On the Dynamics of the Jovian Ionosphere and Thermosphere: II. The Measurement of H3 Vibrational Temperature, Column Density, and Total Emission

We present the first reported measurements of the intensity of a “hotband” transition for the H₃⁺ molecular ion in the northern auroral/polar region of Jupiter. This transition is identified as the R(3, 4⁺) line of the (2v₂(l=0)→v₂) hotband, with a wavelength of 3.94895 μm. This is the first time such a transition has been measured outside the laboratory, and the wavelength as measured on Jupiter is within the experimental accuracy of the lab measurement. This detection makes it possible to investigate H₃⁺ transitions that simultaneously originate from different vibrational levels. We use the intensity ratio between this line and the Q(1, 0⁻) fundamental transition to derive effective vibrational temperatures, column densities, and total emission parameters as a function of position across the auroral/polar region. Effective temperatures range from ∼900 to ∼1250 K; an increase in average temperature during our observing run of ∼100 K is noted. The derived temperatures are toward the high end or in excess of the auroral temperature range that has been reported in the literature to date. The relationship among emission intensity, temperature, and density is shown to be complex. This may reflect the nonthermalization of the vibrational levels at the gas densities prevailing in the jovian thermosphere. An alternative analysis allowing for this effect is presented. But this approach requires thermospheric temperatures to be ∼1500 K at the level that the majority of H₃⁺ is being produced, higher than has previously been proposed.     

A Global Solution for the Gravity Field, Rotation, Landmarks, and Ephemeris of Eros

As part of the NEAR Radio Science investigation, a global solution that includes both spherical and ellipsoidal harmonic gravity fields of Eros, Eros pole and rotation rate, Eros ephemeris, and landmark positions from the optical data was generated. This solution uses the entire one-year in orbit collection of X-band radiometric tracking (Doppler and range) from the Deep Space Network and landmark tracking observations generated from the NEAR spacecraft images of Eros. When compared to a constant density shape model, the gravity field shows a nearly homogeneous Eros. The Eros landmark solutions are in good agreement with the Eros shape model, and they reduce the center-of-mass and center-of-figure offset in the z direction to 13 m. Most of the NEAR spacecraft orbits are determined in all directions to an accuracy of several meters. The solution for the ephemeris of Eros constrains the mass of Vesta to 18.2±0.4 km³/s² and reduces the uncertainty in the Earth-Moon mass ratio.     

Hydrogeological research: just getting started

This paper comments on the current state of knowledge in the field of hydrogeology and claims that fundamental understandings must be developed if creative research is to have maximum impact. Problems of great importance to society include water development and quality, waste disposal, and global cycling of resources. These problems cannot be addressed effectively unless significant advances are made in understanding of a range of challenging scientific issues including fundamental physics, the importance of scale, modeling, and chemical and biological processes. Meaningful advances in hydrogeologic research will require an increased emphasis on fundamental understanding, interdisciplinary approaches, educational reforms, and the attraction of excellent researchers to the field.     

Chlorohydrocarbon pesticides in the Australian marine environment after banning in the period from the 1970s to 1980s

The chlorohydrocarbon pesticides (CHPs) (principally DDT, dieldrin, hexachlorocyclohexane (HCH) including lindane, chlordane, heptachlor and heptachlorepoxide, aldrin and hexachlorobenzene (HCB)) were used extensively in Australia during the 1960s and 1970s. These were progressively banned from the 1970s with DDT being totally banned in 1987. The levels in marine waters are believed to have progressively declined as indicated by water in the Brisbane River, which consistently fell from maximum concentrations of about 1.7 μg/l in 1972–1973 to not detectable in 1986–1987. In some urban areas sediment concentrations, up to 1700 μg/kg dry weight, were recorded in the early 1990s which may reflect the reworking and exposure of older more contaminated material. Fish exhibited consistent occurrence of DDT, HCH, dieldrin and HCB through the 1970s to the 1990s. Maximum concentrations of DDT and dieldrin occurred generally in the 1970s at 40.3 and 8.8 μg/g wet weight, and minimums in the 1990s at 2.4 and 0.041 μg/g wet weight respectively. Inputs of dialdrin from sewage and DDT from the broad environment, reflected by the calculated daily human uptake in the diet, were shown to decline with half-lives of 1.1–1.5 and about 3 years respectively. This evidence suggests that banning of the CHPs has greatly reduced the inputs into the marine environment with consequent reductions in concentrations in biota but there is the occasional occurrence of relatively high concentrations.     

The host galaxies of luminous radio-quiet quasars

We present the results of a deep K -band imaging study which reveals the host galaxies around a sample of luminous radio-quiet quasars. The K -band images, obtained at UKIRT, are of sufficient quality to allow accurate modelling of the underlying host galaxy. Initially, the basic structure of the hosts is revealed using a modified clean deconvolution routine optimized for this analysis. Two of the 14 quasars are shown to have host galaxies with violently disturbed morphologies which cannot be modelled by smooth elliptical profiles. For the remainder of our sample, 2D models of the host and nuclear component are fitted to the images using the χ ² statistic to determine goodness of fit. Host galaxies are detected around all of the quasars. The reliability of the modelling is extensively tested, and we find the host luminosity to be well constrained for nine quasars. The derived average K -band absolute K -corrected host galaxy magnitude for these luminous radio-quiet quasars is 〈 M _K 〉=25.15±0.04, slightly more luminous than an L * galaxy. The spread of derived host galaxy luminosities is small, although the spread of nuclear-to-host ratios is not. These host luminosities are shown to be comparable to those derived from samples of quasars of lower total luminosity, and we conclude that there is no correlation between host and nuclear luminosity for these quasars. Nuclear-to-host ratios break the lower limit previously suggested from studies of lower nuclear luminosity quasars and Seyfert galaxies. Morphologies are less certain but, on the scales probed by these images, some hosts appear to be dominated by spheroids while others appear to have disc-dominated profiles.     

Bayesian galaxy shape measurement for weak lensing surveys – I. Methodology and a fast-fitting algorithm

The principles of measuring the shapes of galaxies by a model-fitting approach are discussed in the context of shape measurement for surveys of weak gravitational lensing. It is argued that such an approach should be optimal, allowing measurement with maximal signal-to-noise ratio, coupled with estimation of measurement errors. The distinction between likelihood-based and Bayesian methods is discussed. Systematic biases in the Bayesian method may be evaluated as part of the fitting process, and overall such an approach should yield unbiased shear estimation without requiring external calibration from simulations. The principal disadvantage of model fitting for large surveys is the computational time required, but here an algorithm is presented that enables large surveys to be analysed in feasible computation times. The method and algorithm is tested on simulated galaxies from the Shear TEsting Programme (STEP).     

Australites from Northern Australia

Abstract— Abundant tektites have been found in buried alluvial gravels at the south end of Lake Argyle in far northern Australia. The recovered tektites are unusual in that an astounding number are very large and 75% of those analyzed to date are HMg tektites, heretofore a very rare type in Australia. It is now clear that the paucity of tektites in northern Australia is due to the former high energy erosional environment rather than to crossing the strewnfield boundary, as has been previously suggested. The N-S extent of the australite strewnfield encompasses the entire continent.