T. C. Hinse

Kepler-413b: A Slightly Misaligned, Neptune-size Transiting Circumbinary Planet

We report the discovery of a transiting, Rp = 4.347 ± 0.099R ⊕, circumbinary planet (CBP) orbiting the Kepler K+M eclipsing binary (EB) system KIC 12351927 (Kepler-413) every ~66 days on an eccentric orbit with ap = 0.355 ± 0.002 AU, ep = 0.118 ± 0.002. The two stars, with MA = 0.820 ± 0.015 M ☉, RA = 0.776 ± 0.009 R ☉ and MB = 0.542 ± 0.008 M ☉, RB = 0.484 ± 0.024 R ☉, respectively, revolve around each other every 10.11615 ± 0.00001 days on a nearly circular (e EB = 0.037 ± 0.002) orbit. The orbital plane of the EB is slightly inclined to the line of sight (i EB = 8733 ± 006), while that of the planet is inclined by ~25 to the binary plane at the reference epoch. Orbital precession with a period of ~11 yr causes the inclination of the latter to the sky plane to continuously change. As a result, the planet often fails to transit the primary star at inferior conjunction, causing stretches of hundreds of days with no transits (corresponding to multiple planetary orbital periods). We predict that the next transit will not occur until 2020. The orbital configuration of the system places the planet slightly closer to its host stars than the inner edge of the extended habitable zone. Additionally, the orbital configuration of the system is such that the CBP may experience Cassini State dynamics under the influence of the EB, in which the planets obliquity precesses with a rate comparable to its orbital precession. Depending on the angular precession frequency of the CBP, it could potentially undergo obliquity fluctuations of dozens of degrees (and complex seasonal cycles) on precession timescales.

A GAS GIANT CIRCUMBINARY PLANET TRANSITING THE F STAR PRIMARY OF THE ECLIPSING BINARY STAR KIC 4862625 AND THE INDEPENDENT DISCOVERY AND CHARACTERIZATION OF THE TWO TRANSITING PLANETS IN THE KEPLER-47 SYSTEM

We report the discovery of a transiting, gas giant circumbinary planet orbiting the eclipsing binary KIC 4862625 and describe our independent discovery of the two transiting planets orbiting Kepler-47. We describe a simple and semi-automated procedure for identifying individual transits in light curves and present our follow-up measurements of the two circumbinary systems. For the KIC 4862625 system, the 0.52 {+-} 0.018 R{sub Jupiter} radius planet revolves every {approx}138 days and occults the 1.47 {+-} 0.08 M{sub Sun }, 1.7 {+-} 0.06 R{sub Sun} F8 IV primary star producing aperiodic transits of variable durations commensurate with the configuration of the eclipsing binary star. Our best-fit model indicates the orbit has a semi-major axis of 0.64 AU and is slightly eccentric, e = 0.1. For the Kepler-47 system, we confirm the results of Orosz et al. Modulations in the radial velocity of KIC 4862625A are measured both spectroscopically and photometrically, i.e., via Doppler boosting, and produce similar results.

PHYSICAL PROPERTIES OF THE 0.94-DAY PERIOD TRANSITING PLANETARY SYSTEM WASP-18 ⁄

We present high-precision photometry of five consecutive transits of WASP-18, an extrasolar planetary system with one of the shortest orbital periods known. Through the use of telescope defocusing we achieve a photometric precision of 0.47-0.83 mmag per observation over complete transit events. The data are analyzed using the JKTEBOP code and three different sets of stellar evolutionary models. We find the mass and radius of the planet to be M {sub b} = 10.43 +- 0.30 +- 0.24 M {sub Jup} and R {sub b} = 1.165 +- 0.055 +- 0.014 R {sub Jup} (statistical and systematic errors), respectively. The systematic errors in the orbital separation and the stellar and planetary masses, arising from the use of theoretical predictions, are of a similar size to the statistical errors and set a limit on our understanding of the WASP-18 system. We point out that seven of the nine known massive transiting planets (M {sub b} > 3 M {sub Jup}) have eccentric orbits, whereas significant orbital eccentricity has been detected for only four of the 46 less-massive planets. This may indicate that there are two different populations of transiting planets, but could also be explained by observational biases. Further radial velocitymorexa0» observations of low-mass planets will make it possible to choose between these two scenarios.«xa0less

High-precision photometry by telescope defocussing - II. The transiting planetary system WASP-4

We present high-precision photometry of two transit events of the extrasolar planetary system WASP-5, obtained with the Danish 1.54 m telescope at ESO La Silla. In order to minimise both random and flat-fielding errors, we defocussed the telescope so its point spread function approximated an annulus of diameter 40 pixels (16 00 ). Data reduction was undertaken using standard aperture photometry plus an algorithm for optimally combining the ensemble of comparison stars. The resulting light curves have point-to-point scatters of 0.50 mmag for the first transit and 0.59 mmag for the second. We construct detailed signal to noise calculations for defocussed photometry, and apply them to our observations. We model the light curves with the JKTEBOP code and combine the results with tabulated predictions from theoretical stellar evolutionary models to derive the physical properties of the WASP-5 system. We find that the planet has a mass of Mb = 1.637± 0.075± 0.033 MJup, a radius of Rb = 1.171± 0.056± 0.012 RJup, a large surface gravity of gb = 29.6± 2.8 m s i2 and a density of rb = 1.02±0.14±0.01 rJup (statistical and systematic uncertainties). The planet’s high equilibrium temperature of Teq = 1732± 80 K, makes it a good candidate for detecting secondary eclipses.

Kepler 453 b: the 10th Kepler Transiting Circumbinary Planet

We present the discovery of Kepler-453 b, a 6.2 R⊕ planet in a low-eccentricity, 240.5 day orbit about an eclipsing binary. The binary itself consists of a 0.94 and 0.195 M⊙ pair of stars with an orbital period of 27.32 days. The plane of the planets orbit is rapidly precessing, and its inclination only becomes sufficiently aligned with the primary star in the latter portion of the Kepler data. Thus three transits are present in the second half of the light curve, but none of the three conjunctions that occurred during the first half of the light curve produced observable transits. The precession period is ~103 years, and during that cycle, transits are visible only ~8.9% of the time. This has the important implication that for every system like Kepler-453 that we detect, there are ~11.5 circumbinary systems that exist but are not currently exhibiting transits. The planets mass is too small to noticeably perturb the binary, and consequently its mass is not measurable with these data; however, our photodynamical model places a 1σ upper limit of 16 M⊕. With a period 8.8 times that of the binary, the planet is well outside the dynamical instability zone. It does, however, lie within the habitable zone of the binary, making it the third of 10 Kepler circumbinary planets to do so.

A detailed investigation of the proposed NN Serpentis planetary system

The post-main-sequence eclipsing binary NN Serpentis was recently announced as the potential host of at least two massive planetary companions. In that work, the authors put forward two potential architectures that fit the observations of the eclipsing binary with almost identical precision. In this work, we present the results of a dynamical investigation of the orbital stability of both proposed system architectures, finding that they are only stable for scenarios in which the planets are locked in mutual mean motion resonance. In the discovery work, the authors artificially fixed the orbital eccentricity of the more massive planet, NN Ser (AB) c, at 0. Here, we reanalyse the observational data on NN Serpentis without this artificial constraint, and derive a new orbital solution for the two proposed planets. We detail the results of further dynamical simulations investigating the stability of our new orbital solution, and find that allowing a small non-zero eccentricity for the outer planet renders the system unstable. We conclude that although the original orbits proposed for the NN Serpentis planetary system prove dynamically feasible, further observations of the system are vital in order to better constrain the systems true architecture.

A detailed dynamical investigation of the proposed QS Virginis planetary system

In recent years, a number of planetary systems have been proposed to orbit-evolved binary star systems. The presence of planets is invoked to explain observed variations in the timing of mutual eclipses between the primary and secondary components of the binary star system. The planets recently proposed orbiting the cataclysmic variable system QS Virginis are the latest in this ongoing series of `extreme planets.The two planets proposed to orbit QS Virginis would move on mutually crossing orbits - a situation that is almost invariably unstable on very short time-scales. In this work, we present the results of a detailed dynamical study of the orbital evolution of the two proposed planets, revealing that they are dynamically unstable on time-scales of less than one thousand years across the entire range of orbital elements that provide a plausible fit to the observational data, and regardless of their mutual orbital inclination. We conclude that the proposed planets around the cataclysmic variable QS Virginis simply cannot exist.

OBSERVATIONAL AND DYNAMICAL CHARACTERIZATION OF MAIN-BELT COMET P/2010 R2 (La Sagra)

We present observations of the recently discovered comet-like main-belt object P/2010 R2 (La Sagra) obtained by Pan-STARRS1 and the Faulkes Telescope-North on Haleakala in Hawaii, the University of Hawaii 2.2 m, Gemini-North, and Keck I telescopes on Mauna Kea, the Danish 1.54 m telescope (operated by the MiNDSTEp consortium) at La Silla, and the Isaac Newton Telescope on La Palma. An antisolar dust tail is observed to be present from 2010 August through 2011 February, while a dust trail aligned with the objects orbit plane is also observed from 2010 December through 2011 August. Assuming typical phase darkening behavior, P/La Sagra is seen to increase in brightness by >1xa0mag between 2010 August and December, suggesting that dust production is ongoing over this period. These results strongly suggest that the observed activity is cometary in nature (i.e., driven by the sublimation of volatile material), and that P/La Sagra is therefore the most recent main-belt comet to be discovered. We find an approximate absolute magnitude for the nucleus of HR = 17.9 ± 0.2xa0mag, corresponding to a nucleus radius of ~0.7xa0km, assuming an albedo of p = 0.05. Comparing the observed scattering surface areas of the dust coma to that of the nucleus when P/La Sagra was active, we find dust-to-nucleus area ratios of Ad /AN = 30-60, comparable to those computed for fellow main-belt comets 238P/Read and P/2008 R1 (Garradd), and one to two orders of magnitude larger than for two other main-belt comets (133P/Elst-Pizarro and 176P/LINEAR). Using optical spectroscopy to search for CN emission, we do not detect any conclusive evidence of sublimation products (i.e., gas emission), finding an upper limit CN production rate of Q CN 100 Myr, suggesting that it is likely native to its current location and that its composition is likely representative of other objects in the same region of the main belt, though the relatively close proximity of the 13:6 mean-motion resonance with Jupiter and the (3,–2,–1) three-body mean-motion resonance with Jupiter and Saturn mean that dynamical instability on larger timescales cannot be ruled out.

On the HU Aquarii planetary system hypothesis

In this paper, we investigate the eclipse timing of the polar binary HUu2009Aquarii that has been observed for almost two decades. Recently, Qian et al. attributed large (O–C) deviations between the eclipse ephemeris and observations to a compact system of two massive Jovian companions. We improve the Keplerian, kinematic model of the light travel time effect and re-analyse the whole currently available data set. We add almost 60 new, yet unpublished, mostly precision light curves obtained using the time high-resolution photopolarimeter Optical Timing Analyzer (OPTIMA), as well as photometric observations performed at the Monitoring Network of Telescopes/North, Physics Innovations Robotic Astronomical Telescope Explorer and Carlos Sanchez Telescope. We determine new mid-egress times with a mean uncertainty at the level of 1u2009s or better. We claim that because the observations that currently exist in the literature are non-homogeneous with respect to spectral windows (ultraviolet, X-ray, visual and polarimetric mode) and the reported mid-egress measurements errors, they may introduce systematics that affect orbital fits. Indeed, we find that the published data, when taken literally, cannot be explained by any unique solution. Many qualitatively different and best-fit two-planet configurations, including self-consistent, Newtonian N-body solutions may be able to explain the data. However, using high-resolution, precision OPTIMA light curves, we find that the (O–C) deviations are best explained by the presence of a single circumbinary companion orbiting at a distance of ∼4.5u2009au with a small eccentricity and having ∼7 Jupiter masses. This object could be the next circumbinary planet detected from the ground, similar to the announced companions around close binaries HWu2009Vir, NNu2009Ser, UZu2009For, DPu2009Leo, FSu2009Aur or SZu2009Her, and planets of this type around Kepler-16, Kepler-34 and Kepler-35.

Application of the MEGNO technique to the dynamics of Jovian irregular satellites

We apply the Mean Exponential Growth Factor of Nearby Orbits (MEGNO) technique to the dynamics of Jovian irregular satellites. The MEGNO indicator is a practical numerical tool to distinguish between quasi-periodic and chaotic structures in phase space of a given dynamical system. The MEGNO indicator is used to generate a mapping of relevant phase-space regions occupied by observed Jovian irregular satellites. The construction of MEGNO maps of the Jovian phase-space region within its Hill-sphere is addressed and the obtained results are compared with previous studies regarding the dynamical stability of irregular satellites. Since this is the first time the MEGNO technique is applied to study the dynamics of irregular satellites, we provide a review of the MEGNO theory and illustrate basic properties. We consider the elliptic restricted three-body problem in which Jupiter is orbited by a massless test satellite subject to solar gravitational perturbations. The equations of motion of the system are integrated numerically and the MEGNO indicator computed from the systems variational equations. A large set of initial conditions is studied to generate the MEGNO maps. The chaotic nature of initial conditions is demonstrated by studying a quasi-periodic orbit and a chaotic orbit. As a result, we establish the existence of several high-order mean-motion resonances (MMR) detected for retrograde orbits along with other interesting dynamical features related to various dynamical resonances. The computed MEGNO maps allow us to differentiate qualitatively between chaotic and quasi-periodic regions of the irregular satellite phase space within a relatively short integration time of 60xa0000xa0yr for each orbit. By comparing with previous published results, we can establish a correlation between chaotic regions and corresponding regions of orbital instability. Based on our results, we hypothesize on the possibility of gravitational scattering from high-order MMR as a dynamical cause to explain the observed orbital velocity dispersion for members of the Pasiphae family.