In this paper we search for distant massive companions to known transiting gas giant planets that may have influenced the dynamical evolution of these systems. We present new radial velocity observations for a sample of 51 planets obtained using the Keck HIRES instrument, and find statistically significant accelerations in fifteen systems. Six of these systems have no previously reported accelerations in the published literature: HAT-P-10, HAT-P-22, HAT-P-29, HAT-P-32, WASP-10, and XO-2. We combine our radial velocity fits with Keck NIRC2 adaptive optics (AO) imaging data to place constraints on the allowed masses and orbital periods of the companions responsible for the detected accelerations. The estimated masses of the companions range between 1 − 500 M Jup , with orbital semi-major axes typically between 1 − 75 AU. A significant majority of the companions detected by our survey are constrained to have minimum masses comparable to or larger than those of the transiting planets in these systems, making them candidates for influencing the orbital evolution of the inner gas giant. We estimate a total occurrence rate of 51 ± 10% for companions with masses between 1 − 13 M Jup and orbital semi-major axes between 1 − 20 AU in our sample. We find no statistically significant difference between the frequency of companions to transiting planets with misaligned or eccentric orbits and those with well-aligned, circular orbits. We combine our expanded sample of radial velocity measurements with constraints from transit and secondary eclipse observations to provide improved measurements of the physical and orbital characteristics of all of the planets included in our survey.

The Kepler space telescope detects exoplanets by measuring periodic dimmings of light as a planet passes in front of its host star (1). The majority of the ∼ 150,000 targets observed by Kepler are unevolved stars near the main sequence, because those stars provide the best prospect for detecting habitable planets similar to Earth (2). In contrast, the temperature and surface gravity of indicate that it is an evolved star with exhausted hydrogen in its core, and that it started burning hydrogen in a shell surrounding an inert Helium core. Stellar evolutionary theory predicts that our Sun will evolve into a low-luminosity red giant similar in size to Kepler-56 in roughly 7 billion years.The Kepler planet search pipeline detected two planet candidates orbiting (designated as KOI-1241) (3) with periods of 10.50 and 21.41 days, a nearly 2:1 commensurability. The observation of transit time variations caused by gravitational interactions 2 showed that the two candidates represent objects orbiting the same star, and modeling of these variations led to upper limits on their masses that place them firmly in the planetary regime (4). Kepler-56 is the most evolved star observed by Kepler with more than one detected planet.Transit observations lead to measurements of planet properties relative to stellar properties, and hence accurate knowledge of the host star is required to characterize the system. Asteroseismology enables inference of stellar properties through the measurement of oscillations excited by near-surface convection (5). The power spectrum of the Kepler-56 data after removing the planetary transits shows a regular series of peaks ( Fig. 1), which are characteristic of stellar oscillations. By combining the measured oscillation frequencies with the effective temperature and chemical composition obtained from spectroscopy, we were able to precisely determine the properties of the host star (6). Kepler-56 is more than four times as large as the Sun and its mass is 30% greater (Table 1).Non-radial oscillations in evolved stars are mixed modes, behaving like pressure modes in the envelope and like gravity modes in the core (7,8). Unlike pressure-dominated mixed modes, gravity-dominated mixed modes have frequencies that are shifted from the regular asymptotic spacing. Mixed modes are also approximately equally spaced in period (9). We measured the average period spacing between dipole (l = 1) modes in Kepler-56 to be 50 seconds, consistent with a first ascent red giant (10).Individual mixed dipole modes are further split into multiplets as a result of stellar rotation. Because the modes in each multiplet are on average expected to be excited to very nearly equal amplitudes, the observed relative amplitudes depend only on viewing angle relative to the stellar rotation axis (11). For Kepler-56 several mixed dipole modes show triplets (Fig. 1). A rotation axis perpendicular to the line of sight (inclination i = 90 • for pressure-dominated modes. Simulations confirmed that the inclination measurements are not strongly...

The ensemble of chemical element abundance measurements for stars, along with precision distances and orbit properties, provides high-dimensional data to study the evolution of the Milky Way. With this third data release of the Galactic Archaeology with HERMES (GALAH) survey, we publish 678 423 spectra for 588 571 mostly nearby stars (81.2% of stars are within < 2 kpc), observed with the HERMES spectrograph at the Anglo-Australian Telescope. This release (hereafter GALAH+ DR3) includes all observations from GALAH Phase 1 (bright, main, and faint survey, 70%), K2-HERMES (17%), TESS-HERMES (5%), and a subset of ancillary observations (8%) including the bulge and > 75 stellar clusters. We derive stellar parameters Teff, log g, [Fe/H], vmic, vbroad, and vradusing our modified version of the spectrum synthesis code Spectroscopy Made Easy (sme) and 1D marcs model atmospheres. We break spectroscopic degeneracies in our spectrum analysis with astrometry from Gaia DR2 and photometry from 2MASS. We report abundance ratios [X/Fe] for 30 different elements (11 of which are based on non-LTE computations) covering five nucleosynthetic pathways. We describe validations for accuracy and precision, flagging of peculiar stars/measurements and recommendations for using our results. Our catalogue comprises 65% dwarfs, 34% giants, and 1% other/unclassified stars. Based on unflagged chemical composition and age, we find 62% young low-α, 9% young high-α, 27% old high-α, and 2% stars with [Fe/H] ≤ −1. Based on kinematics, 4% are halo stars. Several Value-Added-Catalogues, including stellar ages and dynamics, updated after GaiaeDR3, accompany this release and allow chrono-chemodynamic analyses, as we showcase.

During its two year prime mission the Transiting Exoplanet Survey Satellite (TESS) will perform a time-series photometric survey covering over 80% of the sky. This survey comprises observations of 26 24 • × 96 • sectors that are each monitored continuously for approximately 27 days. The main goal of TESS is to find transiting planets around 200,000 pre-selected stars for which fixed aperture photometry is recorded every two minutes. However, TESS is also recording and delivering Full-Frame Images (FFIs) of each detector at a 30 minute cadence. We have created an open-source tool, eleanor, to produce light curves for objects in the TESS FFIs. Here, we describe the methods used in eleanor to produce light curves that are optimized for planet searches. The tool performs background subtraction, aperture and PSF photometry, decorrelation of instrument systematics, and cotrending using principal component analysis. We recover known transiting exoplanets in the FFIs to validate the pipeline and perform a limited search for new planet candidates in Sector 1. Our tests indicate that eleanor produces light curves with significantly less scatter than other tools that have been used in the literature. Cadence-stacked images, and raw and detrended eleanor light curves for each analyzed star will be hosted on MAST, with planet candidates on ExoFOP-TESS as Community TESS Objects of Interest (CTOIs). This work confirms the promise that the TESS FFIs will enable the detection of thousands of new exoplanets and a broad range of time domain astrophysics.

Doppler-based planet surveys have discovered numerous giant planets but are incomplete beyond several AU. At larger star-planet separations direct planet detection through high-contrast imaging has proven successful, but this technique is sensitive only to young planets and characterization relies upon theoretical evolution models. Here we demonstrate radial velocity measurements and high-contrast imaging can be combined to overcome these issues. The presence of widely separated companions can be deduced by identifying an acceleration (long-term trend) in the radial velocity of a star. By obtaining high spatial resolution follow-up imaging observations, we rule out scenarios in which such accelerations are caused by stellar binary companions with high statistical confidence. We report results from an analysis of Doppler measurements of a sample of 111 M-dwarf stars with a median of 29 radial velocity observations over a median time baseline of 11.8 years. By targeting stars that exhibit a radial velocity acceleration ("trend") with adaptive optics imaging, we determine that 6.5 ± 3.0% of M dwarf stars host one or more massive companions with 1 < m/M J < 13 and 0 < a < 20 AU. These results are lower than analyses of the planet occurrence rate around higher mass stars. We find the giant planet occurrence rate is described by a double power law in stellar mass M and metallicity F ≡[Fe/H] such that f (M, F ) = 0.039 +0.056 −0.028 M 0.8 +1.1 −0.9 10 (3.8±1.2)F . Our results are consistent with gravitational microlensing measurements of the planet occurrence rate; this study represents the first model-independent comparison with microlensing observations.

Photometry of stars from the K2 extension of NASA's Kepler mission is afflicted by systematic effects caused by small (few-pixel) drifts in the telescope pointing and other spacecraft issues. We present a method for searching K2 light curves for evidence of exoplanets by simultaneously fitting for these systematics and the transit signals of interest. This method is more computationally expensive than standard search algorithms but we demonstrate that it can be efficiently implemented and used to discover transit signals. We apply this method to the full Campaign 1 dataset and report a list of 36 planet candidates transiting 31 stars, along with an analysis of the pipeline performance and detection efficiency based on artificial signal injections and recoveries. For all planet candidates, we present posterior distributions on the properties of each system based strictly on the transit observables.

The magnetic activity of the Sun and other stars causes their brightness to vary. We investigated how typical the Sun’s variability is compared with other solar-like stars, i.e., those with near-solar effective temperatures and rotation periods. By combining 4 years of photometric observations from the Kepler space telescope with astrometric data from the Gaia spacecraft, we were able to measure photometric variabilities of 369 solar-like stars. Most of those with well-determined rotation periods showed higher variability than the Sun and are therefore considerably more active. These stars appear nearly identical to the Sun except for their higher variability. Therefore, we speculate that the Sun could potentially also go through epochs of such high variability.

The Kepler space telescope has opened new vistas in exoplanet discovery space by revealing populations of Earth-sized planets that provide a new context for understanding planet formation. Approximately 70% of all stars in the Galaxy belong to the diminutive M dwarf class, several thousand of which lie within Kepler's field of view, and a large number of these targets show planet transit signals.The Kepler M dwarf sample has a characteristic mass of 0.5 M ⊙ representing a stellar population twice as common as Sun-like stars. Kepler-32 is a typical star in this sample that presents us with a rare opportunity: five planets transit this star giving us an expansive view of its architecture. All five planets of this compact system orbit their host star within a distance one third the size of Mercury's orbit with the innermost planet positioned a mere 4.3 stellar radii from the stellar photosphere. New observations limit possible false positive scenarios allowing us to validate the entire Kepler-32 system making it the richest known system of transiting planets around an M dwarf. Based on considerations of the stellar dust sublimation radius, a minimum mass protoplanetary nebula, and the near period commensurability of three adjacent planets, we propose that the Kepler-32 planets formed at larger orbital radii and migrated inward to their present locations. The volatile content inferred for the Kepler-32 planets and order of magnitude estimates for the disk migration rates suggest these planets may have formed beyond the snow line and migrated in the presence of a gaseous disk. If true, this would place an upper limit on their formation time of ∼ 10 Myr. The Kepler-32 planets are representative of the full ensemble of planet candidates orbiting the Kepler M dwarfs for which we calculate an occurrence rate of 1.0 ± 0.1 planet per star. The formation of the Kepler-32 planets therefore offers a plausible blueprint for the formation of one of the largest known populations of planets in our Galaxy. Subject headings: planetary systems -methods: statistical -planets and satellites: formation -planets and satellites: detection -stars: individual (KID 9787239/KOI-952/Kepler-32)