ISO observations of the planetary nebula Lindsay 305 in the Small Magellanic Cloud

We present ISO (Infrared Space Observatory) observations of the planetary nebula Lindsay 305 (L 305) in the Small Magellanic Cloud. L 305 is very prominent in the ISOCAM frames at 6.75 and 11.5 $\mu$m, although it is under the detection limit at 4.5 $\mu$m. The obtained spectral energy distribution shows a strong mid-IR excess, which, depending on the amount of energy radiated at wavelengths longer than 11.5 $\mu$m, may be as large as $\sim 1500 L_{\odot}$. However, since an accurate estimate of the total nebular luminosity is not available up to date, the evolutionary status of L 305 can not yet be constrained precisely.Comment: 4 pages, 2 figures, to appear in the Publications of the Astronomical Society of Japa

Variation around a Pyramid theme: optical recombination and optimal use of photons

We propose a new type of Wave Front Sensor (WFS) derived from the Pyramid WFS (PWFS). This new WFS, called the Flattened Pyramid-WFS (FPWFS), has a reduced Pyramid angle in order to optically overlap the four pupil images into an unique intensity. This map is then used to derive the phase information. In this letter this new WFS is compared to three existing WFSs, namely the PWFS, the Modulated PWFS (MPWFS) and the Zernike WFS (ZWFS) following tests about sensitivity, linearity range and low photon flux behavior. The FPWFS turns out to be more linear than a modulated pyramid for the high-spatial order aberrations but it provides an improved sensitivity compared to the non-modulated pyramid. The noise propagation may even be as low as the ZWFS for some given radial orders. Furthermore, the pixel arrangement being more efficient than for the PWFS, the FPWFS seems particularly well suited for high-contrast applications.Comment: 4 pages, 4 figures, accepted for publication in Optics Letters - Version corrected for affiliation

Post processing of differential images for direct extrasolar planet detection from the ground

The direct imaging from the ground of extrasolar planets has become today a major astronomical and biological focus. This kind of imaging requires simultaneously the use of a dedicated high performance Adaptive Optics [AO] system and a differential imaging camera in order to cancel out the flux coming from the star. In addition, the use of sophisticated post-processing techniques is mandatory to achieve the ultimate detection performance required. In the framework of the SPHERE project, we present here the development of a new technique, based on Maximum A Posteriori [MAP] approach, able to estimate parameters of a faint companion in the vicinity of a bright star, using the multi-wavelength images, the AO closed-loop data as well as some knowledge on non-common path and differential aberrations. Simulation results show a 10^-5 detectivity at 5sigma for angular separation around 15lambda/D with only two images.Comment: 12 pages, 6 figures, This paper will be published in the proceedings of the conference Advances in Adaptive Optics (SPIE 6272), part of SPIE's Astronomical Telescopes & Instrumentation, 24-31 May 2006, Orlando, F

Study of pollution in the El Jadida-Safi Atlantic coastal zone (Morocco) by using PIXE and SSNTD methods

In this work PIXE experiments were performed for measuring heavy and light elements (ranging from aluminium to lead) concentrations inside various polluted and unpolluted soils as well as liquid samples collected from different phosphate factory sewers in the El Jadida-Safi Atlantic coastal region (Morocco). In addition, uranium (238U) and thorium (232Th) contents were evaluated in the same samples studied by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). The influence of the phosphate industry wastes on the concentrations of both radioactive and non-radioactive elements of the samples studied was investigated

Nitrogen dynamics in the shallow groundwater of a riparian wetland zone of the Garonne, SW France: nitrate inputs, bacterial densities, organic matter supply and denitrification measurements

This study highlights the role of interactions between surface and sub-surface water of the riparian zone of a large river (the Garonne, SW France). Information is given about the role of surface water in supplying Dissolved Organic Carbon (DOC ) to the riparian zone for nitrate removal processes. The densities of bacteria (up to 3.3106 cell m L-1) in groundwater are strongly conditioned by the water moving during flood events. Total bacterial densities in groundwater were related to surface water bacterial densities. In sediment, total bacteria are attached mainly to fine particles (90 % in the fraction < 1 mm). Spatial variations in organic carbon and nitrate content in groundwater at the site studied are correlated with exchanges between the groundwater and the river, from the upstream to the downstream part of the meander. Total bacterial densities, nitrate and decressing organic carbon concentrations follow the same pattern. These results suggest that, in this kind of riparian wetland, nitrate from alluvial groundwater influenced by agricultural practices may be denitrified by bacteria in the presence of organic carbon from river surface water

Advances in multi-elementary analysis of fluid or solid micro-crystalline inclusions (12

International audienceX-Ray-based analytical methods can be applied in an absolute fashion, provided that matrix effects are calculated and that parameters related to instrumental factors are controlled (Newbury, 1986). When EPMA (Electron Probe Micro Analysis) was conceived at the end of the 60's, this potentiality was abandoned, as the instrument works in a relative fashion, by comparison with standards. At the end of the 70's and in the 80's, PIXE (Proton Induced X-Ray Emission) by contrast was applied in a way that preserved the possibility of an absolute application: the computer programs developed to interpret PIXE spectra calculate matrix effects and also integrate instrumental factors (e.g., Maxwell et al., 1989). In spite of this advantage, and also despite the fact that PIXE application extends to trace element analysis, the development of PIXE in the scientific community was sluggish, in deep contrast with the widespread applications of EPMA. In the field of Earth Sciences particularly, EPMA was recognized by the Mineralogical Society of America to have had 'a revolutionary, profound impact on mineralogy and petrology'. In the same time, PIXE applications remained mainly restricted to trace element analysis, and the potential accuracy of the method was never clearly realized. A first aim of this presentation is to show that, using a simple standardization procedure, the multi-elementary absolute capability of PIXE can be revealed. This in turn changes PIXE into a tool of quantitative mineralogy and trace element geochemistry. We then show that, by coupling PIXE to PIGE (Proton Induced Gamma Ray Emission) and RBS (Rutherford Back Scattering) spectrometries, the Nuclear Microprobe becomes a tool for quantitative mineralogy s.l. and geochemistry, i.e., an instrument to analyze all major to trace elements from Li to U in minerals and their inclusions. In the second part of the presentation, we illustrate the capability of µ-PIXE to analyze in situ individual fluid inclusions that have been carefully localized in space and time. The Hercynian French Massif Central and its sedimentary eastern margin are part of a large European Carbonic Province, which hosts numerous deep CO2 reservoirs and carbonic springs (Blavoux, Dazy, 1990). Carbonic fluids are present at all stages of the long-lived evolution of this crustal segment, from deep metamorphic fluids involved in a thrusting event at 340 M.a to mantle-derived volcanic CO2 related to Neogene volcanism. In order to characterize the main aquo-carbonic fluid reservoirs through time in this crustal segment, we present preliminary data on the trace element content of aquo-carbonic inclusions trapped in the schists at peak and retrograde metamorphic conditions, and compare them to contemporaneous granite-related fluid inclusion