- ID:
- ivo://CDS.VizieR/J/AJ/144/42
- Title:
- Infrared photometry of 90 KOIs
- Short Name:
- J/AJ/144/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- All transiting planets are at risk of contamination by blends with nearby, unresolved stars. Blends dilute the transit signal, causing the planet to appear smaller than it really is, or produce a false-positive detection when the target star is blended with eclipsing binary stars. This paper reports on high spatial-resolution adaptive optics images of 90 Kepler planetary candidates. Companion stars are detected as close as 0.1" from the target star. Images were taken in the near-infrared (J and 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%) have at least one companion within 2" of the target star; six companions (7%) are closer than 0.5". Most of these companions were previously unknown, and the associated planetary candidates should receive additional scrutiny. Limits are placed on the presence of additional companions for every system observed, which can be used to validate planets statistically using the BLENDER method. Validation is particularly critical for low-mass, potentially Earth-like worlds, which are not detectable with current-generation radial velocity techniques. High-resolution images are thus a crucial component of any transit follow-up program.
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- ID:
- ivo://CDS.VizieR/J/AJ/152/182
- Title:
- iz follow-up photometry of HAT-P-65 and HAT-P-66
- Short Name:
- J/AJ/152/182
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of the transiting exoplanets HAT-P-65b and HAT-P-66b, with orbital periods of 2.6055 and 2.9721 days, masses of 0.527+/-0.083M_J_ and 0.783+/-0.057M_J_, and inflated radii of 1.89+/-0.13R_J_ and 1.59_-0.10_^+0.16^R_J_, respectively. They orbit moderately bright (V=13.145+/-0.029 and V=12.993+/-0.052) stars of mass 1.212+/-0.050M_{Sun}_ and 1.255_-0.054_^+0.107^M_{Sun}_. The stars are at the main-sequence turnoff. While it is well known that the radii of close-in giant planets are correlated with their equilibrium temperatures, whether or not the radii of planets increase in time as their hosts evolve and become more luminous is an open question. Looking at the broader sample of well-characterized close-in transiting giant planets, we find that there is a statistically significant correlation between planetary radii and the fractional ages of their host stars, with a false-alarm probability of only 0.0041%. We find that the correlation between the radii of planets and the fractional ages of their hosts is fully explained by the known correlation between planetary radii and their present-day equilibrium temperatures; however, if the zero-age main-sequence equilibrium temperature is used in place of the present-day equilibrium temperature, then a correlation with age must also be included to explain the planetary radii. This suggests that, after contracting during the pre-main-sequence, close-in giant planets are reinflated over time due to the increasing level of irradiation received from their host stars. Prior theoretical work indicates that such a dynamic response to irradiation requires a significant fraction of the incident energy to be deposited deep within the planetary interiors.
- ID:
- ivo://CDS.VizieR/J/MNRAS/456/2636
- Title:
- Kepler-10 chemical composition
- Short Name:
- J/MNRAS/456/2636
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemical abundance studies of the Sun and solar twins have demonstrated that the solar composition of refractory elements is depleted when compared to volatile elements, which could be due to the formation of terrestrial planets. In order to further examine this scenario, we conducted a line-by-line differential chemical abundance analysis of the terrestrial planet host Kepler-10 and 14 of its stellar twins. Stellar parameters and elemental abundances of Kepler-10 and its stellar twins were obtained with very high precision using a strictly differential analysis of high quality Canada-France-Hawaii Telescope, Hobby-Eberly Telescope and Magellan spectra. When compared to the majority of thick disc twins, Kepler-10 shows a depletion in the refractory elements relative to the volatile elements, which could be due to the formation of terrestrial planets in the Kepler-10 system. The average abundance pattern corresponds to ~13 Earth masses, while the two known planets in Kepler-10 system have a combined ~20 Earth masses. For two of the eight thick disc twins, however, no depletion patterns are found. Although our results demonstrate that several factors [e.g. planet signature, stellar age, stellar birth location and Galactic chemical evolution (GCE)] could lead to or affect abundance trends with condensation temperature, we find that the trends give further support for the planetary signature hypothesis.
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/3561
- Title:
- Kepler eclipsing binary stars. K2 Campaign 0
- Short Name:
- J/MNRAS/452/3561
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The original Kepler mission observed and characterized over 2400 eclipsing binaries (EBs) in addition to its prolific exoplanet detections. Despite the mechanical malfunction and subsequent non-recovery of two reaction wheels used to stabilize the instrument, the Kepler satellite continues collecting data in its repurposed K2 mission surveying a series of fields along the ecliptic plane. Here, we present an analysis of the first full baseline K2 data release: the Campaign 0 data set. In the 7761 light curves we have identified a total of 207 EBs. Of these, 97 are new discoveries that were not previously identified. Our pixel-level analysis of these objects has also resulted in identification of several false positives (observed targets contaminated by neighbouring EBs), as well as the serendipitous discovery of two short-period exoplanet candidates. We provide catalogue cross-matched source identifications, orbital periods, morphologies and ephemerides for these eclipsing systems. We also describe the incorporation of the K2 sample into the Kepler Eclipsing Binary Catalog, present spectroscopic follow-up observations for a limited selection of nine systems and discuss prospects for upcoming K2 campaigns.
- 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.
- 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/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/810/95
- Title:
- Kepler pipeline S/N studies. II. 2011 data
- Short Name:
- J/ApJ/810/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kepler planet sample can only be used to reconstruct the underlying planet occurrence rate if the detection efficiency of the Kepler pipeline is known; here we present the results of a second experiment aimed at characterizing this detection efficiency. We inject simulated transiting planet signals into the pixel data of ~10000 targets, spanning one year of observations, and process the pixels as normal. We compare the set of detections made by the pipeline with the expectation from the set of simulated planets, and construct a sensitivity curve of signal recovery as a function of the signal-to-noise of the simulated transit signal train. The sensitivity curve does not meet the hypothetical maximum detection efficiency; however, it is not as pessimistic as some of the published estimates of the detection efficiency. For the FGK stars in our sample, the sensitivity curve is well fit by a gamma function with the coefficients a=4.35 and b=1.05. We also find that the pipeline algorithms recover the depths and periods of the injected signals with very high fidelity, especially for periods longer than 10 days. We perform a simplified occurrence rate calculation using the measured detection efficiency compared to previous assumptions of the detection efficiency found in the literature to demonstrate the systematic error introduced into the resulting occurrence rates. The discrepancies in the calculated occurrence rates may go some way toward reconciling some of the inconsistencies found in the literature.
