A5001299724- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Planetary Science and Exploration
- Scientific Research and Discoveries
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Geology and Paleoclimatology Research
- Numerical methods for differential equations
- Space Exploration and Technology
- Adaptive optics and wavefront sensing
- Galaxies: Formation, Evolution, Phenomena
- Methane Hydrates and Related Phenomena
- Cosmology and Gravitation Theories
- Molecular Spectroscopy and Structure
- Geophysics and Gravity Measurements
- Cyclone Separators and Fluid Dynamics
- Theoretical and Computational Physics
- Modeling and Simulation Systems
- Climate variability and models
- Gas Dynamics and Kinetic Theory
- Particle Dynamics in Fluid Flows
- Relativity and Gravitational Theory
- Simulation Techniques and Applications
University of Hong Kong
2015-2024
Chinese University of Hong Kong
2012-2023
University of California, Santa Barbara
1996-2009
Quality Research
2005
University of California, Berkeley
1998
Queen's University
1996-1998
Princeton University
1989-1991
We present a new symplectic algorithm that has the desirable properties of sophisticated but highly efficient numerical algorithms known as mixed variable (MVS) methods and that, in addition, can handle close encounters between objects. This technique is based on variant standard MVS methods, it handles by employing multiple time step technique. When bodies are well separated, speed whenever two suffer mutual encounter, for relevant recursively subdivided to whatever level required....
The discovery by Marcy and coworkers of two planets in 2 : 1 orbital resonance about the star GJ 876 has been supplemented a dynamical fit to data Laughlin & Chambers, which places coplanar orbits deep three resonances at mean-motion commensurability. selection this almost singular state means that are certainly real, with small amplitudes libration variables, indefinitely stable. Several unusual properties revealed system. both lowest order variables secular variable, θ1 = λ1 - 2λ2 + ϖ1, θ2...
We consider the dynamical evolution of bound, hierarchical triples supermassive black holes that might be formed in nuclei galaxies undergoing sequential mergers. The tidal force outer hole on inner binary produces eccentricity oscillations through Kozai mechanism, and this can substantially reduce gravitational wave merger time binary. numerically calculate for a wide range initial conditions mass ratios, including effects octupole interactions triple as well general relativistic periastron...
The aerosolization and collection of submicrometre ultrafine virus particles were studied with the objective developing robust accurate methodologies to study airborne viruses.The efficiencies three sampling devices used sample biological - All Glass Impinger 30, SKC BioSampler a frit bubbler evaluated for particles. Test aerosol produced by atomizing suspensions single-stranded RNA double-stranded DNA bacteriophages. Size distribution results show that fraction viruses present in typical...
(Abridged) We investigate the dynamical evolution of coplanar hierarchical two-planet systems where ratio orbital semimajor axes alpha=a_1/a_2 is small. The parameters obtained from a multiple Kepler fit to radial velocity variations star are best interpreted as Jacobi coordinates and should be used in any analyses planetary systems. An approximate theory that can applied with wide range masses m_j eccentricities e_j octupole-level secular perturbation (OSPT). OSPT shows if maximum angular...
We present an updated analysis of radial velocity data the HD 82943 planetary system based on 10 years measurements obtained with Keck telescope. Previous studies have shown that has two planets are likely in 2:1 mean-motion resonance (MMR), orbital periods about 220 and 440 days (Lee et al. 2006). However, alternative fits qualitatively different also been suggested, a 1:1 (Gozdziewski & Konacki 2006) or three Laplace 4:2:1 (Beauge 2008). Here we use \c{hi}2 minimization combined parameter...
TOI-2525 is a K-type star with an estimated mass of M = 0.849$_{-0.033}^{+0.024}$ M$_\odot$ and radius R 0.785$_{-0.007}^{+0.007}$ R$_\odot$ observed by the TESS mission in 22 sectors (within 1 39). The light curves yield significant transit events two companions, which show strong timing variations (TTVs) semi-amplitude $\sim$6 hours. We performed TTV dynamical, photo-dynamical curve analysis data, combined radial velocity (RV) measurements from FEROS PFS, we confirmed planetary nature...
Understanding the origin of orbital resonances Galilean satellites Jupiter will constrain longevity extensive volcanism on Io, may explain a liquid ocean Europa, and guide studies dissipative properties stars Jupiter-like planets. The differential migration newly formed due to interactions with circumjovian disk can lead primordial formation Laplace relation n(1) - 3n(2) + 2n(3) = 0, where n(i) are mean angular velocities Ganymede, respectively. This contrasts by expansion orbits from tidal...
The two planets about the star GJ 876 appear to have undergone extensive migration from their point of origin in protoplanetary disk – both because close proximity (30 and 60 day orbital periods) occupying three stable resonances at 2:1 mean-motion commensurability. were most likely established by converging differential leading capture into resonances. A problem with this scenario is that continued system while it trapped leads eccentricities rapidly exceed observational upper limits . As...
The multiple-planet systems discovered by the Kepler mission show an excess of planet pairs with period ratios just wide exact commensurability for first-order resonances like 2:1 and 3:2. In principle, these could have both resonance angles associated librating if orbital eccentricities are sufficiently small, because width diverges in limit vanishingly small eccentricity. We consider a widely held scenario which planets were captured into migration due to planet–disk interactions,...
Three transiting circumbinary planets (Kepler-16 b, Kepler-34 and Kepler-35 b) have recently been discovered from photometric data taken by the Kepler spacecraft. Their orbits are significantly non-Keplerian because of large secondary-to-primary mass ratio orbital eccentricity binaries, as well proximity to binaries. We present an analytic theory, with planet treated a test particle, which shows that planetary motion can be represented superposition circular guiding center, forced...
Context . Prevailing N -body planet formation models typically start with lunar-mass embryos and show a general trend of rapid migration massive planetary cores to the inner Solar System in absence trap. This setup cannot capture evolution from planetesimal embryo, which is crucial final architecture system. Aims We aim model starting planetesimals ~10 −6 −10 −4 M ⊕ reproduce giant planets System. Methods simulated population 1000-5000 smooth protoplanetary disc, was evolved under effects...
Abstract An increasing number of compact planetary systems with multiple planets in a resonant chain have been detected. The must be maintained by convergent migration the due to planet–disk interactions if it is formed before dispersal protoplanetary gas disk. For type I an adiabatic disk, we show that analytic criterion for can developed requiring any part should convergently migrating toward remaining part. depends primarily on logarithmic gradients α and β surface density temperature...
A diversity of 2 : 1 resonance configurations can be expected in extrasolar planetary systems, and their geometry provide information about the origin resonances. Assembly during planet formation by differential migration planets due to planet-disk interaction is one scenario for mean-motion resonances systems. The stable that reached with constant masses initially coplanar nearly circular orbits are (1) antisymmetric variables θ1 = λ1 - 2λ2 + ϖ1 θ2 ϖ2 (where λj ϖj mean longitudes periapse,...
We present the results of a systematic survey numerical solutions to coagulation equation for rate coefficient form Aij ∝ (iμ jν + iν jμ) and monodisperse initial conditions. The confirm that there are three classes coefficients with qualitatively different solutions. For ν ≤ 1 λ = μ 1, solution evolves in an orderly fashion tends towards self-similar at large time t. properties scaling limit agree analytic predictions van Dongen Ernst. In particular, subset > 0 < we disagree Krivitsky find...
We present an analysis of the HD 82943 planetary system based on a radial velocity data set that combines new measurements obtained with Keck telescope and CORALIE published in graphical form. examine simultaneously goodness fit dynamical properties best-fit double-Keplerian model as function poorly constrained eccentricity argument periapse outer planet's orbit. The minimum chi_{nu}^2 is dynamically unstable if orbits are assumed to be coplanar. However, relatively shallow, there wide range...
view Abstract Citations (64) References (63) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS N-Body Evolution of Dense Clusters Compact Stars Lee, Man Hoi The dynamical evolution dense clusters compact stars is studied using direct N-body simulations. formation binaries and their subsequent merging by gravitational radiation emission important to the such clusters. Aarseth's NBODY5 simulation code modified include lowest order force during two-body encounters...
We report the discovery of a new planetary system around K giant $\eta$ Cet (HIP 5364, HD 6805) based on 118 high-precision optical radial velocities taken at Lick Observatory since July 2000. Since October 2011 an additional nine near-infrared Doppler measurements have been using ESO CRIRES spectrograph (VLT, UT1). The visible data set shows two clear periodicities. Although we cannot completely rule out that shorter period is due to rotational modulation stellar features, infrared show...
The nearby ultra-compact multiplanetary system YZ Ceti consists of at least three planets. orbital period each planet is the subject discussion in literature due to strong aliasing radial velocity data. stellar activity this M dwarf also hampers significantly derivation planetary parameters. With an additional 229 measurements obtained since discovery publication, we reanalyze and resolve alias issues. We use model comparison framework Bayesian statistics periodogram simulations based on a...