Western Australia: the resource state

This paper examines the strength of Western Australia's claim to be ‘the resource state’. It traces the history of the state's mineral development and points to close links between the development, the growth of the economy and the spread of settlement. The crucial role of the state government in facilitating capital investment and fostering a growth ideology is also highlighted. The paper argues that while resource development and capital investment have brought tangible economic benefits to Western Australia and the nation, certain costs have also been generated. Growth has caused damage to the physical environment and the once‐numerous Aboriginal population. Moreover, given the international commodity crisis of the 1980s, mineral export strength is no sure recipe for economic success.     

The unified model and the Seyfert 2 infrared dichotomy

We present X-ray imaging spectroscopy of the extremely luminous infrared galaxy IRAS 09104+4109     obtained with the Chandra X-ray Observatory. With the arcsec resolution of Chandra , an unresolved source at the nucleus is separated from the surrounding cluster emission. A strong iron K line at 6.4 keV on a very hard continuum is detected from the nuclear source, rendering IRAS 09104+4109 the most distant reflection-dominated X-ray source known. Combined with the BeppoSAX detection of the excess hard X-ray emission, it provides further strong support for the presence of a hidden X-ray source of quasar luminosity in this infrared galaxy. Also seen is a faint linear structure to the north, which coincides with the main radio jet. An X-ray deficit in the corresponding region suggests an interaction between the cluster medium and the jet driven by the active nucleus.     

Mineralogy and petrography of amoeboid olivine aggregates from the reduced CV3 chondrites Efremovka,Leoville and Vigarano: Products of nebular condensation,accretion and annealing

Abstract— Amoeboid olivine aggregates (AOAs) from the reduced CV chondrites Efremovka, Leoville and Vigarano are irregularly‐shaped objects, up to 5 mm in size, composed of forsteritic olivine (Fa_<10) and a refractory, Ca, Al‐rich component. The AOAs are depleted in moderately volatile elements (Mn, Cr, Na, K), Fe, Ni‐metal and sulfides and contain no low‐Ca pyroxene. The refractory component consists of fine‐grained calcium‐aluminum‐rich inclusions (CAIs) composed of Al‐diopside, anorthite (An₁₀₀), and magnesium‐rich spinel (～1 wt% FeO) or fine‐grained intergrowths of these minerals; secondary nepheline and sodalite are very minor. This indicates that AOAs from the reduced CV chondrites are more pristine than those from the oxidized CV chondrites Allende and Mokoia. Although AOAs from the reduced CV chondrites show evidence for high‐temperature nebular annealing (e.g., forsterite grain boundaries form 120° triple junctions) and possibly a minor degree of melting of Al‐diopside‐anorthite materials, none of the AOAs studied appear to have experienced extensive (>50%) melting. We infer that AOAs are aggregates of high‐temperature nebular condensates, which formed in CAI‐forming regions, and that they were absent from chondrule‐forming regions at the time of chondrule formation. The absence of low‐Ca pyroxene and depletion in moderately volatile elements (Mn, Cr, Na, K) suggest that AOAs were either removed from CAI‐forming regions prior to condensation of these elements and low‐Ca pyroxene or gas‐solid condensation of low‐Ca‐pyroxene was kinetically inhibited.     

August 2004

An extension to kinetic theory and hydrodynamic models is proposed that accounts for the existence of multi-particle contacts and leads to a correction of the cooling rate. The other hydrodynamic terms remain unchanged. In the presence of multi-particle contacts a class of different models leads to deviations from the classical inelastic hard sphere (IHS) results. For the homogeneous cooling state (HCS), as examined here, the theoretical results are found to be in perfect agreement with the numerical simulations. We acknowledge partial support from the Deutsche Forschnugsgemeinschaft (DFG) and the Israel Science Foundation, grant no. 53/01.     

Magnetic Reconnection and Turbulent Mixing: From ISM to Clusters of Galaxies

Magnetic reconnection, or the ability of the magnetic field lines that are frozen in plasma to change their topology, is a fundamental problem of magnetohydrodynamics (MHD). Webriefly examine the problem starting with the well-known Sweet-Parker scheme, discuss effectsof tearing modes, anomalous resistivity and the concept of hyperresistivity. We show that the field stochasticity by itself provides a way toenable fast reconnection even if, at the scale of individual turbulent wiggles,the reconnection happens at the slow Sweet-Parker rate. We show that fast reconnectionallows efficient mixing of magnetic field in the direction perpendicular tothe local direction of magnetic field. While the idea of stochastic reconnection still requiresnumerical confirmation,our numerical simulations testify that mixing motions perpendicular to the local magnetic field are upto high degree hydrodynamical. This suggests that the turbulent heattransport should be similar to that in non-magnetized turbulent fluid, namely,should have a diffusion coefficient ～V _L L, whereV _L is the amplitude of the turbulent velocity and L is the scale of the turbulent motions. We present numericalsimulations which support this conclusion. The applicationof this idea to thermal conductivity in clusters of galaxies shows that thismechanism may dominate the diffusion of heat and may be efficient enoughto prevent cooling flow formation.     

Hierarchial galactic dynamo and seed magnetic field problem

A new approach to the galactic seed magnetic field problem is briefly discussed. It is shown that, in early stages of galactic evolution, the hierarchial agglomeration and fragmentation processes can account for the generation of a dynamically important magnetic field. The amplification of this field follows an inverse cascade since a non-zero average value of the field amplified on a smaller scale serves as a seed field on the next (earlier) hierarchial scale. In such a scenario, a problem of how to get things started never occurs as any infinitesimally small battery generated seed field (Lazarian 1992a) can be efficiently amplified passing by through a sufficient number of amplification cascades.     

Alfvén turbulence and the time dependence of non-thermal line broadening in flares

Alfvén wave turbulence is considered as the source of the non-thermal line broadenings observed in soft X-rays in solar flares. The waves are assumed to lose energy to particle acceleration and the temporal development for the case of Fermi acceleration,W(k)k ^–2, is investigated. The decay of the wave energy density is compared to that of the non-thermal velocity for the event of 1980 June 29. The wave energy densities required to explain the degree of non-thermal broadening and its temporal characteristics are consistent with those typically inferred from-ray observations. A relationship between the degree of non-thermal broadening and-ray fluxes is predicted. In general, the larger the-ray flux the shorter the time scales for the decay of the wave energy.