ARTEMiS (Automated Robotic Terrestrial Exoplanet Microlensing Search): A possible expert‐system based cooperative effort to hunt for planets of Earth mass and below

The technique of gravitational microlensing is currently unique in its ability to provide a sample of terrestrial exoplanets around both Galactic disk and bulge stars, allowing to measure their abundance and determine their distribution with respect to mass and orbital separation. Thus, valuable information for testing models of planet formation and orbital migration is gathered, constituting an important piece in the puzzle for the existence of life forms throughout the Universe. In order to achieve these goals in reasonable time, a well‐coordinated effort involving a network of either 2m or 4×1m telescopes at each site is required. It could lead to the first detection of an Earth‐mass planet outside the Solar system, and even planets less massive than Earth could be discovered. From April 2008, ARTEMiS (Automated Robotic Terrestrial Exoplanet Microlensing Search) is planned to provide a platform for a three‐step strategy of survey, follow‐up, and anomaly monitoring. As an expert system embedded in eSTAR (e‐Science Telescopes for Astronomical Research), ARTEMiS will give advice for follow‐up based on a priority algorithm that selects targets to be observed in order to maximize the expected number of planet detections, and will also alert on deviations from ordinary microlensing light curves by means of the SIGNALMEN anomaly detector. While the use of the VOEvent (Virtual Observatory Event) protocol allows a direct interaction with the telescopes that are part of the HTN (Heterogeneous Telescope Networks) consortium, additional interfaces provide means of communication with all existing microlensing campaigns that rely on human observers. The success of discovering a planet by microlensing critically depends on the availability of a telescope in a suitable location at the right time, which can mean within 10 min. To encourage follow‐up observations, microlensing campaigns are therefore releasing photometric data in real time. On ongoing planetary anomalies, world‐wide efforts are being undertaken to make sure that sufficient data are obtained, since there is no second chance. Real‐time modelling offers the opportunity of live discovery of extra‐solar planets, thereby providing “Science live to your home”. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Modal abundances of CAIs: Implications for bulk chondrite element abundances and fractionations

Abstract— Modal abundances of Ca,Al‐rich inclusions (CAIs) are poorly known and reported data scatter across large ranges. CAIs are Poisson distributed, and if only small areas (<1000 mm²) are studied, the data are probably not representative of the true CAI modal abundances, explaining their reported large scatter in a single chondrite group. We combine reported CAI modal abundances and our own set, and present a complete list of CAI modal abundances in carbonaceous chondrites. This includes (in area%): CV: 2.98, CM: 1.21, Acfer 094: 1.12, CO: 0.99, CK/CV (Ningqiang and Dar al Gani [DaG] 055): 0.77, CK: 0.2, CR: 0.12 and CB: 0.1. CAIs are Poisson distributed and if only small areas are studied, the data are probably not representative of the true CAI modal abundances, Carbonaceous chondrites have excess bulk Al concentrations when compared to the CI‐chondritic value. We find a correlation between this excess and CAI modal abundances and conclude that the excess Al was delivered by CAIs. The excess Al is only a minor fraction (usually ?10 rel%, but 25 rel% in case of CVs) of the bulk chondrite Al and cannot have contributed much ²⁶Al to heat the chondrite parent body. Ordinary, enstatite, R and K chondrites have an Al deficit relative to CI chondrites and only very low CAI modal abundances, if any are present at all. Carbonaceous chondrites also had an initial Al deficit if the contribution of Al delivered by CAIs is subtracted. Therefore all chondrites probably lost a refractory rich high‐T component. Only minor amounts of CAIs are present in the matrix or have been present in the chondrule precursor aggregates. Most CAI size distributions contain more than one size population, indicating that CAIs from within a single meteorite group had different origins.     

In situ micro‐Raman and X‐ray diffraction study of diamonds and petrology of the new ureilite UAE 001 from the United Arab Emirates

Abstract— A new olivine‐pigeonite ureilite containing abundant diamonds and graphite was found in the United Arab Emirates. This is the first report of a meteorite in this country. The sample is heavily altered, of medium shock level, and has a total weight of 155 g. Bulk rock, olivine (Fo_79.8–81.8) and pyroxene (En_73.9–75.2, Fs_15.5–16.9, Wo_8.8–9.5) compositions are typical of ureilites. Olivine rims are reduced with Fo increasing up to Fo_96.1–96.8. Metal in these rims is completely altered to Fehydroxide during terrestrial weathering. We studied diamond and graphite using micro‐Raman and in situ synchrotron X‐ray diffraction. The main diamond Raman band (LO = TO mode at ?1332 cm^?1) is broadened when compared to well‐ordered diamond single crystals. Full widths at half maximum (FWHM) values scatter around 7 cm^?1. These values resemble FWHM values obtained from chemical vapor deposition (CVD) diamond. In situ XRD measurements show that diamonds have large grain sizes, up to >5 μm. Some of the graphite measured is compressed graphite. We explore the possibilities of CVD versus impact shock origin of diamonds and conclude that a shock origin is much more plausible. The broadening of the Raman bands might be explained by prolonged shock pressure resulting in a transitional Raman signal between experimentally shock‐produced and natural diamonds.     

A marine pebbly mudstone from the Swiss Alps: palaeotectonic implications and some consequences for the interpretation of Precambrian diamictites

Pebbly mudstones are a conspicuous element of sedimentary sequences deposited in different tectonic settings and sedimentary environments. Whereas for many diamictites a glacial origin seems plausible, the problem to distinguish glacial from non-glacial diamictites is often difficult for Precambrian examples where palaeoclimatic constraints are generally lacking. This article documents an Eocene pebbly mudstone of the Southhelvetic nappes of eastern Central Switzerland (Blockmergel) for which a glacial origin can be firmly rejected and which may thus serve as an example for non-glacial marine diamictites and their sedimentary and palaeotectonic environment. The Blockmergel are interpreted as the product of gravitational deposition of single blocks across steep palaeo-slopes (subaqueous rockfall) into a basin otherwise dominated by suspension settling sedimentation. The Blockmergel occur within the basal part of the early fill of the North Alpine Foreland Basin, which constitutes a deepening upward sequence above basal shallow marine limestones. The Blockmergel demonstrate substantial Middle to Late Eocene sub-aerial erosion and fluvial transport (producing the rounded pebbles) and local extensional fault movements in the proximal part of the incipient North Alpine Foreland Basin. They are capped sharply by forced-regressive shoreface sandstones and the whole sequence thus demonstrates locally very shallow to subaerial conditions within an otherwise rather deep hemipelagic marine basin. This, and the extensional fault movements, are linked to a long-standing feature of Helvetic palaeogeography—the Southhelvetic swell zone. That this swell still operated during the Priabonian i.e. shortly before finally being overthrust by the orogenic wedge of the evolving Alpine orogen is a new element in Alpine palaeotectonics and seems to highlight the importance of the reactivation of inherited palaeotectonic faults. Finally, the example of the Blockmergel is suggested as a useful analogue to help distinguishing glacial-sourced from slope-derived diamictites in the Neoproterozoic sedimentary record and may thus help resolving the “diamictite dichotomy”.     

Probabilistic Marcinkiewicz–Zygmund Inequalities on the Rotation Group

Approximation problems on the rotation group SO(3) naturally arise in various fields, like crystallography, chemistry, and biology. For example, in crystallographic texture analysis one is confronted with the problem of evaluating so-called orientation density functions (ODFs). In many situations one only has a finite number of measurements at scattered sampling nodes. In order to reconstruct ODFs over all rotations, so-called Marcinkiewicz–Zygmund inequalities on the rotation group are an important tool. These inequalities provide norm equivalences between polynomials on SO(3) and their sample values. Recently shown equivalences depend on a density parameter of the sampling set and the proven inequalities hold true for polynomials on SO(3) whose degree does not exceed an upper bound which is determined by this density parameter. In this paper, we show that we can enlarge this upper bound for the polynomial degree significantly if we are satisfied by such norm equivalences that hold with a given probability only. Moreover, we show that there are fixed sampling sets for which we get probabilistic Marcinkiewicz–Zygmund inequalities that hold for polynomials on SO(3) of all degrees.     

Denman 002: A new CV3 chondrite from South Australia

Abstract— Denman 002 is a new Australian carbonaceous chondrite. A single stone of 30 g was recovered in 1991 May near Fisher Station on the Trans Australian Railway, Nullarbor Plain, South Australia (30°36′S, 130°04′E). Texture, mineral and chemical composition indicate that it is a CV3 chondrite of oxidised subgroup with several similarities to Allende. It is composed of sharply defined chondrules, Ca-Al rich inclusions up to 3.5 mm across, olivine aggregates and fine-grained, nearly opaque matrix (40 vol%). Silicates are compositionally highly heterogeneous (olivine Fa: 0.2–45.6 mol%, PMD: 109.7). Denman 002 shows shock effects of stage SI and weathering of category A.     

Radioisotopic evidence of perturbations of recent sedimentary record in lakes: a word of caution for climate studies

The rate of climatic change estimated from the gradient of signals recorded in lake sediments may be erroneous if post-depositional perturbations are overlooked. A smear out of a pulse signal, over a variable thickness of core section, due to physical or biological mixing, is a well known phenomena. Much less attention is paid to a possible overestimation of the rate of change when a part of record is missing due to an erosion event. In this paper we show a few examples of recent lake sediment perturbations and the resulting distortions in the time scale, as documented by short-lived radionuclides.Contribution to Clima Locarno — Past and Present Climate Dynamics; Conference September 1990, Swiss Academy of Sciences — National Climate Program     

Seasonal delivery of the particulate forms of phosphorus to Lake Geneva from the upper Rhone river

Large volume water samples were taken at Porte du Scex and Bouveret at the mouth of the Upper Rhone River as it enters Lake Geneva. Samples were taken every two weeks during 1982 up until August 1983. Water samples were analyzed for total phosphorus (TP), and soluble reactive phosphorus (SRP) and were centrifuged in the field using a continuous flow centrifuge to recover the suspended solids following sieving at 63 µm. The < 63 µm solids were analyzed for total particulate phosphorus (TPP), organic phosphorus (OP), apatite phosphorus (AP) and non apatite inorganic phosphorus (NAIP). The > 63 µm were similarly analyzed and the weight of total solids in both size fractions recorded. Results were compared throughout the period of record to the hydrograph situated at Porte de Scex. The annual cycle of the Rhone can be divided into a low turbidity, low flow winter period (SED 1) and high flow, high turbidity summer season designated (SED 2). Turbidity is well related to discharge. The > 63 µm sediment is mobilized at 200 m³ s^–1 and thereafter increases in concert with, though at a faster rate than, the < 63 µm fraction. The coarse fraction contains significant quantities of phosphorus and in 1982 accounted for 26% of the TPP loading. OP and NAIP are higher in SED 1 than in SED 2 though AP remains constant throughout the year. OP is believed to be driven primarily from point sources whereas NAIP, in addition to point sources, has secondary sources in spring and summer due to sheet erosion from the agricultural soils of the valley. Loadings of phosphorus were calculated by four methods which showed internal consistency though they were higher than previous estimates. Bioavailable phosphorus (BAP) was estimated to account for some 20% of the total phosphorus loading of some 1500 tonnes; BAP is here taken to be the sum of SRP and NAIP and is that portion of the phosphorus load believed to be available to generate phytoplankton growth.     

Texture and sedimentation rates in Lake Geneva

Thirty two cores were collected from Lake Geneva sediments along one longitudinal and eight transverse profiles. Rates of sedimentation determined by¹³⁷Cs vary from 0.01 to 1.86 g cm⁻² y⁻¹. The average deposition rates in coastal and slope areas amounts to 0.37 g cm⁻² y⁻¹ in the Upper Lake (Grand Lac) and 0.12 g cm⁻² y⁻¹ in the Lower Lake (Petit Lac). In the deep basins, average rates of 0.13 and 0.05 g cm⁻² y⁻¹ were found for the Grand Lac and Petit Lac, respectively. The estimated mass of sediment deposited yearly outside of the principal deltas and turbidity current depositional areas is about 1.0 million tons (about 13% of the estimated total river load). One turbidite is clearly identified in the deepest, central lake area. There is little variation of surface sediment texture (mean grain size about 8–9μm) with the exception of delta areas. Since the beginning of the twentieth century, both carbonate and organic matter have increased as a result of lake eutrophication.