Results for "Mark C. Wyatt"

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Signatures of Planets in the Observable Structure of Circumstellar Debris DisksFeb 22 2000Recent advances in astronomical instrumentation mean that we are now able to image the thermal emission from the disks of dust around main sequence stars that may be the fossil remnants of planetary formation. These observations imply that the distribution ... More
The Solar System's Post-Main Sequence Escape BoundaryJan 11 2012The Sun will eventually lose about half of its current mass nonlinearly over several phases of post-main sequence evolution. This mass loss will cause any surviving orbiting body to increase its semimajor axis and perhaps vary its eccentricity. Here, ... More
Dynamical evolution of an eccentric planet and a less massive debris discJun 27 2014We investigate the interaction between an eccentric planet and a less massive external debris disc. This scenario could occur after planet-planet scattering or merging events. We characterise the evolution over a wide range of initial conditions, using ... More
Collisional Evolution of Irregular Satellite Swarms: Detectable Dust around Solar System and Extrasolar PlanetsNov 22 2010Since the 1980's it has been becoming increasingly clear that the Solar System's irregular satellites are collisionally evolved. We derive a general model for the collisional evolution of an irregular satellite swarm and apply it to the Solar System and ... More
The bright end of the exo-Zodi luminosity function: Disk evolution and implications for exo-Earth detectabilityMay 28 2013Jun 09 2013We present the first characterisation of the 12um warm dust ("exo-Zodi") luminosity function around Sun-like stars, focussing on the dustiest systems that can be identified by WISE. We detect six new warm dust candidates, five of which have unknown ages. ... More
Dependence of a planet's chaotic zone on particle eccentricity: the shape of debris disc inner edgesOct 06 2011The orbit of a planet is surrounded by a chaotic zone wherein nearby particles' orbits are chaotic and unstable. Wisdom (1980) showed that the chaos is driven by the overlap of mean motion resonances which occurs within a distance (da/a)_chaos = 1.3 mu^2/7 ... More
A general model of resonance capture in planetary systems: First and second order resonancesDec 14 2010Mean motion resonances are a common feature of both our own Solar System and of extrasolar planetary systems. Bodies can be trapped in resonance when their orbital semi-major axes change, for instance when they migrate through a protoplanetary disc. We ... More
Insights into planet formation from debris disks: II. Giant impacts in extrasolar planetary systemsMar 15 2016Giant impacts refer to collisions between two objects each of which is massive enough to be considered at least a planetary embryo. The putative collision suffered by the proto-Earth that created the Moon is a prime example, though most Solar System bodies ... More
Do Two Temperature Debris Disks Have Multiple Belts?Aug 18 2014We present a study of debris disks whose spectra are well modelled by dust emission at two different temperatures. These disks are typically assumed to be a sign of multiple belts, which in only a few cases have been confirmed via high resolution observations. ... More
Debris from terrestrial planet formation: the Moon-forming collisionJun 19 2012We study the evolution of debris created in the giant impacts expected during the final stages of terrestrial planet formation. The starting point is the debris created in a simulation of the Moon-forming impact. The dynamical evolution is followed for ... More
Dynamical Constraints on Outer Planets in Super-Earth SystemsDec 17 2015This paper considers secular interactions within multi-planet systems. In particular we consider dynamical evolution of known planetary systems resulting from an additional hypothetical planet on an eccentric orbit. We start with an analytical study of ... More
Debris disk size distributions: steady state collisional evolution with P-R drag and other loss processesMar 28 2011We present a new scheme for determining the shape of the size distribution, and its evolution, for collisional cascades of planetesimals undergoing destructive collisions and loss processes like Poynting-Robertson drag. The scheme treats the steady state ... More
Resolved Imaging of the HD191089 Debris DiscAug 04 2010Aug 06 2010Two thirds of the F star members of the 12 Myr old Beta Pictoris Moving Group (BPMG) show significant excess emission in the mid-infrared, several million years after the expected dispersal of the protoplanetary disc. Theoretical models of planet formation ... More
Scattering of exocomets by a planet chain: exozodi levels and the delivery of cometary material to inner planetsJun 04 2018Exocomets scattered by planets have been invoked to explain observations in multiple contexts, including the frequently found near- and mid-infrared excess around nearby stars arising from exozodiacal dust. Here we investigate how the process of inward ... More
Outward Migration of Terrestrial Embryos in Binary SystemsSep 01 2009We consider the formation and migration of protoplanetary embryos in disks around the stars in tight binary systems (separations ~ 20 AU. In such systems, the initial stages of runaway embryo formation are expected to only take place within some critical ... More
Simulations of two-planet systems through all phases of stellar evolution: implications for the instability boundary and white dwarf pollutionFeb 14 2013Exoplanets have been observed at many stages of their host star's life, including the main sequence (MS), subgiant and red giant branch stages. Also, polluted white dwarfs (WDs) likely represent dynamically active systems at late times. Here, we perform ... More
Five steps in the evolution from protoplanetary to debris diskDec 17 2014The protoplanetary disks of Herbig Ae stars eventually dissipate leaving a tenuous debris disk comprised of planetesimals and dust, as well as possibly gas and planets. This paper uses the properties of 10-20Myr A star debris disks to consider the protoplanetary ... More
Oort cloud asteroids: Collisional evolution, the Nice Model, and the Grand TackMar 07 2019If the Solar system had a history of planet migration, the signature of that migration may be imprinted on the populations of asteroids and comets that were scattered in the planets' wake. Here, we consider the dynamical and collisional evolution of inner ... More
Debris from giant impacts between planetary embryos at large orbital radiiMar 07 2014We consider the observational signatures of giant impacts between planetary embryos. While the debris released in the impact remains in a clump for only a single orbit, there is a much longer lasting asymmetry caused by the fact that all debris must pass ... More
Imaged sub-stellar companions: not as eccentric as they appear? The effect of an unseen inner mass on derived orbitsOct 28 2013Increasing numbers of sub-stellar companions are now being discovered via direct imaging. Orbital elements for some of these objects have been derived using star--companion astrometry, and several of these appear to have eccentricities significantly greater ... More
Constraining the orbits of sub-stellar companions imaged over short orbital arcsFeb 06 2015Imaging a star's companion at multiple epochs over a short orbital arc provides only four of the six coordinates required for a unique orbital solution. Probability distributions of possible solutions are commonly generated by Monte Carlo (MCMC) analysis, ... More
Double-ringed debris discs could be the work of eccentric planets: explaining the strange morphology of HD 107146Jul 15 2015We investigate the general interaction between an eccentric planet and a coplanar debris disc of the same mass, using analytical theory and n-body simulations. Such an interaction could result from a planet-planet scattering or merging event. We show ... More
Post-Main Sequence Evolution of Debris DiscsDec 07 2010The population of debris discs on the main sequence is well constrained, however very little is known about debris discs around evolved stars. In this work we provide a theoretical framework that considers the effects of stellar evolution on debris discs; ... More
Hamiltonian model of capture into mean motion resonanceNov 22 2010Mean motion resonances are a common feature of both our own Solar System and of extrasolar planetary systems. Bodies can be trapped in resonance when their orbital semi-major axes change, for instance when they migrate through a protoplanetary disc. We ... More
Debris disc stirring by secular perturbations from giant planetsJul 08 2009Aug 13 2009Detectable debris discs are thought to require dynamical excitation (`stirring'), so that planetesimal collisions release large quantities of dust. We investigate the effects of the secular perturbations of a planet, which may lie at a significant distance ... More
The History of the Solar System's Debris Disc: Observable Properties of the Kuiper BeltJun 19 2009The Nice model of Gomes et al. (2005) suggests that the migration of the giant planets caused a planetesimal clearing event which led to the Late Heavy Bombardment (LHB) at 880 Myr. Here we investigate the IR emission from the Kuiper belt during the history ... More
How Common are Extrasolar, Late Heavy Bombardments?Nov 17 2009The habitability of planets is strongly affected by impacts from comets and asteroids. Indications from the ages of Moon rocks suggest that the inner Solar System experienced an increased rate of impacts roughly 3.8 Gya known as the Late Heavy Bombardment ... More
Dynamical Simulations of the Planetary System HD69830Dec 12 2008HD 69830 exhibits radial velocity variations attributed to three planets as well as infrared emission attributed to a warm debris disk. Previous studies have developed models for the planet migration and mass growth (Alibert et al. 2006) and the replenishment ... More
Observations, Modeling and Theory of Debris DisksJan 03 2014Mar 07 2014Main sequence stars, like the Sun, are often found to be orbited by circumstellar material that can be categorized into two groups, planets and debris. The latter is made up of asteroids and comets, as well as the dust and gas derived from them, which ... More
Resonant Trapping of Planetesimals by Planet Migration: Debris Disk Clumps and Vega's Similarity to the Solar SystemAug 14 2003This paper describes a model which can explain the observed clumpy structures of debris disks. Clumps arise because after a planetary system forms its planets migrate due to angular momentum exchange with the remaining planetesimals. Outward migration ... More
Dust in Resonant Extrasolar Kuiper Belts - Grain Size and Wavelength Dependence of Disk StructureNov 08 2005This paper considers the distribution of dust which originates in the break-up of planetesimals that are trapped in resonance with a planet. There are three grain populations with different spatial distributions: (I) large grains have the clumpy resonant ... More
A statistically significant lack of debris discs in medium separation binary systemsJul 10 2019We compile a sample of 341 binary and multiple star systems with the aim of searching for and characterising Kuiper belt-like debris discs. The sample is assembled by combining several smaller samples studied in previously published work with targets ... More
Transit Probabilities in Secularly Evolving Planetary SystemsMar 29 2017This paper considers whether the population of known transiting exoplanets provides evidence for additional outer planets on inclined orbits, due to the perturbing effect of such planets on the orbits of inner planets. As such, we develop a semi-analytical ... More
Using warm dust to constrain unseen planetsJul 30 2018Cold outer debris belts orbit a significant fraction of stars, many of which are planet-hosts. Radiative forces from the star lead to dust particles leaving the outer belts and spiralling inwards under Poynting-Robertson drag. We present an empirical ... More
The Great Escape III: Placing post-main-sequence evolution of planetary and binary systems in a Galactic contextOct 04 2013Our improving understanding of the life cycle of planetary systems prompts investigations of the role of the Galactic environment before, during and after Asymptotic Giant Branch (AGB) stellar evolution. Here, we investigate the interplay between stellar ... More
Cometary impactors on the TRAPPIST-1 planets can destroy all planetary atmospheres and rebuild secondary atmospheres on planets f, g, hFeb 14 2018Jul 03 2018The TRAPPIST-1 system is unique in that it has a chain of seven terrestrial Earth-like planets located close to or in its habitable zone. In this paper, we study the effect of potential cometary impacts on the TRAPPIST-1 planets and how they would affect ... More
Imaging [CI] around HD 131835: reinterpreting young debris discs with protoplanetary disc levels of CO gas as shielded secondary discsNov 20 2018Despite being $>10$Myr, there are $\sim$10 debris discs with as much CO gas as in protoplanetary discs. Such discs have been assumed to be "hybrid", i.e., with secondary dust but primordial gas. Here we show that both the dust and gas in such systems ... More
Dynamics of small bodies in planetary systemsJul 08 2008The number of stars that are known to have debris disks is greater than that of stars known to harbour planets. These disks are detected because dust is created in the destruction of planetesimals in the disks much in the same way that dust is produced ... More
Spiral Structure when Setting up Pericentre Glow: Possible Giant Planets at Hundreds of AU in the HD141569 DiskJun 09 2005This paper discusses the impact of introducing a planet on an eccentric orbit into a planetesimal disk. That planet's secular perturbations cause the orbits of the planetesimals to evolve in such a way that at any one time planetesimals at the same distance ... More
The Insignificance of P-R Drag in Detectable Extrasolar Planetesimal BeltsJan 04 2005This paper considers a simple model in which dust produced in a planetesimal belt migrates in toward the star due to P-R drag suffering destructive collisions with other dust grains on the way. Assuming the dust is all of the same size, the resulting ... More
The Great Escape: How Exoplanets and Smaller Bodies Desert Dying StarsJul 06 2011Mounting discoveries of extrasolar planets orbiting post-main sequence stars motivate studies aimed at understanding the fate of these planets. In the traditional "adiabatic" approximation, a secondary's eccentricity remains constant during stellar mass ... More
Searching for Saturn's Dust Swarm: Limits on the size distribution of Irregular Satellites from km to micron sizesJul 11 2011We describe a search for dust created in collisions between the Saturnian irregular satellites using archival \emph{Spitzer} MIPS observations. Although we detected a degree scale Saturn-centric excess that might be attributed to an irregular satellite ... More
Exoplanet recycling in massive white-dwarf debris discsMay 11 2018Several tens of white dwarfs are known to host circumstellar discs of dusty debris, thought to arise from the tidal disruption of rocky bodies originating in the star's remnant planetary system. This paper investigates the evolution of such discs if they ... More
ALMA observations of the narrow HR 4796A debris ringJan 16 2018The young A0V star HR 4796A is host to a bright and narrow ring of dust, thought to originate in collisions between planetesimals within a belt analogous to the Solar System's Edgeworth-Kuiper belt. Here we present high spatial resolution 880$\mu$m continuum ... More
Herschel Observations of Debris Discs Orbiting Planet-hosting SubgiantsNov 12 2013Debris discs are commonly detected orbiting main-sequence stars, yet little is known regarding their fate as the star evolves to become a giant. Recent observations of radial velocity detected planets orbiting giant stars highlight this population and ... More
Extra-Solar Kuiper Belt Dust DisksMar 15 2007The dust disks observed around mature stars are evidence that plantesimals are present in these systems on spatial scales that are similar to that of the asteroids and the KBOs in the Solar System. These dust disks (a.k.a. ``debris disks'') present a ... More
An automated search for transiting exocometsNov 07 2018This paper discusses an algorithm for detecting single transits in photometric time-series data. Specifically, we aim to identify asymmetric transits with ingress that is more rapid than egress, as expected for cometary bodies with a significant tail. ... More
A statistically significant lack of debris discs in medium separation binary systemsJul 10 2019Jul 11 2019We compile a sample of 341 binary and multiple star systems with the aim of searching for and characterising Kuiper belt-like debris discs. The sample is assembled by combining several smaller samples studied in previously published work with targets ... More
Resolved Imaging of the HR 8799 Debris Disk with HerschelNov 12 2013We present Herschel far-infrared and submillimeter maps of the debris disk associated with the HR 8799 planetary system. We resolve the outer disk emission at 70, 100, 160 and 250 um and detect the disk at 350 and 500 um. A smooth model explains the observed ... More
Capture and evolution of dust in planetary mean-motion resonances: a fast, semi-analytic method for generating resonantly trapped disk imagesJan 07 2015Dust grains migrating under Poynting-Robertson drag may be trapped in mean-motion resonances with planets. Such resonantly trapped grains are observed in the solar system. In extrasolar systems, the exozodiacal light produced by dust grains is expected ... More
IR-excesses around nearby Lambda Boo stars are caused by debris disks rather than ISM bow wavesNov 18 2015Lambda Boo stars are predominately A-type stars with solar abundant C, N, O, and S, but up to 2 dex underabundances of refractory elements. The stars' unusual surface abundances could be due to a selective accretion of volatile gas over dust. It has been ... More
Dynamical effects of stellar mass loss on a Kuiper-like beltFeb 15 2011Feb 17 2011A quarter of DA white dwarfs are metal polluted, yet elements heavier than helium sink down through the stellar atmosphere on timescales of days. Hence, these white dwarfs must be currently accreting material containing heavy elements. Here, we consider ... More
Circumstellar discs: What will be next?Mar 24 2017This prospective chapter gives our view on the evolution of the study of circumstellar discs within the next 20 years from both observational and theoretical sides. We first present the expected improvements in our knowledge of protoplanetary discs as ... More
Dancing with the Stars: Formation of the Fomalhaut triple system and its effect on the debris disksApr 28 2014Fomalhaut is a triple system, with all components widely separated (~1E5 au). Such widely separated binaries are thought to form during cluster dissolution, but that process is unlikely to form such a triple system. We explore an alternative scenario, ... More
The Numerical Simulation of Ship Waves Using Cartesian Grid Methods with Adaptive Mesh RefinementOct 07 2014Cartesian-grid methods with Adaptive Mesh Refinement (AMR) are ideally suited for simulating the breaking of waves, the formation of spray, and the entrainment of air around ships. As a result of the cartesian-grid formulation, minimal input is required ... More
Spatially Resolved Images of Dust Belt(s) Around the Planet-hosting Subgiant Kappa CrBFeb 27 2013Mar 08 2013We present Herschel spatially resolved images of the debris disc orbiting the subgiant Kappa CrB. Not only are these the first resolved images of a debris disc orbiting a subgiant, but Kappa CrB is a rare example of an intermediate mass star where a detailed ... More
Post-main sequence evolution of A star debris discsJul 26 2010Jul 27 2010While the population of main sequence debris discs is well constrained, little is known about debris discs around evolved stars. This paper provides a theoretical framework considering the effects of stellar evolution on debris discs, particularly the ... More
The scattering of small bodies in planetary systems: constraints on the possible orbits of cometary materialNov 08 2011The scattering of small bodies by planets is an important dynamical process in planetary systems. We present an analytical model to describe this process using the simplifying assumption that each particle's dynamics is dominated by a single planet at ... More
Warm dusty discs: Exploring the A star 24um debris populationApr 05 2010(Abridged) Studies of debris discs have shown that most systems are analogous to the EKB. In this study we aim to determine how many IRAS 25um excesses towards A stars are real, and investigate where the dust lies. We observe with TIMMI2, VISIR, Michelle ... More
New sub-millimeter limits on dust in the 55 Cancri planetary systemApr 08 2002We present new, high-sensitivity sub-millimeter observations towards 55 Cancri, a nearby G8 star with one, or possibly two, known planetary companion(s). Our 850 $\mu$m map, obtained with the SCUBA instrument on the James Clerk Maxwell Telescope, shows ... More
Kuiper Belt-Like Hot and Cold Populations of Planetesimal Inclinations in the $β$ Pictoris Belt Revealed by ALMAFeb 11 2019The inclination distribution of the Kuiper belt provides unique constraints on its origin and dynamical evolution, motivating vertically resolved observations of extrasolar planetesimal belts. We present ALMA observations of millimeter emission in the ... More
Debris disks as signposts of terrestrial planet formationMar 31 2011Circumstantial evidence suggests that most known extra-solar planetary systems are survivors of violent dynamical instabilities. Here we explore how giant planet instabilities affect the formation and survival of terrestrial planets. We simulate planetary ... More
Debris disks as signposts of terrestrial planet formation. II Dependence of exoplanet architectures on giant planet and disk propertiesJan 17 2012Feb 16 2012We present models for the formation of terrestrial planets, and the collisional evolution of debris disks, in planetary systems that contain multiple unstable gas giants. We previously showed that the dynamics of the giant planets introduces a correlation ... More
The debris disk - terrestrial planet connectionApr 14 2011The eccentric orbits of the known extrasolar giant planets provide evidence that most planet-forming environments undergo violent dynamical instabilities. Here, we numerically simulate the impact of giant planet instabilities on planetary systems as a ... More
Kuiper belt structure around nearby super-Earth host starsMar 06 2015We present new observations of the Kuiper belt analogues around HD 38858 and HD 20794, hosts of super-Earth mass planets within 1 au. As two of the four nearby G-type stars (with HD 69830 and 61 Vir) that form the basis of a possible correlation between ... More
Kuiper Belt Analogues in Nearby M-type Planet-host SystemsMar 07 2018We present the results of a Herschel survey of 21 late-type stars that host planets discovered by the radial velocity technique. The aims were to discover new disks in these systems and to search for any correlation between planet presence and disk properties. ... More
Debris discs and comet populations around Sun-like stars: the Solar System in contextJan 28 2010Numerous nearby FGK dwarfs possess discs of debris generated by collisions among comets. Here we fit the levels of dusty excess observed by Spitzer at 70$\umu$m and show that they form a rather smooth distribution. Taking into account the transition of ... More
The wavelength dependence of interstellar polarization in the Local Hot BubbleDec 02 2018The properties of dust in the interstellar medium (ISM) nearest the Sun are poorly understood because the low column densities of dust toward nearby stars induce little photometric reddening, rendering the grains largely undetectable. Stellar polarimetry ... More
Unlocking the secrets of the midplane gas and dust distribution in the young hybrid disc HD 141569May 07 2018Jun 21 2018HD141569 is a pre-main sequence star with a disc uniquely placed between protoplanetary and debris discs, similar to the older `hybrid' type discs. This work aims to place the mass and spatial structure of the disc midplane in the context of the debris, ... More
Confusion limited surveys: using WISE to quantify the rarity of warm dust around Kepler starsJul 02 2012We describe a search for infra-red excess emission from dusty circumstellar material around 180,000 stars observed by the Kepler and WISE missions. This study is motivated by i) the potential to find bright warm disks around planet host stars, ii) a need ... More
Collisional Processes in Extrasolar Planetsimal Disks - Dust Clumps in Fomalhaut's Debris DiskApr 02 2002This paper presents a model for the outcome of collisions between planetesimals in a debris disk and assesses the impact of collisional processes on the structure and size distribution of the disk. The model is presented by its application to Fomalhaut's ... More
Spelling Rules for the Monster/Semple TowerJul 07 2014We further study the incidence relations that arise from the various subtowers, known as Baby Monster, which exist within the $\mathbb{R}^{3}$-Monster Tower. This allows us to complete the $RVT$ class spelling rules. We also present a method of calculating ... More
The Debris Disk Explorer: a balloon-borne coronagraph for observing debris disksSep 18 2013The Debris Disk Explorer (DDX) is a proposed balloon-borne investigation of debris disks around nearby stars. Debris disks are analogs of the Asteroid Belt (mainly rocky) and Kuiper Belt (mainly icy) in our Solar System. DDX will measure the size, shape, ... More
A Monster Tower Approach to Goursat Multi-FlagsJul 21 2011We consider here the problem of classifying orbits of an action of the dif- feomorphism group of 3-space on a tower of fibrations with P2-fibers that generalize the Monster Tower due to Montgomery and Zhitomirskii. As a corollary we give the first steps ... More
Are debris disks self-stirred?Feb 18 2010This paper considers the evidence that debris disks are self-stirred by the formation of Plutos. A model for the dust produced during self-stirring is applied to statistics for A stars. As there is no significant difference between excesses of A-stars ... More
Eight billion asteroids in the Oort cloudOct 27 2014The Oort cloud is usually thought of as a collection of icy comets inhabiting the outer reaches of the Solar system, but this picture is incomplete. We use simulations of the formation of the Oort cloud to show that ~4% of the small bodies in the Oort ... More
A circumbinary protoplanetary disc in a polar configurationJan 15 2019Nearly all young stars are initially surrounded by `protoplanetary' discs of gas and dust, and in the case of single stars at least 30\% of these discs go on to form planets. The process of protoplanetary disc formation can result in initial misalignments, ... More
The Inner Disk Structure, Disk-Planet Interactions, and Temporal Evolution in the Beta Pictoris System: A Two-Epoch HST/STIS Coronagraphic StudyJan 13 2015We present deep HST/STIS coronagraphic images of the Beta Pic debris disk obtained at two epochs separated by 15 years. The new images and the re-reduction of the 1997 data provide the most sensitive and detailed views of the disk at optical wavelengths ... More
The Numerical Simulation of Ship Waves Using Cartesian-Grid and Volume-of-Fluid MethodsOct 07 2014Cartesian-grid methods in combination with immersed-body and volume-of-fluid methods are ideally suited for simulating breaking waves around ships. A surface panelization of the ship hull is used as input to impose body-boundary conditions on a three-dimensional ... More
Resolved Debris Discs Around A Stars in the Herschel DEBRIS SurveyOct 01 2012The majority of debris discs discovered so far have only been detected through infrared excess emission above stellar photospheres. While disc properties can be inferred from unresolved photometry alone under various assumptions for the physical properties ... More
The Northern Arc of $ε$ Eridani's Debris Ring as Seen by ALMAMay 03 2017Jun 07 2017We present the first ALMA observations of the closest known extrasolar debris disc. This disc orbits the star $\epsilon$ Eridani, a K-type star just 3.2pc away. Due to the proximity of the star, the entire disc cannot fit within the ALMA field of view. ... More
Mass and Temperature of the TWA 7 Debris DiskApr 03 2007We present photometric detections of dust emission at 850 and 450 micron around the pre-main sequence M1 dwarf TWA 7 using the SCUBA camera on the James Clerk Maxwell Telescope. These data confirm the presence of a cold dust disk around TWA 7, a member ... More
Resolving the terrestrial planet forming regions of HD113766 and HD172555 with MIDIFeb 24 2012We present new MIDI interferometric and VISIR spectroscopic observations of HD113766 and HD172555. Additionally we present VISIR 11um and 18um imaging observations of HD113766. These sources represent the youngest (16Myr and 12Myr old respectively) debris ... More
Resolving the hot dust around HD69830 and eta Corvi with MIDI and VISIRJun 19 2009Most of the known debris discs exhibit cool dust in regions analogous to the Edgeworth-Kuiper Belt. However, a rare subset show hot excess from within a few AU, which is often inferred to be transient. We examine 2 such sources to place limits on their ... More
Origin of the Metallicity Dependence of Exoplanet Host Stars in the Protoplanetary Disk Mass DistributionJul 18 2007The probability of a star hosting a planet that is detectable in radial velocity surveys increases Ppl(Z) oc 10^2Z, where Z is metallicity. Core accretion models reproduce this trend, since the protoplanetary disk of a high metallicity star has a high ... More
Stochastic accretion of planetesimals onto white dwarfs: constraints on the mass distribution of accreted material from atmospheric pollutionJan 23 2014This paper explores how the stochastic accretion of planetesimals onto white dwarfs would be manifested in observations of their atmospheric pollution. Archival observations of pollution levels for unbiased samples of DA and non-DA white dwarfs are used ... More
Uniqueness of Bohmian Mechanics, and Solutions From Probability ConservationOct 22 2007We show that one-dimensional Bohmian mechanics is unique, in that, the Bohm trajectories are the only solutions that conserve total left (or right) probability. In Brandt et al., Phys. Lett. A, 249 (1998) 265--270, they define quantile motion--unique ... More
Debris discs around nearby Solar analoguesJul 21 2009An unbiased search for debris discs around nearby Sun-like stars is reported. Thirteen G-dwarfs at 12-15 parsecs distance were searched at 850 $\umu$m wavelength, and a disc is confirmed around HD 30495. The estimated dust mass is 0.008 M$_{\oplus}$ with ... More
The nature of mid-infrared excesses from hot dust around Sun-like starsApr 29 2008(ABRIDGED) Studies of debris disks have shown that most systems are analogous to the Edgeworth-Kuiper Belt. However a rare subset of sun-like stars possess dust which lies in the terrestrial planet region. In this study we aim to determine how many sources ... More
Sub-mm observations and modelling of Vega type starsNov 26 2003Dec 10 2003We present new sub-mm observations and modelling of Vega excess stars, using realistic dust grain models. For resolved disks, we find that different objects require very different dust grain properties in order to simultaneously fit the image data and ... More
Steady-state evolution of debris disks around solar-type starsFeb 21 2011We present an analysis of debris disk data around Solar-type stars (spectral types F0-K5) using the steady-state analytical model of Wyatt et al. (2007). Models are fitted to published data from the FEPS (Meyer et al. 2006) project and various GTO programs ... More
Monte Carlo Generation of Bohmian TrajectoriesJul 01 2008We report on a Monte Carlo method that generates one-dimensional trajectories for Bohm's formulation of quantum mechanics that doesn't involve differentiation or integration of any equations of motion. At each time, t=n\delta t (n=1,2,3,...), N particle ... More
SCUBA Observations of Dust around Lindroos Stars: Evidence for a Substantial Submillimetre Disc PopulationMar 05 2003We have observed 22 Lindroos stars with SCUBA on the JCMT to search for evidence of dust discs. Stars in this sample are the less massive companions of B-type primaries and have ages of 10-170Myr. Dust was detected around three of these stars (HD74067, ... More
Extinction and the Dimming of KIC 8462852Aug 24 2017Sep 01 2017To test alternative hypotheses for the behavior of KIC 8462852, we obtained measurements of the star over a wide wavelength range from the UV to the mid-infrared from October 2015 through December 2016, using Swift, Spitzer and at AstroLAB IRIS. The star ... More
Asymmetric Heating of the HR 4796A Dust Ring Due to Pericenter GlowNov 05 2010We have obtained new resolved images of the well-studied HR 4796A dust ring at 18 and 25 microns with the 8-meter Gemini telescopes. These images confirm the previously observed spatial extent seen in mid-IR, near-IR, and optical images of the source. ... More
A self-consistent model for the evolution of the gas produced in the debris disc of $β$ PictorisJun 03 2016This paper presents a self-consistent model for the evolution of gas produced in the debris disc of $\beta$ Pictoris. Our model proposes that atomic carbon and oxygen are created from the photodissociation of CO, which is itself released from volatile-rich ... More
Science with an ngVLA: Debris disk structure and compositionOct 15 2018Debris disks, comprised of planetsimal belts and the dust and gas produced by their mutual collisions, are the longest-lived phase of circumstellar disks. Typically much fainter in emission than protoplanetary disks, debris disks can be found in associations ... More
The REASONS Survey: Resolved Millimeter Observations of a Large Debris Disk Around the Nearby F Star HD 170773Jun 20 2019Debris disks are extrasolar analogs to our own Kuiper Belt and they are detected around at least 17% of nearby Sun-like stars. The morphology and dynamics of a disk encode information about its history, as well as that of any exoplanets within the system. ... More
The Weak Null Condition and Kaluza-Klein SpacetimesMay 31 2017In this paper we prove the non-linear stability of a system of non-linear wave equations satisfying the weak null condition. In particular, this includes the case of the non-linear stability of Minkowski spacetime times a $d$-torus subject to perturbations ... More
The debris disk around gamma Doradus resolved with HerschelDec 06 2012We present observations of the debris disk around gamma Doradus, an F1V star, from the Herschel Key Programme DEBRIS (Disc Emission via Bias-free Reconnaissance in the Infrared/Submillimetre). The disk is well-resolved at 70, 100 and 160 micron, resolved ... More