- ID:
- ivo://CDS.VizieR/J/AJ/153/71
- Title:
- Kepler follow-up observation program. I. Imaging
- Short Name:
- J/AJ/153/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from high-resolution, optical to near-IR imaging of host stars of Kepler Objects of Interest (KOIs), identified in the original Kepler field. Part of the data were obtained under the Kepler imaging follow-up observation program over six years (2009-2015). Almost 90% of stars that are hosts to planet candidates or confirmed planets were observed. We combine measurements of companions to KOI host stars from different bands to create a comprehensive catalog of projected separations, position angles, and magnitude differences for all detected companion stars (some of which may not be bound). Our compilation includes 2297 companions around 1903 primary stars. From high-resolution imaging, we find that ~10% (~30%) of the observed stars have at least one companion detected within 1'' (4''). The true fraction of systems with close (<~4'') companions is larger than the observed one due to the limited sensitivities of the imaging data. We derive correction factors for planet radii caused by the dilution of the transit depth: assuming that planets orbit the primary stars or the brightest companion stars, the average correction factors are 1.06 and 3.09, respectively. The true effect of transit dilution lies in between these two cases and varies with each system. Applying these factors to planet radii decreases the number of KOI planets with radii smaller than 2R_{Earth}_ by ~2%-23% and thus affects planet occurrence rates. This effect will also be important for the yield of small planets from future transit missions such as TESS.
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- ID:
- ivo://CDS.VizieR/J/ApJ/861/149
- Title:
- Kepler Follow-up Observation Program. II. Spectro.
- Short Name:
- J/ApJ/861/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from spectroscopic follow-up observations of stars identified in the Kepler field and carried out by teams of the Kepler Follow-up Observation Program. Two samples of stars were observed over 6yr (2009-2015): 614 standard stars (divided into "platinum" and "gold" categories) selected based on their asteroseismic detections and 2667 host stars of Kepler Objects of Interest (KOIs), most of them planet candidates. Four data analysis pipelines were used to derive stellar parameters for the observed stars. We compare the Teff, log(g), and [Fe/H] values derived for the same stars by different pipelines; from the average of the standard deviations of the differences in these parameter values, we derive error floors of ~100K, 0.2dex, and 0.1dex for Teff, log(g), and [Fe/H], respectively. Noticeable disagreements are seen mostly at the largest and smallest parameter values (e.g., in the giant star regime). Most of the log(g) values derived from spectra for the platinum stars agree on average within 0.025dex (but with a spread of 0.1-0.2dex) with the asteroseismic log(g) values. Compared to the Kepler Input Catalog (KIC), the spectroscopically derived stellar parameters agree within the uncertainties of the KIC but are more precise and thus an important contribution toward deriving more reliable planetary radii.
- ID:
- ivo://CDS.VizieR/J/ApJ/829/34
- Title:
- Kepler heartbeat star radial velocities
- Short Name:
- J/ApJ/829/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Heartbeat stars (HB stars) are a class of eccentric binary stars with close periastron passages. The characteristic photometric HB signal evident in their light curves is produced by a combination of tidal distortion, heating, and Doppler boosting near orbital periastron. Many HB stars continue to oscillate after periastron and along the entire orbit, indicative of the tidal excitation of oscillation modes within one or both stars. These systems are among the most eccentric binaries known, and they constitute astrophysical laboratories for the study of tidal effects. We have undertaken a radial velocity (RV) monitoring campaign of Kepler HB stars in order to measure their orbits. We present our first results here, including a sample of 22 Kepler HB systems, where for 19 of them we obtained the Keplerian orbit and for 3 other systems we did not detect a statistically significant RV variability. Results presented here are based on 218 spectra obtained with the Keck/HIRES spectrograph during the 2015 Kepler observing season, and they have allowed us to obtain the largest sample of HB stars with orbits measured using a single instrument, which roughly doubles the number of HB stars with an RV measured orbit. The 19 systems measured here have orbital periods from 7 to 90 days and eccentricities from 0.2 to 0.9. We show that HB stars draw the upper envelope of the eccentricity-period distribution. Therefore, HB stars likely represent a population of stars currently undergoing high eccentricity migration via tidal orbital circularization, and they will allow for new tests of high eccentricity migration theories.
- ID:
- ivo://CDS.VizieR/J/MNRAS/457/2877
- Title:
- Kepler M dwarf stars revised properties
- Short Name:
- J/MNRAS/457/2877
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We classified the reddest (r-J>2.2) stars observed by the NASA Kepler mission into main-sequence dwarf or evolved giant stars and determined the properties of 4216 M dwarfs based on a comparison of available photometry with that of nearby calibrator stars, as well as available proper motions and spectra. We revised the properties of candidate transiting planets using the stellar parameters, high-resolution imaging to identify companion stars, and, in the case of binaries, fitting light curves to identify the likely planet host. In 49 of 54 systems, we validated the primary as the host star. We inferred the intrinsic distribution of M dwarf planets using the method of iterative Monte Carlo simulation. We compared several models of planet orbital geometry and clustering and found that one where planets are exponentially distributed and almost precisely coplanar best describes the distribution of multiplanet systems. We determined that Kepler M dwarfs host an average of 2.2+/-0.3 planets with radii of 1-4R_{Earth}_ and orbital periods of 1.5-180d. The radius distribution peaks at ~1.2R_{Earth}_ and is essentially zero at 4R_{Earth}_, although we identify three giant planet candidates other than the previously confirmed Kepler-45b. There is suggestive but not significant evidence that the radius distribution varies with orbital period. The distribution with logarithmic orbital period is flat except for a decline for orbits less than a few days. 12 candidate planets, including two Jupiter-size objects, experience an irradiance below the threshold level for a runaway greenhouse on an Earth-like planet and are thus in a 'habitable zone'.
- ID:
- ivo://CDS.VizieR/J/ApJ/774/L12
- Title:
- Kepler multiplanet systems analysis (Q1-Q8)
- Short Name:
- J/ApJ/774/L12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Many Kepler multiplanet systems have planet pairs near low-order, mean-motion resonances. In addition, many Kepler multiplanet systems have planets with orbital periods less than a few days. With the exception of Kepler-42, however, there are no examples of systems with both short orbital periods and nearby companion planets while our statistical analysis predicts ~17 such pairs. For orbital periods of the inner planet that are less than three days, the minimum period ratio of adjacent planet pairs follows the rough constraint P=P_2_/P_1_>~2.3(P_1_/day)^-2/3^ (equation (1)). This absence is not due to a lack of planets with short orbital periods. We also show a statistically significant excess of small, single-candidate systems with orbital periods below three days over the number of multiple candidate systems with similar periods--perhaps a small-planet counterpart to the hot Jupiters.
- ID:
- ivo://CDS.VizieR/J/ApJ/763/41
- Title:
- Kepler multiple-candidate systems radii
- Short Name:
- J/ApJ/763/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the relative sizes of planets within the multiple-candidate systems discovered with the Kepler mission (Burke+, 2014, J/ApJS/210/29). We have compared the size of each planet to the size of every other planet within a given planetary system after correcting the sample for detection and geometric biases. We find that for planet pairs for which one or both objects are approximately Neptune-sized or larger, the larger planet is most often the planet with the longer period. No such size-location correlation is seen for pairs of planets when both planets are smaller than Neptune. Specifically, if at least one planet in a planet pair has a radius of >~3R_{oplus}_, 68%+/-6% of the planet pairs have the inner planet smaller than the outer planet, while no preferred sequential ordering of the planets is observed if both planets in a pair are smaller than <~3R_{oplus}_.
- ID:
- ivo://CDS.VizieR/J/ApJ/813/130
- Title:
- Kepler multiple transiting planet systems
- Short Name:
- J/ApJ/813/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kepler mission provides a wealth of multiple transiting planet systems (MTPSs). The formation and evolution of multi-planet systems are likely to be influenced by companion stars given the abundance of multiple stellar systems. We study the influence of stellar companions by measuring the stellar multiplicity rate of MTPSs. We select 138 bright (K_P_<13.5) Kepler MTPSs and search for stellar companions with adaptive optics (AO) imaging data and archival radial velocity data. We obtain new AO images for 73 MTPSs. Other MTPSs in the sample have archival AO imaging data from the Kepler Community Follow-up Observation Program. From these imaging data, we detect 42 stellar companions around 35 host stars. For stellar separation 1 AU<a<100 AU, the stellar multiplicity rate is 5.2+/-5.0% for MTPSs, which is 2.8{sigma} lower than 21.1+/-2.8% for the control sample, i.e., the field stars in the solar neighborhood. We identify two origins for the deficit of stellar companions within 100 AU of MTPSs: (1) a suppressive planet formation and (2) the disruption of orbital coplanarity due to stellar companions. To distinguish between the two origins, we compare the stellar multiplicity rates of MTPSs and single transiting planet systems (STPSs). However, current data are not sufficient for this purpose. For 100 AU<a<2000 AU, the stellar multiplicity rates are comparable for MTPSs (8.0+/-4.0%), STPSs (6.4+/-5.8%), and the control sample (12.5+/-2.8%).
- ID:
- ivo://CDS.VizieR/J/ApJ/728/117
- Title:
- Kepler planetary candidates. I.
- Short Name:
- J/ApJ/728/117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the spring of 2009, the Kepler Mission commenced high-precision photometry on nearly 156000 stars to determine the frequency and characteristics of small exoplanets, conduct a guest observer program, and obtain asteroseismic data on a wide variety of stars. On 2010 June 15, the Kepler Mission released most of the data from the first quarter of observations. At the time of this data release, 705 stars from this first data set have exoplanet candidates with sizes from as small as that of Earth to larger than that of Jupiter. Here we give the identity and characteristics of 305 released stars with planetary candidates. Data for the remaining 400 stars with planetary candidates will be released in 2011 February. More than half the candidates on the released list have radii less than half that of Jupiter. Five candidates are present in and near the habitable zone; two near super-Earth size, and three bracketing the size of Jupiter. The released stars also include five possible multi-planet systems. One of these has two Neptune-size (2.3 and 2.5 Earth radius) candidates with near-resonant periods.
- ID:
- ivo://CDS.VizieR/J/ApJ/736/19
- Title:
- Kepler planetary candidates. II.
- Short Name:
- J/ApJ/736/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On 2011 February 1 the Kepler mission released data for 156453 stars observed from the beginning of the science observations on 2009 May 2 through September 16. There are 1235 planetary candidates with transit-like signatures detected in this period. These are associated with 997 host stars. Distributions of the characteristics of the planetary candidates are separated into five class sizes: 68 candidates of approximately Earth-size (R_p_<1.25R_{earth}_), 288 super-Earth-size (1.25R_{earth}_<=R_p_<2R_{earth}_), 662 Neptune-size (2R_{earth}_<=R_p_<6R_{earth}_), 165 Jupiter-size (6R_{earth}<=R_p_<15R_{earth}_), and 19 up to twice the size of Jupiter (15R_{earth}_<=R_p_<22R_{earth}_). In the temperature range appropriate for the habitable zone, 54 candidates are found with sizes ranging from Earth-size to larger than that of Jupiter. Six are less than twice the size of the Earth. Over 74% of the planetary candidates are smaller than Neptune. Multi-candidate, transiting systems are frequent; 17% of the host stars have multi-candidate systems, and 34% of all the candidates are part of multi-candidate systems.
- ID:
- ivo://CDS.VizieR/J/ApJS/204/24
- Title:
- Kepler planetary candidates. III.
- Short Name:
- J/ApJS/204/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New transiting planet candidates are identified in 16 months (2009 May-2010 September) of data from the Kepler spacecraft. Nearly 5000 periodic transit-like signals are vetted against astrophysical and instrumental false positives yielding 1108 viable new planet candidates, bringing the total count up to over 2300. Improved vetting metrics are employed, contributing to higher catalog reliability. Most notable is the noise-weighted robust averaging of multi-quarter photo-center offsets derived from difference image analysis that identifies likely background eclipsing binaries. Twenty-two months of photometry are used for the purpose of characterizing each of the candidates. Ephemerides (transit epoch, T_0_, and orbital period, P) are tabulated as well as the products of light curve modeling: reduced radius (R_P_/R_*_), reduced semimajor axis (d/R_*_), and impact parameter (b).