog of planet candidates produced by NASA's Kepler mission and stellar radii from Gaia "DR2". We incorporate additional Kepler data products to accurately characterize the efficiency of planets being recognized as a "threshold crossing events" (TCE) by Kepler's Transiting Planet Search pipeline and labeled as a planet candidate by the robovetter. Using a hierarchical Bayesian model, we derive plan…
