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 (FPPs) for all of the transiting planets (41 of 42 have an FPP under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than three times 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 six planets with densities above 5 g cm −3 , suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than ∼2 R ⊕. Larger planets evidently contain a larger fraction of low-density material (H, He, and H 2 O).
Main TextKepler is a NASA Discovery-class mission designed to determine the frequency of Earth-radius planets in and near the HZ of solar-like stars (1-6). Planets are detected as "transits" that cause the host star to appear periodically fainter when the planets pass in front it along the observer's line of sight. Kepler-62 (KIC 9002278, KOI 701) is one of approximately 170,000 stars observed by the Kepler spacecraft. Based on an analysis of long-cadence photometric observations from Kepler taken in Quarters 1 through 12 (May 13, 2009 through March 28, 2012, we report the detection of five planets including two super-Earth-size planets in the HZ and a hot Mars-size planet orbiting Kepler-62 ( Fig. 1 and Table 1). Prior to validation, three of these objects were designated as planetary candidates 701.02, and 701.03 in the Kepler 2011 catalog (7) and the Kepler 2012 catalog (8). KOI-701.04 and 701.05 were identified subsequently using a larger data sample (9).Analysis of high-resolution spectra indicates that Kepler-62 is a K2V spectral type with an estimated mass and radius (in solar units) of 0.69 ± 0.02 Mʘ and 0.63 ± 0.02 Rʘ (9). Examination of the sky close to Kepler-62 showed the presence of only one additional star that contributed as much as 1% to the total flux (figs. S3-S4)(9). Warm-Spitzer observations ( fig. S9) and the analysis of centroid motion (Table S1) were consistent with the target star as the source of the transit signals ( Fig. 1 and fig. S1). We computed the radius, semi-major axis, and radiative equilibrium 3 temperature of each planet (Table 1) based on light curve modeling given the derived stellar parameters (Table S3). Fig. 1. Kepler-62 light curves after the data were detrended to remove the stellar variability. Composite of phase-folded transit light curves (dots), data binned in ½ hour intervals (blue error bars), and model fits (colored curves) for Kepler-62b through -62f. Model parameters are provided in Table 1. The error bars get larger as the period becomes larger because there are fewer points to bin together. For the shortest periods, the bars are too small to see. Notes: 1) T 0 is the epoch in mid-transit in Barycentric Julian Days, P is the period, duration is the transit duration, "depth" is the percent reduction of the flux during the transits determined from the model fit to the data, R p /R * is the ratio of the radius of the planet to the radius of the star, a/R * is the ratio of the planet's semi-major axis to the stellar radius, b is the impact parameter in units of stellar radius, i is the orbital inclination, ecosω is the product of the orbital eccentricity e with the cosine of the periapse angle ω, a is the semi-major axis, and R p is the radius of the planet, and Maximum Mass is the upper limit to the mass based on transiting timing and RV observations, M⊕ is the mass of the Earth, and Teq is the radiative equilibrium temperature.2) The values of the uncertainties are ±1 standard deviation unless otherwise noted.3) Values for the maximum mass are for the 95 th p...
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 M and 0.979 +/-0.020 R . The depth of 492 ± 10ppm for the three observed transits yields a radius of 2.38 +/-0.13 Re 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 3σ upper limit of 124 M , 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.
To date a dozen transiting "Tatooines" or circumbinary planets (CBPs) have been discovered, by eye, in the data from the Kepler mission; by contrast, thousands of confirmed circumstellar planets orbiting around single stars have been detected using automated algorithms. Automated detection of CBPs is challenging because their transits are strongly aperiodic with irregular profiles. Here, we describe an efficient and automated technique for detecting circumbinary planets that transit their binary hosts in Kepler light curves. Our method accounts for large transit timing and duration variations (TTVs and TDVs), induced by binary reflex motion, in two ways: 1) We directly correct for large-scale TTVs and TDVs in the light curves by using Keplerian models to approximate binary and CBP orbits; and 2) We allow additional aperiodicities on the corrected light curves by employing the Quasi-periodic Automated Transit Search algorithm (QATS). We demonstrate that our method dramatically improves detection significance using simulated data and two previously identified CBP systems, Kepler -35 and Kepler -64.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.