Water Ice in 2060 Chiron and its Implications for Centaurs and Kuiper Belt Objects

We report the detection of water ice in the Centaur 2060 Chiron, based on near-infrared spectra (1.0 - 2.5 micron) taken with the 3.8-meter United Kingdom Infrared Telescope (UKIRT) and the 10-meter Keck Telescope. The appearance of this ice is correlated with the recent decline in Chiron's cometary activity: the decrease in the coma cross-section allows previously hidden solid-state surface features to be seen. We predict that water ice is ubiquitous among Centaurs and Kuiper Belt objects, but its surface coverage varies from object to object, and thus determines its detectability and the occurrence of cometary activity.Comment: 18 pages, 3 figures, accepted by ApJ Letter

Population of the Scattered Kuiper Belt

We present the discovery of three new Scattered Kuiper Belt Objects (SKBOs) from a wide-field survey of the ecliptic. This continuing survey has to date covered 20.2 square degrees to a limiting red magnitude of 23.6. We combine the data from this new survey with an existing survey conducted at the University of Hawaii 2.2m telescope to constrain the number and mass of the SKBOs. The SKBOs are characterized by large eccentricities, perihelia near 35 AU, and semi-major axes > 50 AU. Using a maximum-likelihood model, we estimate the total number of SKBOs larger than 100 km in diameter to be N = 3.1 (+1.9/-1.3) x 10^4 (1 sigma) and the total mass of SKBOs to be about 0.05 Earth masses, demonstrating that the SKBOs are similar in number and mass to the Kuiper Belt inside 50 AU.Comment: 15 pages, 3 figure

Ellipsoidal Janus Nanoparticles Assembled at Spherical Oil/Water Interfaces

The equilibrium behavior of ellipsoidal Janus nanoparticles adsorbed at spherical oil/water interfaces was investigated using dissipative particle dynamics simulations. Several phenomena were documented that were not observed on similar simulations for planar oil/water interfaces. The nanoparticles were found to yield isotropic, radial nematic phases, and axial nematic domains, depending on the nanoparticle characteristics (aspect ratio and surface chemistry), particle density at the interface, and droplet properties (curvature of the interface, and surprisingly, liquid type). When adsorbed on water droplets, the nanoparticles with high aspect ratio and few nonpolar beads on their surface can show two preferred orientation angles. Only one equilibrium orientation was found for such nanoparticles adsorbed on oil droplets. These observations might help explain a discrepancy previously reported between experimental and simulation results concerning the preferential orientation of particles at liquid–liquid interfaces. Different driving forces are responsible for the phenomena just summarized, including nanoparticle–nanoparticle and nanoparticle–solvent interactions, nanoparticle density at the interface, and droplet curvature via the Laplace pressure. The simulation results we present could be useful for engineering Pickering emulsions toward practical applications, and perhaps also for guiding new technologies for material synthesis

Population and Size Distribution of Small Jovian Trojan Asteroids

We present a study of Jovian Trojan objects detected serendipitously during the course of a sky survey conducted at the University of Hawaii 2.2-meter telescope. We used a 8192 x 8192 pixel charge-coupled device (CCD) mosaic to observe 20 deg^2 at locations spread over the L4 Lagrangian swarm and reached a limiting magnitude V = 22.5 mag (50% of maximum detection efficiency). Ninety-three Jovian Trojans were detected with radii 2 - 20 km (assumed albedo 0.04). Their differential magnitude distribution has a slope of 0.40 +/- 0.05 corresponding to a power law size distribution index 3.0 +/- 0.3 (1-sigma). The total number of L4 Trojans with radii > 1 km is of order 1.6 x 10^5 and their combined mass (dominated by the largest objects) is ~ 10^{-4} M_{Earth}. The bias-corrected mean inclination is 13.7 +/- 0.5 deg. We also discuss the size and spatial distribution of the L4 swarm.Comment: 21 pages, 11 figures. AJ, in pres

The K+K+ Scattering Length from Lattice QCD

The K+K+ scattering length is calculated in fully-dynamical lattice QCD with domain-wall valence quarks on the MILC asqtad-improved gauge configurations with rooted staggered sea quarks. Three-flavor mixed-action chiral perturbation theory at next-to-leading order, which includes the leading effects of the finite lattice spacing, is used to extrapolate the results of the lattice calculation to the physical value of m_{K+}/f_{K+}. We find m_{K+} a_{K+K+} = -0.352 +- 0.016, where the statistical and systematic errors have been combined in quadrature.Comment: 17 pages, 12 figures. NPLQCD collaboratio

Properties of the Trans-Neptunian Belt: Statistics From the CFHT Survey

We present the results of a wide-field survey designed to measure the size, inclination, and radial distributions of Kuiper Belt Objects (KBOs). The survey found 86 KBOs in 73 square degrees observed to limiting red magnitude 23.7 using the Canada-France-Hawaii Telescope and the 12k x 8k CCD Mosaic camera. For the first time, both ecliptic and off-ecliptic fields were examined to more accurately constrain the inclination distribution of the KBOs. The survey data were processed using an automatic moving object detection algorithm, allowing a careful characterization of the biases involved. In this work, we quantify fundamental parameters of the Classical KBOs (CKBOs), the most numerous objects found in our sample, using the new data and a maximum likelihood simulation. Deriving results from our best-fit model, we find that the size distribution follows a differential power law with exponent q = 4.0 (+0.6)(-0.5) (1 sigma, or 68.27% confidence). In addition, the CKBOs inhabit a very thick disk consistent with a Gaussian distribution of inclinations with a Half-Width of i(1/2) = 20 (+6)(-4) deg (1 sigma). We estimate that there are N = 3.8 (+2.0)(-1.5) x 10^4 (1 sigma) CKBOs larger than 100 km in diameter. We also find compelling evidence for an outer edge to the CKBOs at heliocentric distance R = 50 AU.Comment: To be published in the Astronomical Journal, July 200

Precise Determination of the I=2 pipi Scattering Length from Mixed-Action Lattice QCD

The I=2 pipi scattering length is calculated in fully-dynamical lattice QCD with domain-wall valence quarks on the asqtad-improved coarse MILC configurations (with fourth-rooted staggered sea quarks) at four light-quark masses. Two- and three-flavor mixed-action chiral perturbation theory at next-to-leading order is used to perform the chiral and continuum extrapolations. At the physical charged pion mass, we find m_pi a_pipi(I=2) = -0.04330 +- 0.00042, where the error bar combines the statistical and systematic uncertainties in quadrature.Comment: 20 pages, 7 figure

Enhancing Optical Up-Conversion Through Electrodynamic Coupling with Ancillary Chromophores

In lanthanide-based optical materials, control over the relevant operating characteristics–for example transmission wavelength, phase and quantum efficiency–is generally achieved through the modification of parameters such as dopant/host combination, chromophore concentration and lattice structure. An alternative avenue for the control of optical response is through the introduction of secondary, codoped chromophores. Here, such secondary centers act as mediators, commonly bridging the transfer of energy between primary absorbers of externally sourced optical input and other sites of frequency-converted emission. Utilizing theoretical models based on experimentally feasible, three-dimensional crystal lattice structures; a fully quantized theoretical framework provides insights into the locally modified mechanisms that can be implemented within such systems. This leads to a discussion of how such effects might be deployed to either enhance, or potentially diminish, the efficiency of frequency up-conversion