Latest in astro-ph.ep

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Towards Efficient Detection of Small Near-Earth Asteroids Using the Zwicky Transient Facility (ZTF)Apr 21 2019We describe ZStreak, a semi-real-time pipeline specialized in detecting small, fast-moving near-Earth asteroids (NEAs) that is currently operating on the data from the newly-commissioned Zwicky Transient Facility (ZTF) survey. Based on a prototype originally ... More
Surface slopes of asteroid pairs as indicators of mechanical properties and cohesionApr 21 2019Asteroid pairs had a single progenitor that split due to rotational-fission of a weak, rubble-pile structured body. By constructing shape models of asteroid pairs from multiple-apparition observations and using a lightcurve inversion technique, we mapped ... More
Analytic computation of the secular effects of encounters on a binary: features arising from second-order perturbation theoryApr 21 2019Binary-single interactions play a crucial role in the evolution of dense stellar systems such as globular clusters. In addition, they are believed to drive black hole (BH) binary mergers in these systems. A subset of binary-single interactions are secular ... More
3-micron Reflectance Spectroscopy of Carbonaceous Chondrites under Asteroid-like ConditionsApr 20 2019We measured 3-micron reflectance spectra of 21 meteorites that represent all carbonaceous chondrite types available in terrestrial meteorite collections. The measurements were conducted at the Laboratory for Spectroscopy under Planetary Environmental ... More
Identification of organic molecules with a laboratory prototype based on the Laser Ablation-CosmOrbitrapApr 20 2019In the Solar System, extra-terrestrial organic molecules have been found on cometary primitive objects, on Titan and Enceladus icy moons and on Mars. Identification could be achieved for simple organic species by remote sensing based on spectroscopic ... More
Exoplanet Reflected Light Spectroscopy with PICASOApr 19 2019Here we present the first open-source radiative transfer model for computing the reflected light of exoplanets at any phase geometry, called PICASO: Planetary Intensity Code for Atmospheric Scattering Observations. This code, written in Python, has heritage ... More
On the dynamics of Comet 1P/Halley: Lyapunov and power spectraApr 19 2019Using a purely Newtonian model for the Solar System, we investigate the dynamics of comet 1P/Halley considering in particular the Lyapunov and power spectra of its orbit, using the nominal initial conditions of JPL's Horizons system. We carry out precise ... More
A survey of C2H, HCN, and C18O in protoplanetary disksApr 19 2019Molecular lines observed towards protoplanetary disks carry information about physical and chemical processes associated with planet formation. We present ALMA Band 6 observations of C2H, HCN, and C18O in a sample of 14 disks spanning a range of ages, ... More
Line Ratios Reveal N2H+ Emission Originates Above the Midplane in TW HydraeApr 19 2019Line ratios for different transitions of the same molecule have long been used as a probe of gas temperature. Here we use ALMA observations of the N2H+ J~=~1-0 and J~=~4-3 lines in the protoplanetary disk around TW Hya to derive the temperature at which ... More
Photometry of active Centaurs: Colors of dormant active Centaur nucleiApr 19 2019We present multiband photometric observations of nine Centaurs. Five of the targets are known active Centaurs (167P/CINEOS, 174P/Echeclus, P/2008 CL94, P/2011 S1, and C/2012 Q1), and the other four are inactive Centaurs belonging to the redder of the ... More
The digest2 NEO Classification CodeApr 19 2019We describe the digest2 software package, a fast, short-arc orbit classifier for small Solar System bodies. The digest2 algorithm has been serving the community for more than 13 years. The code provides a score, D2, which represents a pseudo-probability ... More
Terrestrial deuterium-to-hydrogen ratio in water in hyperactive cometsApr 19 2019The D/H ratio in cometary water has been shown to vary between 1 and 3 times the Earth's oceans value, in both Oort cloud comets and Jupiter-family comets originating from the Kuiper belt. We present new sensitive spectroscopic observations of water isotopologues ... More
Unexpectedly strong effect of supergranulation on the detectability of Earth twins orbiting Sun-like stars with radial velocitiesApr 19 2019Magnetic activity and surface flows at different scales pertub radial velocity measurements. This affects the detectability of low-mass exoplanets. In these flows, the effect of supergranulation is not as well characterized as the other flows, and we ... More
New and Extended Data Processing of Mars Odyssey Neutron Spectrometer DataApr 18 2019The Los Alamos National Laboratory designed and built Mars Odyssey Neutron Spectrometer (MONS) has been in excellent health operating from February 2002 to the present. MONS measures the neutron leakage albedo from galactic cosmic ray bombardment of Mars. ... More
Constraints on a Putative Planet Sculpting the V4046 Sagittarii Circumbinary DiskApr 18 2019We analyze the highest-resolution millimeter continuum and near-infrared (NIR) scattered-light images presented to date of the circumbinary disk orbiting V4046 Sgr, a ~20 Myr old actively accreting, close binary T Tauri star system located a mere 72.4 ... More
Blue, white, and red ocean planets - Simulations of orbital variations in flux and polarization colorsApr 18 2019An exoplanet's habitability will depend strongly on the presence of liquid water. Flux and/or polarization measurements of starlight that is reflected by exoplanets could help to identify exo-oceans. We investigate which broadband spectral features in ... More
Non-ideal MHD simulation of HL Tau disk: formation of ringsApr 18 2019Recent high resolution observations unveil ring structures in circumstellar disks. The origin of these rings has been widely investigated under various theoretical scenarios. In this work we perform global 3D non-ideal MHD simulations including effects ... More
Shaping Asteroids with Genetic Evolution (SAGE)Apr 18 2019In this work we present SAGE (Shaping Asteroid models using Genetic Evolution) asteroid modelling algorithm based solely on photometric lightcurve data. It produces non-convex shapes, rotation axes orientati and rotational periods of asteroids. The main ... More
Debris Disk Composition: A Diagnostic Tool for Planet Formation and MigrationApr 18 2019Debris disks are exoplanetary systems containing planets, minor bodies (such as asteroids and comets) and debris dust. Unseen planets are presumed to perturb the minor bodies into crossing orbits, generating small dust grains that are detected via remote ... More
Why do some probabilistic forecasts lack reliability?Apr 18 2019In this work, we investigate the reliability of the probabilistic binary forecast. We mathematically prove that a necessary, but not sufficient, condition for achieving a reliable probabilistic forecast is maximizing the Peirce skill score (PSS) at the ... More
Search for nearby Earth analogs I. 15 planet candidates found in PFS dataApr 18 2019The radial velocity method plays a major role in the discovery of nearby exoplanets. To efficiently find planet candidates from the data obtained in high precision radial velocity surveys, we apply a signal diagnostic framework to detect radial velocity ... More
Mars Obliquity History Constrained by Elliptic Crater OrientationsApr 17 2019The dynamics of Mars' obliquity are believed to be chaotic, and the historical ~3.5 Gyr (late-Hesperian onward) obliquity probability density function (PDF) is high uncertain and cannot be inferred from direct simulation alone. Obliquity is also a strong ... More
Linking the evolution of terrestrial interiors and an early outgassed atmosphere to astrophysical observationsApr 17 2019A terrestrial planet is molten during formation and may remain so if subject to intense insolation or tidal forces. Observations continue to favour the detection and characterisation of hot planets, potentially with large outgassed atmospheres. We aim ... More
Stellar activity and planetary atmosphere evolution in tight binary star systemsApr 17 2019Context. In tight binary star systems, tidal interactions can significantly influence the rotational and orbital evolution of both stars, and therefore their activity evolution. This can have strong effects on the atmospheric evolution of planets that ... More
The origin of the cratering asymmetry on TritonApr 17 2019The source of impactors capable of producing the cratering asymmetry on Triton is open to debate. While hyperbolic comets are the likely source of impactors, the theoretically predicted crater distribution due to impacts from comets is incompatible with ... More
NGTS-6b: An Ultra Hot-Jupiter Orbiting a Metal-rich starApr 16 2019We report the discovery of a new ultra hot Jupiter from the Next Generation Transit Survey. NGTS-6b orbits its star with a period of 21.17 h, and has a mass and radius of $1.330^{+0.024}_{-0.028}\,M_J$ and $1.271^{+0.197}_{-0.188}\,R_J$ respectively. ... More
NGTS-6b: An Ultra Hot-Jupiter Orbiting a Metal-rich starApr 16 2019Apr 18 2019We report the discovery of a new ultra hot Jupiter from the Next Generation Transit Survey. NGTS-6b orbits its star with a period of 21.17 h, and has a mass and radius of $1.330^{+0.024}_{-0.028}\,M_\text{J}$ and $1.271^{+0.197}_{-0.188}\,R_\text{J}$ ... More
Automated crater detection on Mars using deep learningApr 16 2019Impact crater cataloging is an important tool in the study of the geological history of planetary bodies in the Solar System, including dating of surface features and geologic mapping of surface processes. Catalogs of impact craters have been created ... More
Could there be an undetected inner planet near the stability limit in Kepler-1647?Apr 16 2019Kepler-1647b is the most recently discovered planet that transits two stars, i.e., a circumbinary planet (CBP). Due to its large orbital separation, Kepler-1647b stands out from the rest of the Kepler CBPs, which mostly reside on much tighter orbits near ... More
Seasonal structures in Saturn's dusty Roche Division correspond to periodicities of the planet's magnetosphereApr 16 2019We identify multiple periodic dusty structures in Saturn's Roche Division, a faint region spanning the $\sim3000$ km between the A and F rings. The locations and extent of these features vary over Cassini's tour of the Saturn system, being visible in ... More
Spontaneous ring formation in wind-emitting accretion discsApr 16 2019Rings and gaps have been observed in a wide range of protoplanetary discs, from young systems like HLTau to older discs like TW Hydra. Recent disc simulations have shown that magnetohydrodynamic (MHD) turbulence (in the ideal or non-ideal regime) can ... More
The Keplerian three-body encounter II. Comparisons with isolated encounters and impact on gravitational wave merger timescalesApr 16 2019We investigate the role of the Keplerian tidal field generated by a supermassive black hole (SMBH) on the three-body dynamics of stellar mass black holes. We consider two scenarios occurring close to the SMBH: the breakup of unstable triples and three-body ... More
The Keplerian three-body encounter II. Comparisons with isolated encounters and impact on gravitational wave merger timescalesApr 16 2019Apr 18 2019We investigate the role of the Keplerian tidal field generated by a supermassive black hole (SMBH) on the three-body dynamics of stellar mass black holes. We consider two scenarios occurring close to the SMBH: the breakup of unstable triples and three-body ... More
Using Cosmogenic Lithium, Beryllium and Boron to Determine the Surface Ages of Icy Objects in the Outer Solar SystemApr 16 2019Given current uncertainties in the cratering rates and geological histories of icy objects in the outer solar system, it is worth considering how the ages of icy surfaces could be constrained with measurements from future landed missions. A promising ... More
OGLE-2017-BLG-1186: first application of asteroseismology and Gaussian processes to microlensingApr 16 2019We present the analysis of the event OGLE-2017-BLG-1186 from the 2017 $Spitzer$ microlensing campaign. This event is remarkable because its source is photometrically variable. We perform an asteroseismic analysis of the source star and find that it is ... More
Orbital decay of short-period gas giants under evolving tidesApr 16 2019The discovery of many giant planets in close-in orbits and the effect of planetary and stellar tides in their subsequent orbital decay have been extensively studied in the context of planetary formation and evolution theories. Planets orbiting close to ... More
Potential softening and eccentricity dynamics in razor-thin, nearly-Keplerian discsApr 16 2019In many astrophysical problems involving discs (gaseous or particulate) orbiting a dominant central mass, gravitational potential of the disc plays an important dynamical role. Its impact on the motion of external objects, as well as on the dynamics of ... More
Long-term Hydrodynamic Simulations on the Planetesimals in MMRsApr 16 2019The resonant perturbations from planets are able to halt the drag-induced migration, and capture the inwardly drifting planetesimals into mean motion resonances. The equilibrium eccentricity of planetesimals in resonances, and the minimum size of planetesimal ... More
Long-term Hydrodynamic Simulations on the Planetesimals Trapped in the First-order Mean Motion ResonancesApr 16 2019Apr 17 2019The resonant perturbations from planets are able to halt the drag-induced migration, and capture the inwardly drifting planetesimals into mean motion resonances. The equilibrium eccentricity of planetesimals in resonances, and the minimum size of planetesimal ... More
The footprint of cometary dust analogues: II. Morphology as a tracer of tensile strength and application to dust collection by the Rosetta spacecraftApr 16 2019The structure of cometary dust is a tracer of growth processes in the formation of planetesimals. Instrumentation on board the Rosetta mission to comet 67P/Churyumov- Gerasimenko captured dust particles and analysed them in situ. However, these deposits ... More
Principal Components of Short-term Variability in Venus' UV AlbedoApr 16 2019We explore the dominant modes of variability in the observed albedo at the cloud tops of Venus using the Akatsuki UVI 283-nm and 365-nm observations, which are sensitive to SO2 and unknown UV absorber distributions respectively, over the period Dec 2016 ... More
Modelling DESTINY+ interplanetary and interstellar dust measurements en route to the active asteroid (3200) PhaethonApr 16 2019The JAXA/ISAS spacecraft DESTINY$^+$ will be launched to the active asteroid (3200) Phaethon in 2022. Among the proposed core payload is the DESTINY+ Dust Analyzer (DDA) which is an upgrade of the Cosmic Dust Analyzer flown on the Cassini spacecraft to ... More
Excitation of Planetary Obliquities Through Planet-Disk InteractionsApr 15 2019The tilt of a planet's spin axis off its orbital axis ("obliquity") is a basic physical characteristic that plays a central role in determining the planet's global circulation and energy redistribution. Moreover, recent studies have also highlighted the ... More
Causation of Late Quaternary Rapid-increase Radiocarbon AnomaliesApr 15 2019Brief (less than 100 years) rapid-increase anomalies in the Earth's atmospheric radiocarbon production have previously been attributed to either gamma photon radiation from supernovae or to cosmic ray particle radiation from exceptionally large solar ... More
APEX Observations of the CO Envelope around the Young FUor-type Star V883 OriApr 15 2019The accretion-driven outbursts of young FU Orionis-type stars may be a common stage of pre-main sequence evolution and can have a significant impact on the circumstellar environment as it pertains to the growth of solids and eventually planets. This episodic ... More
Discovery of a Third Transiting Planet in the Kepler-47 Circumbinary SystemApr 15 2019Of the nine confirmed transiting circumbinary planet systems, only Kepler-47 is known to contain more than one planet. Kepler-47 b (the "inner planet") has an orbital period of 49.5 days and a radius of about $3\,R_{\oplus}$. Kepler-47 c (the "outer planet") ... More
Discovery of a Meteor of Interstellar OriginApr 15 2019The first interstellar object, `Oumuamua, was discovered in the Solar System by Pan-STARRS in 2017, allowing for a calibration of the abundance of interstellar objects of its size $\sim 100\;$ m. One would expect a much higher abundance of smaller interstellar ... More
Discovery of a Meteor of Interstellar OriginApr 15 2019Apr 20 2019The first interstellar object, `Oumuamua, was discovered in the Solar System by Pan-STARRS in 2017, allowing for a calibration of the abundance of interstellar objects of its size $\sim 100\;$ m. One would expect a much higher abundance of smaller interstellar ... More
The surprisingly low carbon mass in the debris disk around HD 32297Apr 15 2019Apr 17 2019Gas has been detected in a number of debris disks. It is likely secondary in nature and produced by the colliding solids in these disks. Here, we used ALMA Band 8 to observe emission from neutral carbon at 492 GHz in the CO-rich debris disk around the ... More
The surprisingly low carbon mass in the debris disk around HD 32297Apr 15 2019Gas has been detected in a number of debris disks. It is likely secondary in nature and produced by the colliding solids in these disks. Here, we used ALMA Band 8 to observe emission from neutral carbon at 492 GHz in the CO-rich debris disk around the ... More
Impacts of Quantum Chemistry Calculations on Exoplanetary Science, Planetary Astronomy, and AstrophysicsApr 15 2019Several of NASA missions (TESS, JWST, WFIRST, etc.) and mission concepts (LUVOIR, HabEx, and OST) emphasize the exploration and characterization of exoplanets, and the study of the interstellar medium. We anticipate that a much broader set of chemical ... More
Episodically Active Asteroid 6478 GaultApr 15 2019We present imaging and spectroscopic observations of 6478 Gault, a 6 km diameter inner main-belt asteroid currently exhibiting strong, comet-like characteristics. Three distinct tails indicate that ultra-slow dust (ejection speed 0.15+/-0.05 m/s) was ... More
Infrared Spectroscopy of Large, Low-Albedo Asteroids: Are Ceres and Themis Archetypes or Outliers?Apr 15 2019Low-albedo, hydrated objects dominate the list of the largest asteroids. These objects have varied spectral shapes in the 3-$\mu$m region, where diagnostic absorptions due to volatile species are found. Dawn's visit to Ceres has extended the view shaped ... More
Cooling in the shade of warped transition disksApr 15 2019The mass of the gaseous reservoir in young circumstellar disks is a crucial initial condition for the formation of planetary systems, but estimates vary by orders of magnitude. In some disks with resolvable cavities, sharp inner disk warps cast two-sided ... More
Accurate modelling of the low-order secondary resonances in the spin-orbit problemApr 15 2019We provide an analytical approximation to the dynamics in each of the three most important low order secondary resonances (1:1, 2:1, and 3:1) bifurcating from the synchronous primary resonance in the gravitational spin-orbit problem. To this end we extend ... More
Evolution of three-dimensional Relativistic Ion Weibel Instability: Competition with Kink InstabilityApr 15 2019In this paper, we report our recent findings on the relativistic Weibel instability and its nonlinear saturation by performing numerical simulations of collisionless plasmas. Analysis of the obtained numerical results revealed that the nonlinear phase ... More
Dispersion forces stabilise ice coatings at certain gas hydrate interfaces which prevent water wettingApr 13 2019Gas hydrates formed in oceans and permafrost occur in vast quantities on Earth representing both a massive potential fuel source and a large threat in climate forecasts. They have been predicted to be important on other bodies in our solar systems such ... More
The Ophiuchus DIsk Survey Employing ALMA (ODISEA): Disk Dust Mass Distributions across Protostellar Evolutionary ClassesApr 13 2019As protostars evolve from optically faint / infrared bright (Class I) sources to optically bright / infrared faint (Class II) the solid material in their surrounding disks accumulates into planetesimals and protoplanets. The nearby, young Ophiuchus star-forming ... More
On the Mass Function, Multiplicity, and Origins of Wide-Orbit Giant PlanetsApr 12 2019A major outstanding question regarding the formation of planetary systems is whether wide-orbit giant planets form differently than close-in giant planets. We aim to establish constraints on two key parameters that are relevant for understanding the formation ... More
On the Mass Function, Multiplicity, and Origins of Wide-Orbit Giant PlanetsApr 12 2019Apr 16 2019A major outstanding question regarding the formation of planetary systems is whether wide-orbit giant planets form differently than close-in giant planets. We aim to establish constraints on two key parameters that are relevant for understanding the formation ... More
Martian cloud climatology and life cycle extracted from Mars Express OMEGA spectral imagesApr 12 2019A Martian water-ice cloud climatology has been extracted from OMEGA data covering 7 Martian years (MY 26-32). We derived two products, the Reversed Ice Cloud Index (ICIR) and the Percentage of Cloudy Pixels (PCP), indicating the mean cloud thickness and ... More
Seasonal Water "Pump" in the Atmosphere of Mars: Vertical Transport to the ThermosphereApr 12 2019We present results of simulations with the Max Planck Institute general circulation model (MPI-MGCM) implementing a hydrological cycle scheme. The simulations reveal a seasonal water "pump" mechanism responsible for the upward transport of water vapor. ... More
Multiband photometry of a Patroclus-Menoetius mutual event: Constraints on surface heterogeneityApr 12 2019We present the first complete multiband observations of a binary asteroid mutual event. We obtained high-cadence, high-signal-to-noise photometry of the UT 2018 April 9 inferior shadowing event in the Jupiter Trojan binary system Patroclus-Menoetius in ... More
Meteor shower forecasting in near-Earth spaceApr 12 2019NASA's Meteoroid Environment Office (MEO) produces an annual meteor shower forecast in order to help spacecraft operators assess the risk posed by meteoroid streams. Previously, this forecast focused on the International Space Station and therefore reported ... More
Indications for transit timing variations in the exo-Neptune HAT-P-26bApr 12 2019From its discovery, the low density transiting Neptune HAT-P-26b showed a 2.1-sigma detection drift in its spectroscopic data, while photometric data showed a weak curvature in the timing residuals that required further follow-up observations to be confirmed. ... More
"TNOs are Cool": A survey of the trans-Neptunian region XIV. Size/albedo characterization of the Haumea family observed with Herschel and SpitzerApr 12 2019A group of trans-Neptunian objects (TNO) are dynamically related to the dwarf planet 136108 Haumea. Ten of them show strong indications of water ice on their surfaces, are assumed to have resulted from a collision, and are accepted as the only known TNO ... More
Pushing the Limits of Exoplanet Discovery via Direct Imaging with Deep LearningApr 12 2019Further advances in exoplanet detection and characterisation require sampling a diverse population of extrasolar planets. One technique to detect these distant worlds is through the direct detection of their thermal emission. The so-called direct imaging ... More
Tiny Grains Shining Bright in the Gaps of Herbig Ae Transitional DiscsApr 12 2019This work presents a study of two Herbig Ae transitional discs, Oph IRS 48 and HD 169142; which both have reported rings in their dust density distributions. We use Keck-II/NIRC2 adaptive optics imaging observations in the L' filter (3.8 micron) to probe ... More
Developing a vision for exoplanetary transit spectroscopy: a shared window on the analysis of planetary atmospheres and of stellar magnetic structureApr 11 2019We describe how the accurate characterization of exoplanetary atmospheres in the ELT and JWST era will inevitably require taking into consideration the stellar inhomogeneities caused by convection and magnetic fields. The existing evidence that demonstrates ... More
DeepStreaks: identifying fast-moving objects in the Zwicky Transient Facility data with deep learningApr 11 2019We present DeepStreaks, a convolutional-neural-network, deep-learning system designed to efficiently identify streaking fast-moving near-Earth objects that are detected in the data of the Zwicky Transient Facility (ZTF), a wide-field, time-domain survey ... More
The unbiased frequency of planetary signatures around single and binary white dwarfs using ${\it Spitzer}$ and ${\it Hubble}$Apr 11 2019This paper presents combined ${\it Spitzer}$ IRAC and ${\it Hubble}$ COS results for a double-blind survey of 195 single and 22 wide binary white dwarfs for infrared excesses and atmospheric metals. The selection criteria include cooling ages in the range ... More
Dynamical cartography of Earth satellite orbitsApr 11 2019We have carried out a numerical investigation of the coupled gravitational and non-gravitational perturbations acting on Earth satellite orbits in an extensive grid, covering the whole circumterrestrial space, using an appropriately modified version of ... More
Medium Earth Orbit dynamical survey and its use in passive debris removalApr 11 2019The Medium Earth Orbit (MEO) region hosts satellites for navigation, communication, and geodetic/space environmental science, among which are the Global Navigation Satellites Systems (GNSS). Safe and efficient removal of debris from MEO is problematic ... More
Dynamical Lifetime Survey of Geostationary Transfer OrbitsApr 11 2019In this paper, we study the long-term dynamical evolution of highly-elliptical orbits (HEOs) in the medium-Earth orbit (MEO) region around the Earth. The real population consists primarily of Geosynchronous Transfer Orbits (GTOs), launched at specific ... More
Reducing activity-induced variations in a radial-velocity time series of the Sun as a starApr 11 2019The radial velocity of the Sun as a star is affected by its surface convection and magnetic activity. The moments of the cross-correlation function between the solar spectrum and a binary line mask contain information about the stellar radial velocity ... More
Local manifestations of cometary activityApr 11 2019Comets are made of volatile and refractory material and naturally experience various degrees of sublimation as they orbit around the Sun. This gas release, accompanied by dust, represents what is traditionally described as activity. Although the basic ... More
Is there more than meets the eye? Presence and role of submicron grains in debris discsApr 10 2019The presence of submicron grains has been inferred in several debris discs, despite the fact that these particles should be blown out by stellar radiation pressure on very short timescales. So far, no fully satisfying explanation has been found for this ... More
First Light of Engineered Diffusers at the Nordic Optical Telescope Reveal Time Variability in the Optical Eclipse Depth of WASP-12bApr 10 2019We present the characterization of two engineered diffusers mounted on the 2.5 meter Nordic Optical Telescope, located at Roque de Los Muchachos, Spain. To assess the reliability and the efficiency of the diffusers, we carried out several test observations ... More
On degeneracies in retrievals of exoplanetary transmission spectraApr 10 2019Accurate estimations of atmospheric properties of exoplanets from transmission spectra require understanding of degeneracies between model parameters and observations that can resolve them. We conduct a systematic investigation of such degeneracies using ... More
The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics From 10-100 AUApr 10 2019We present a statistical analysis of the first 300 stars observed by the Gemini Planet Imager Exoplanet Survey (GPIES). This subsample includes six detected planets and three brown dwarfs; from these detections and our contrast curves we infer the underlying ... More
Inertial Modes in Near-Spherical GeometriesApr 10 2019We propose a numerical method to compute the inertial modes of a container with near-spherical geometry based on the fully spectral discretisation of the angular and radial directions using spherical harmonics and Gegenbauer polynomial expansion respectively. ... More
Magnetohydrodynamics in a Cylindrical Shearing BoxApr 10 2019Apr 11 2019We develop a framework for magnetohydrodynamical (MHD) simulations in a local cylindrical shearing box by extending the formulation of the Cartesian shearing box. We construct shearing-periodic conditions at the radial boundaries of a simulation box from ... More
Magnetohydrodynamics in a Cylindrical Shearing BoxApr 10 2019We develop a framework for magnetohydrodynamical (MHD) simulations in a local cylindrical shearing box by extending the formulation of the Cartesian shearing box. We construct shearing-periodic conditions at the radial boundaries of a simulation box from ... More
Transiting Planets near the Snow Line from Kepler. I. CatalogApr 10 2019We present a comprehensive catalog of cool (period $P\gtrsim 2\,\mathrm{yr}$) transiting planet candidates in the four-year light curves from the prime \kepler\ mission. Most of the candidates show only one or two transits and have largely been missed ... More
The dynamics of rings around Centaurs and Trans-Neptunian ObjectsApr 09 2019Since 2013, dense and narrow rings are known around the small Centaur object Chariklo and the dwarf planet Haumea. Dense material has also been detected around the Centaur Chiron, although its nature is debated. This is the first time ever that rings ... More
Astro 2020 Science White Paper: Evolved Planetary Systems around White DwarfsApr 09 2019Apr 12 2019Practically all known planet hosts will evolve into white dwarfs, and large parts of their planetary systems will survive this transition - the same is true for the solar system beyond the orbit of Mars. Spectroscopy of white dwarfs accreting planetary ... More
Astro 2020 Science White Paper: Evolved Planetary Systems around White DwarfsApr 09 2019Practically all known planet hosts will evolve into white dwarfs, and large parts of their planetary systems will survive this transition - the same is true for the solar system beyond the orbit of Mars. Spectroscopy of white dwarfs accreting planetary ... More
The binary mass ratios of circumbinary planet hostsApr 09 2019Almost a dozen circumbinary planets have been found transiting eclipsing binaries. For the first time the observational bias of this sample is calculated with respect to the mass ratio of the host binaries. It is shown that the mass ratio affects transit ... More
Faster Water Escape on High Obliquity PlanetsApr 09 2019We investigate how obliquity affects stratospheric humidity using a 3D general circulation model and find the stratosphere under high obliquity could be over 5 orders of magnitude moister than under the low obliquity equivalent, even with the same global ... More
Forbush decreases and $<$ 2-day GCR flux non-recurrent variations studied with LISA PathfinderApr 09 2019Non-recurrent short term variations of the galactic cosmic-ray (GCR) flux above 70 MeV n$^{-1}$ were observed between 2016 February 18 and 2017 July 3 aboard the European Space Agency LISA Pathfinder (LPF) mission orbiting around the Lagrange point L1 ... More
Explicit IMF $B_y$-effect maximizes at subauroral latitudes (Dedicated to the memory of Eigil Friis-Christensen)Apr 09 2019The most important parameter in the coupling between solar wind and geomagnetic activity is the $B_z$-component of the interplanetary magnetic field (IMF). However, recent studies have shown that IMF $B_y$ is an additional, independent driver of geomagnetic ... More
Stellar activity and rotation of the planet host Kepler-17 from long-term space-borne photometryApr 09 2019The study of young Sun-like stars is of fundamental importance to understand the magnetic activity and rotational evolution of the Sun. Space-borne photometry by the Kepler telescope provides unprecedented datasets to investigate these phenomena in Sun-like ... More
Decomposition of Amino Acids in Water with Application to In-Situ Measurements of Enceladus, Europa and Other Hydrothermally Active Icy Ocean WorldsApr 09 2019To test the potential of using amino acid abundances as a biosignature at icy ocean worlds, we investigate whether primordial amino acids (accreted or formed by early aqueous processes) could persist until the present time. By examining the decomposition ... More
X-ray Studies of Exoplanets: A 2020 Decadal Survey White PaperApr 08 2019Over the last two decades, the discovery of exoplanets has fundamentally changed our perception of the universe and humanity's place within it. Recent work indicates that a solar system's X-ray and high energy particle environment is of fundamental importance ... More
Modelling H$_{3}^{+}$ in planetary atmospheres: effects of vertical gradients on observed quantitiesApr 08 2019Apr 10 2019Since its discovery in the aurorae of Jupiter ~30 years ago, the H$_{3}^{+}$ ion has served as an invaluable probe of giant planet upper atmospheres. However, the vast majority of monitoring of planetary H$_{3}^{+}$ radiation has followed from observations ... More
Modelling H$_{3}^{+}$ in planetary atmospheres: effects of vertical gradients on observed quantitiesApr 08 2019Since its discovery in the aurorae of Jupiter ~30 years ago, the H$_{3}^{+}$ ion has served as an invaluable probe of giant planet upper atmospheres. However, the vast majority of monitoring of planetary H$_{3}^{+}$ radiation has followed from observations ... More
Exoplanet atmospheres with GIANO II. Detection of molecular absorption in the dayside spectrum of HD 102195bApr 08 2019The study of exoplanetary atmospheres is key to understand the differences between their physical, chemical and dynamical processes. Up to now, the bulk of atmospheric characterization analysis has been conducted on transiting planets. On some sufficiently ... More
Normalization of the Levi-Civita Hamiltonian at a collinear Lagrange pointApr 08 2019The normalizations of the Hamiltonian of the circular restricted three-body problem at a collinear Lagrange equilibrium are used to compute approximations of its center and tube manifolds, as well as of all the dynamics in their neighbourhood. For small ... More
Lessons from early Earth: UV surface radiation should not limit the habitability of active M star systemsApr 08 2019The closest potentially habitable worlds outside our Solar system orbit a different kind of star than our Sun: smaller red dwarf stars. Such stars can flare frequently, bombarding their planets with biologically damaging high-energy UV radiation, placing ... More
How stars and planets interact: a look through the high-energy windowApr 08 2019The architecture of exoplanetary systems is often different from the solar system, with some exoplanets being in close orbits around their host stars and having orbital periods of only a few days. In analogy to interactions between stars in close binary ... More