HD 206893 B is a brown-dwarf companion orbiting inside the debris disk of its host star. We detect the brown dwarf in the Ms band using the Keck/NIRC2 instrument and vortex coronagraph. We measure its magnitude to be Ms=12.97(-0.11)(0.10). It is at an angular separation of 0.'' 22 +/- 0.'' 03, and a position angle of 39.6 degrees +/- 5.4 degrees east of north. Using this Ms-band measurement and the system age, we use three evolutionary models to estimate the mass to be 12-78 M (Jup). We analyze the atmospheric properties from 1-5 mu m using a grid of simulated atmospheric models. We find that a sedimentation flux f (sed) value similar to 0.2 provides the best fit to the data, suggesting high vertically extended clouds. This may be indicative of high-altitude grains or a circumplanetary disk. Our model radii and luminosities for the companion find the best fits are ages of <100 Myr and masses <20 M-Jup, consistent with our mass estimate from the evolutionary models using the Ms-band data alone. We detect orbital motion of the brown dwarf around the host star in comparison to the discovery image and derive orbital parameters. Finally we analyze how the companion brown dwarf interacts with the debris disk by estimating the location of the chaotic zone around the brown dwarf using values derived from this study's estimated mass and orbital constraints. We find that the collisions within the debris belt are likely driven by secular perturbations from the brown dwarf, rather than self-stirring.

High resolution imaging (HRI) is a critical part of the transiting exoplanet follow-up and validation process. HRI allows previously unresolved stellar companions and background blends to be resolved, vetting false positive signals and improving the radii measurements of true planets. Through a multi-semester Keck NIRC2 adaptive optics imaging program, we have pursued HRI of K2 and TESS candidate planet host systems to provide the transiting exoplanet community with necessary data for system validation and characterization. Here we present a summary of our ongoing program that includes an up to date list of targets observed, a description of the observations and data reduction, and a discussion of planetary systems validated by the community using these data. This observing program has been key in NASA's K2 and TESS missions reaching their goals of identifying new exoplanets ideal for continued follow-up observations to measure their masses and investigate their atmospheres. Once processed, all observations presented here are available as calibrated images and resulting contrast curves through the Exoplanet Follow-up Observing Program (ExoFOP) website. We encourage members of the exoplanet community to use these data products in their ongoing planetary system validation and characterization efforts.

We present the first polarimetric detection of the inner disk component around the pre-main sequence B9.5 star HD 141569A. Gemini Planet Imager H-band (1.65 micron) polarimetric differential imaging reveals the highest signal-to-noise ratio detection of this ring yet attained and traces structure inwards to 0.25" (28 AU at a distance of 111 pc). The radial polarized intensity image shows the east side of the disk, peaking in intensity at 0.40" (44 AU) and extending out to 0.9" (100 AU). There is a spiral arm-like enhancement to the south, reminiscent of the known spiral structures on the outer rings of the disk. The location of the spiral arm is coincident with 12CO J=3-2 emission detected by ALMA, and hints at a dynamically active inner circumstellar region. Our observations also show a portion of the middle dusty ring at 220 AU known from previous observations of this system. We fit the polarized H-band emission with a continuum radiative transfer Mie model. Our best-fit model favors an optically thin disk with a minimum dust grain size close to the blow-out size for this system: evidence of on-going dust production in the inner reaches of the disk. The thermal emission from this model accounts for virtually all of the far-infrared and millimeter flux from the entire HD 141569A disk, in agreement with the lack of ALMA continuum and CO emission beyond 100 AU. A remaining 8-30 micron thermal excess a factor of 2 above our model argues for a yet-unresolved warm innermost 5-15 AU component of the disk.

K2 observations of the weak-lined T Tauri binary V928 Tau A and B show the detection of a single, asymmetric eclipse, which may be due to a previously unknown substellar companion eclipsing one component of the binary with an orbital period >66 days. Over an interval of about 9 hr, one component of the binary dims by around 60%, returning to its normal brightness about 5 hr later. From modeling of the eclipse shape, we find evidence that the eclipsing companion may be surrounded by a disk or a vast ring system. The modeled disk has a radius of 0.9923 0.0005 R-*, with an inclination of 5678 003, a tilt of 4122 005, an impact parameter of -0.2506 0.0002 R-*, and an opacity of 1.00. The occulting disk must also move at a transverse velocity of 6.637 0.002 R-* day(-1), which, depending on whether it orbits V928 Tau A or B, corresponds to approximately 73.53 or 69.26 km s(-1). A search in ground-based archival data reveals additional dimming events, some of which suggest periodicity, but no unambiguous period associated with the eclipse observed by K2. We present a new epoch of astrometry that is used to further refine the orbit of the binary, presenting a new lower bound of 67 yr, and constraints on the possible orbital periods of the eclipsing companion. The binary is also separated by 18 '' (similar to 2250 au) from the lower-mass CFHT-BD-Tau 7, which is likely associated with V928 Tau A and B. We also present new high-dispersion optical spectroscopy that we use to characterize the unresolved stellar binary.

This dataset contains transit model posterior distributions and validation analyses for the 275 exoplanet candidates (in 233 systems) analyzed in Mayo et al. (2018), titled "275 Candidates and 149 Validated Planets Orbiting Bright Stars in K2 Campaigns 0-10". The dataset takes the form of 233 compressed directories each corresponding to an exoplanet system and titled after its EPIC ID. Within a given directory there are two numpy pickles named EPICXXXXXXXXX_chains.npy and EPICXXXXXXXXX_lnlikes.npy (where XXXXXXXXX is the 9 digit EPIC number) as well as n subdirectories, where n is the number of planet candidates in the system. The EPICXXXXXXXXX_chains.npy pickle is a representative sample of the posterior distribution of the transit model for a given exoplanet system. The pickle is a numpy array of size (j,k,l), where j is the number of walkers in the Markov chain Monte Carlo ensemble simulation that sampled the posterior distribution (note: we chose to fix j = 2*l), k is the number of walker steps reported in this dataset (the full posteriors were thinned down to between 750 and 10,000 steps), and l is the number of parameters in the transit model for the exoplanet system. The EPICXXXXXXXXX_lnlikes.npy pickle contains the associated ln(likelihood) values for each walker step in the previously described pickle. This pickle is a numpy array of size (j,k) where j and k are defined as above. The number of parameters will always be of the form 4 + 5*n, where n is again the number of planets in the systems. The first four parameters in the pickle are a baseline offset parameter for the normalized flux, a noise parameter to take the place of flux error bars, and two quadratic limb darkening parameters q1 and q2 based on Kipping et al. (2013). The next five parameters (and each subsequent set of five parameters in multi-candidate systems) refer to the reference epoch (a mid-transit time in BJD - 2454833), the period (in days), log10(Rp/R*), the transit duration (TIV-TI in days), and the impact parameter. It should be noted that there is no consistent ordering of the planets in the posterior samples (for example, in a three planet system parameters 5-9 may refer to planet b, planet c, or planet d). Therefore, planetary periods should be used as reference to identify candidates. All parameters and the nature of the transit model are described in detail in Mayo et al. (2018). Each subdirectory contains the input and output of the validation analysis conducted via the VESPA validation package (Morton 2012, 2015). For additional details please refer to the relevant citations or the VESPA github repository. Each subdirectory is named after the appropriate candidate listed in Mayo et al. (2018; specifically Tables 5 and 7).

We present the discovery of the giant planet KELT-19Ab, which transits the moderately bright ( ) A8V star TYC 764-1494-1 with an orbital period of 4.61 days. We confirm the planetary nature of the companion via a combination of radial velocities, which limit the mass to ( ), and a clear Doppler tomography signal, which indicates a retrograde projected spin–orbit misalignment of degrees. Global modeling indicates that the K host star has and . The planet has a radius of and receives a stellar insolation flux of , leading to an inferred equilibrium temperature of K assuming zero albedo and complete heat redistribution. With a , the host is relatively slowly rotating compared to other stars with similar effective temperatures, and it appears to be enhanced in metallic elements but deficient in calcium, suggesting that it is likely an Am star. KELT-19A would be the first detection of an Am host of a transiting planet of which we are aware. Adaptive optics observations of the system reveal the existence of a companion with late-G9V/early-K1V spectral type at a projected separation of . Radial velocity measurements indicate that this companion is bound. Most Am stars are known to have stellar companions, which are often invoked to explain the relatively slow rotation of the primary. In this case, the stellar companion is unlikely to have caused the tidal braking of the primary. However, it may have emplaced the transiting planetary companion via the Kozai–Lidov mechanism.

We report the discovery of a Neptune-size planet (Rp = 3.0 Re) in the Hyades Cluster. The host star is in a binary system, comprising a K5V star and M7/8V star with a projected separation of 40 AU. The planet orbits the primary star with an orbital period of 17.3 days and a transit duration of 3 hours. The host star is bright (V=11.2, J=9.1) and so may be a good target for precise radial velocity measurements. K2-136A c is the first Neptune-sized planet to be found orbiting in a binary system within an open cluster. The Hyades is the nearest star cluster to the Sun, has an age of 625-750 Myr, and forms one of the fundamental rungs in the distance ladder; understanding the planet population in such a well-studied cluster can help us understand and set constraints on the formation and evolution of planetary systems.

Since 2014, NASA’s K 2 mission has observed large portions of the ecliptic plane in search of transiting planets and has detected hundreds of planet candidates. With observations planned until at least early 2018, K 2 will continue to identify more planet candidates. We present here 275 planet candidates observed during Campaigns 0–10 of the K 2 mission that are orbiting stars brighter than 13 mag (in Kepler band) and for which we have obtained high-resolution spectra ( R = 44,000). These candidates are analyzed using the vespa package in order to calculate their false-positive probabilities (FPP). We find that 149 candidates are validated with an FPP lower than 0.1%, 39 of which were previously only candidates and 56 of which were previously undetected. The processes of data reduction, candidate identification, and statistical validation are described, and the demographics of the candidates and newly validated planets are explored. We show tentative evidence of a gap in the planet radius distribution of our candidate sample. Comparing our sample to the Kepler candidate sample investigated by Fulton et al., we conclude that more planets are required to quantitatively confirm the gap with K 2 candidates or validated planets. This work, in addition to increasing the population of validated K 2 planets by nearly 50% and providing new targets for follow-up observations, will also serve as a framework for validating candidates from upcoming K 2 campaigns and the Transiting Exoplanet Survey Satellite , expected to launch in 2018.

We report the discovery of KELT-20b, a hot Jupiter transiting a V similar to 7.6 early A star, HD 185603, with an orbital period of P similar or equal to 3.47 days. Archival and follow-up photometry, Gaia parallax, radial velocities, Doppler tomography, and AO imaging were used to confirm the planetary nature of KELT-20b and characterize the system. From global modeling we infer that KELT-20 is a rapidly rotating (v sin I* similar or equal to 120 km s(-1)) A2V star with an effective temperature of T-eff 8730(-260)(+250) K, mass of M* = 1.76(-0.20)(+0.14) M-circle dot, radius of R* = 1.561(-0.064)(+0.058) R-circle dot, surface gravity of log g* = 4.292(-0.020)(+0.017), and age of less than or similar to 600 Myr. The planetary companion has a radius of R-p = 1.735(-0.075)(+0.070) R-J, a semimajor axis of a = 0.0542(-0.0021)(+0.0014) au, and a linear ephemeris of BJD(TDB) = 2457503.120049 +/- 0.000190 + E(3.4741070 +/- 0.0000019). We place a 3 sigma upper limit of similar to 3.5 M-J on the mass of the planet. Doppler tomographic measurements indicate that the planetary orbit normal is well aligned with the projected spin axis of the star (lambda = 3 degrees.4 +/- 2 degrees.1). The inclination of the star is constrained to 24 degrees.4 < I* < 155 degrees.6, implying a three-dimensional spin-orbit alignment of 1 degrees.3 < psi < 69 degrees.8. KELT-20b receives an insolation flux of similar to 8 x 10(9) erg s(-1) cm(-2), implying an equilibrium temperature of of similar to 2250 K, assuming zero albedo and complete heat redistribution. Due to the high stellar T-eff, KELT-20b also receives an ultraviolet (wavelength d <= 91.2 nm) insolation flux of similar to 9.1 x 10(4) erg s(-1) cm(-2), possibly indicating significant atmospheric ablation. Together with WASP-33, Kepler-13 A, HAT-P-57, KELT-17, and KELT-9, KELT-20 is the sixth A star host of a transiting giant planet, and the third-brightest host (in V) of a transiting planet.

We report the discovery of a Neptune-size planet (Rp = 3.0 Re) in the Hyades Cluster. The host star is in a binary system, comprising a K5V star and M7/8V star with a projected separation of 40 AU. The planet orbits the primary star with an orbital period of 17.3 days and a transit duration of 3 hours. The host star is bright (V=11.2, J=9.1) and so may be a good target for precise radial velocity measurements. K2-136A c is the first Neptune-sized planet to be found orbiting in a binary system within an open cluster. The Hyades is the nearest star cluster to the Sun, has an age of 625-750 Myr, and forms one of the fundamental rungs in the distance ladder; understanding the planet population in such a well-studied cluster can help us understand and set constraints on the formation and evolution of planetary systems.

We report the discovery of a Neptune-size planet (Rp = 3.0 Re) in the Hyades Cluster. The host star is in a binary system, comprising a K5V star and M7/8V star with a projected separation of 40 AU. The planet orbits the primary star with an orbital period of 17.3 days and a transit duration of 3 hours. The host star is bright (V=11.2, J=9.1) and so may be a good target for precise radial velocity measurements. K2-136A c is the first Neptune-sized planet to be found orbiting in a binary system within an open cluster. The Hyades is the nearest star cluster to the Sun, has an age of 625-750 Myr, and forms one of the fundamental rungs in the distance ladder; understanding the planet population in such a well-studied cluster can help us understand and set constraints on the formation and evolution of planetary systems.

We present spectrophotometry spanning 1–5 μm of 51 Eridani b, a 2–10 planet discovered by the Gemini Planet Imager Exoplanet Survey. In this study, we present new K1 (1.90–2.19 μm) and K2 (2.10–2.40 μm) spectra taken with the Gemini Planet Imager as well as an updated LP (3.76 μm) and new MS (4.67 μm) photometry from the NIRC2 Narrow camera. The new data were combined with J (1.13–1.35 μm) and H (1.50–1.80 μm) spectra from the discovery epoch with the goal of better characterizing the planet properties. The 51 Eri b photometry is redder than field brown dwarfs as well as known young T-dwarfs with similar spectral type (between T4 and T8), and we propose that 51 Eri b might be in the process of undergoing the transition from L-type to T-type. We used two complementary atmosphere model grids including either deep iron/silicate clouds or sulfide/salt clouds in the photosphere, spanning a range of cloud properties, including fully cloudy, cloud-free, and patchy/intermediate-opacity clouds. The model fits suggest that 51 Eri b has an effective temperature ranging between 605 and 737 K, a solar metallicity, and a surface gravity of log(g) = 3.5–4.0 dex, and the atmosphere requires a patchy cloud atmosphere to model the spectral energy distribution (SED). From the model atmospheres, we infer a luminosity for the planet of −5.83 to −5.93 ( ), leaving 51 Eri b in the unique position of being one of the only directly imaged planets consistent with having formed via a cold-start scenario. Comparisons of the planet SED against warm-start models indicate that the planet luminosity is best reproduced by a planet formed via core accretion with a core mass between 15 and 127 .

The science investigation teams (SITs) for the WFIRST coronagraphic instrument have begun studying the capabilities of the instrument to directly image reflected light off from exoplanets at contrasts down to contrasts of ~10^-9 with respect to the stellar flux. Detection of point sources at these high contrasts requires yield estimates and detailed modeling of the image of the planetary system as it propagates through the telescope optics. While the SITs might generate custom astrophysical scenes, the integrated model, propagated through the internal speckle field, is typically done at JPL. In this white paper, we present a standard file format to ensure a single distribution system between those who produce the raw astrophysical scenes, and JPL modelers who incorporate those scenes into their optical modeling. At its core, our custom file format uses FITS files, and incorporates standards on packaging astrophysical scenes. This includes spectral and astrometric information for planetary and stellar point sources, zodiacal light and extragalactic sources that may appear as contaminants. Adhering to such a uniform data distribution format is necessary, as it ensures seamless work flow between the SITs and modelers at JPL for the goals of understanding limits of the WFIRST coronagraphic instrument.

In an earlier study, we reported nearly 100 previously unknown dusty debris disks around Hipparcos main sequence stars within 75 pc by selecting stars with excesses in individual WISE colors. Here, we further scrutinize the Hipparcos 75 pc sample to (1) gain sensitivity to previously undetected, fainter mid-IR excesses and (2) remove spurious excesses contaminated by previously unidentified blended sources. We improve on our previous method by adopting a more accurate measure of the confidence threshold for excess detection and by adding an optimally weighted color average that incorporates all shorter-wavelength WISE photometry, rather than using only individual WISE colors. The latter is equivalent to spectral energy distribution fitting, but only over WISE bandpasses. In addition, we leverage the higher-resolution WISE images available through the unWISE.me image service to identify contaminated WISE excesses based on photocenter offsets among the W3- and W4-band images. Altogether, we identify 19 previously unreported candidate debris disks. Combined with the results from our earlier study, we have found a total of 107 new debris disks around 75 pc Hipparcos main-sequence stars using precisely calibrated WISE photometry. This expands the 75 pc debris disk sample by 22% around Hipparcos main sequence stars and by 20% overall (including non-main-sequence and non-Hipparcos stars).

A principal scientific goal of the Gemini Planet Imager (GPI) is obtaining milliarcsecond astrometry to constrain exoplanet orbits. However, astrometry of directly imaged exoplanets is subject to biases, systematic errors, and speckle noise. Here, we describe an analytical procedure to forward model the signal of an exoplanet that accounts for both the observing strategy (angular and spectral differential imaging) and the data reduction method (Karhunen–Loève Image Projection algorithm). We use this forward model to measure the position of an exoplanet in a Bayesian framework employing Gaussian processes and Markov-chain Monte Carlo to account for correlated noise. In the case of GPI data on β Pic b, this technique, which we call Bayesian KLIP-FM Astrometry (BKA), outperforms previous techniques and yields 1σ errors at or below the one milliarcsecond level. We validate BKA by fitting a Keplerian orbit to 12 GPI observations along with previous astrometry from other instruments. The statistical properties of the residuals confirm that BKA is accurate and correctly estimates astrometric errors. Our constraints on the orbit of β Pic b firmly rule out the possibility of a transit of the planet at 10-σ significance. However, we confirm that the Hill sphere of β Pic b will transit, giving us a rare chance to probe the circumplanetary environment of a young, evolving exoplanet. We provide an ephemeris for photometric monitoring of the Hill sphere transit event, which will begin at the start of April in 2017 and finish at the end of January in 2018.