A transiting planet among 23 new near-threshold candidates from the OGLE survey - OGLE-TR-182

By re-processing the data of the second season of the OGLE survey for planetary transits and adding new mesurements on the same fields gathered in subsequent years with the OGLE telescope, we have identified 23 new transit candidates, recorded as OGLE-TR-178 to OGLE-TR-200. We studied the nature of these objects with the FLAMES/UVES multi-fiber spectrograph on the VLT. One of the candidates, OGLE-TR-182, was confirmed as a transiting gas giant planet on a 4-day orbit. We characterised it with further observations using the FORS1 camera and UVES spectrograph on the VLT. OGLE-TR-182b is a typical ``hot Jupiter'' with an orbital period of 3.98 days, a mass of 1.01 +- 0.15 MJup and a radius of 1.13 (+0.24-0.08) RJup. Confirming this transiting planet required a large investment in telescope time with the best instruments available, and we comment on the difficulty of the confirmation process for transiting planets in the OGLE survey. We delienate the zone were confirmation is difficult or impossible, and discuss the implications for the Corot space mission in its quest for transiting telluric planets.Comment: 7 pages, submitted to Astronomy and Astrophysic

OGLE-TR-211 - a new transiting inflated hot Jupiter from the OGLE survey and ESO LP666 spectroscopic follow-up program

We present results of the photometric campaign for planetary and low-luminosity object transits conducted by the OGLE survey in 2005 season (Campaign #5). About twenty most promising candidates discovered in these data were subsequently verified spectroscopically with the VLT/FLAMES spectrograph. One of the candidates, OGLE-TR-211, reveals clear changes of radial velocity with small amplitude of 82 m/sec, varying in phase with photometric transit ephemeris. Thus, we confirm the planetary nature of the OGLE-TR-211 system. Follow-up precise photometry of OGLE-TR-211 with VLT/FORS together with radial velocity spectroscopy supplemented with high resolution, high S/N VLT/UVES spectra allowed us to derive parameters of the planet and host star. OGLE-TR-211b is a hot Jupiter orbiting a F7-8 spectral type dwarf star with the period of 3.68 days. The mass of the planet is equal to 1.03+/-0.20 M_Jup while its radius 1.36+0.18-0.09 R_Jup. The radius is about 20% larger than the typical radius of hot Jupiters of similar mass. OGLE-TR-211b is, then, another example of inflated hot Jupiters - a small group of seven exoplanets with large radii and unusually small densities - objects being a challenge to the current models of exoplanets.Comment: 6 pages. Submitted to Astronomy and Astrophysic

Analysis of scanner data for crop inventories

There are no author-identified significant results in this report

Cosmology in scalar tensor theory and asymptotically de-Sitter Universe

We have investigated the cosmological scenarios with a four dimensional effective action which is connected with multidimensional, supergravity and string theories. The solution for the scale factor is such that initially universe undergoes a decelerated expansion but in late times it enters into the accelerated expansion phase. Infact, it asymptotically becomes a de-Sitter universe. The dilaton field in our model is a decreasing function of time and it becomes a constant in late time resulting the exit from the scalar tensor theory to the standard Einstein's gravity. Also the dilaton field results the existence of a positive cosmological constant in late times.Comment: 7 pages, Revtex Style, 6 Postscript figure

Entropy, fidelity, and double orthogonality for resonance states in two-electron quantum dots

Resonance states of a two-electron quantum dot are studied using a variational expansion with both real basis-set functions and complex scaling methods. The two-electron entanglement (linear entropy) is calculated as a function of the electron repulsion at both sides of the critical value, where the ground (bound) state becomes a resonance (unbound) state. The linear entropy and fidelity and double orthogonality functions are compared as methods for the determination of the real part of the energy of a resonance. The complex linear entropy of a resonance state is introduced using complex scaling formalism

The Brown-dwarf Atmosphere Monitoring (BAM) Project II: Multi-epoch monitoring of extremely cool brown dwarfs

With the discovery of Y dwarfs by the WISE mission, the population of field brown dwarfs now extends to objects with temperatures comparable to those of Solar System planets. To investigate the atmospheres of these newly identified brown dwarfs, we have conducted a pilot study monitoring an initial sample of three late T-dwarfs (T6.5, T8 and T8.5) and one Y-dwarf (Y0) for infrared photometric variability at multiple epochs. With J-band imaging, each target was observed for a period of 1.0h to 4.5h per epoch, which covers a significant fraction of the expected rotational period. These measurements represent the first photometric monitoring for these targets. For three of the four targets (2M1047, Ross 458C and WISE0458), multi-epoch monitoring was performed, with the time span between epochs ranging from a few hours to ~2 years. During the first epoch, the T8.5 target WISE0458 exhibited variations with a remarkable min-to-max amplitude of 13%, while the second epoch light curve taken ~2 years later did not note any variability to a 3% upper limit. With an effective temperature of ~600 K, WISE0458 is the coldest variable brown dwarf published to-date, and combined with its high and variable amplitude makes it a fascinating target for detailed follow-up. The three remaining targets showed no significant variations, with a photometric precision between 0.8% and 20.0%, depending on the target brightness. Combining the new results with previous multi-epoch observations of brown dwarfs with spectral types of T5 or later, the currently identified variables have locations on the colour-colour diagram better matched by theoretical models incorporating cloud opacities rather than cloud-free atmospheres. This preliminary result requires further study to determine if there is a definitive link between variability among late-T dwarfs and their location on the colour-colour diagram.Comment: 9 pages, 6 figures, 3 tables, accepted for publication in MNRA

Wall effects on granular heap stability

We investigate the effects of lateral walls on the angle of movement and on the angle of repose of a granular pile. Our experimental results for beads immersed in water are similar to previous results obtained in air and to recent numerical simulations. All of these results, showing an increase of pile angles with a decreasing gap width, are explained by a model based on the redirection of stresses through the granular media. Two regimes are observed depending on the bead diameter. For large beads, the range of wall effects corresponds to a constant number of beads whereas it corresponds to a constant characteristic length for small beads as they aggregate via van der Waals forces

Evaluation of the presence of the bap gene in Staphylococcus aureus isolates recovered from human and animals species.

International audienceThe implication of biofilm in chronic bacterial infection in many species has triggered an increasing interest in the characterization of genes involved in biofilm formation. The bap gene is a newly identified gene that encodes the biofilm-associated protein, BAP, which is involved in biofilm formation in Staphylococcus aureus. So far the bap gene has only been found in a small proportion of S. aureus strains from bovine mastitis in Spain. In order to study the presence of the bap gene in S. aureus isolates obtained from other species and various locations, a collection of 262 isolates was tested by PCR, using published primers and dot-blot. The results indicated that none of the isolates carried the bap gene suggesting that the prevalence of this gene among S. aureus isolates should be very low

Interactions zooplancton-poissons dans une retenue oligotrophe de mise en eau récente (Ste-Croix, Provence, France)

Les peuplements zooplanctoniques et piscicoles de la retenue de Sainte-Croix (lac oligotrophe profond) ont été suivis de la mise en eau (1974) à 1986.La phase initiale de colonisation (1974-1975), caractérisée par le calanide Acanthodiaptomus denticornis et la dominance des espèces piscicoles peuplant antérieurement le Verdon lotique (Barbus fluvatilis, Leuciscus cephalus) a été de courte durée. Par la suite, les cladocères sont restés dominants avec cependant de profondes modifications dans la structure du peuplement. En 1977-78, Daphnia longispina était dominante tout au long de l'année (76 %). Plus récemment, cette espèce ne représentait plus que 34 %. des effectifs (1983-84), puis 24 % (1985-1986). La situation actuelle est caractérisée par la présence de Diaphanosoma brachyurum en été et l'abondance des petites formes (bosmines).L'ichtyofaune s'est elle aussi modifiée avec, notamment, une importante population d'ablette (Alburnus cluburnus), exploitant la zone pélagique. Son régime alimentaire est largement zooplanctonophage mais inclut mollusques et insectes lorsqu'elle est capturée en zone littorale.Cette augmentation de la pression de prédation a entraîné un net déplacement du spectre des tailles du zooplancton vers tes classes inférieures à 0,8 mm en 1986 (82 %) alors que les grandes formes ( > à 1 mm) représentaient 60 % des effectifs en 1977-78. Les densités de D. longispina et D. brachyurum décroissent rapidement entre 1983 et 1986.Les conséquences de cette prédation sélective sont discutées (évolution prévisible du système) ainsi que les causes pouvant expliquer l'absence de régulation efficace (densité-dépendance) dans un tel système prédateur-proie.The aim of this study was to identify relationships between changes that occurred, from 1974 to 1986, both in the limnetic zooplankton and the fish communities of the large reservoir of Sainte-Croix (Southern France).This reservoir (figure 1) is characterized by a capacity of 767 hm3 and a long average renewal period (280 days). It was filled up in 1974. Changes in levels can attain 16 m, especially in winter. During summer, the lake is clearly stratified : surface mater temperatures are about 22-250°C whereas waters below the thermocline are cooler ( < 10° C) but well oxygenated (more than 50 % saturation). According to the mean annual total phosphorus (19 mg/m3) and chlorophyll a (ranging from 0.5 to 2 mg/m3), the lake is oligotrophic.The zooplankton was collected with a Clarke-Bumpus devise sampler (125 µm mesh-size) during both the 1974-1978 and the 1983-1984 periods. More recently (1985-1986), vertical hauls of zooplankton were made with a 50 µm mesh-size aperture net. Only relative abundance of large species (excluding small rotifers) have been taken into account for comparisons between different periods (figure 2). For the last four years (1983-1986), a set of data on filtration efficiency and comparison between sampling methods provides information concerning the evolution of annual mean densities of zooplankton species (figure 3).Successive inventories of the fish species were made in 1976, 1977, 1984 and 1987 at the same location with 15 mm, 27 mm and 50 mm mesh-size nets respectively. Figure 1 shows that abundant autochtonous species (Chondrostoma chondrostoma, Barbus fluviatilis) during the first period (1976-1977) are now relatively scarce, whereas the roach (Rutilus rutilus), an introduced species, is now largely dominant. Likewise, the relative abundance of the bleak, Alburnus alburnus, also increased, especially during the last period (1984-1987). Only this last species was caught by fine mesh-size nets in the pelagic epilimnion. Adults fed mostly on zooplankton but also took more molluscs in the littoral area (stomach analysis).In 1974, one year after an overflow, the calanoid Acanthodiaptomus denticornis represented the majority of zooplankton collected but it disappeared quickly. Since 1976, cladocerans are largely dominant. General evolutive trends show a decrease in relative abundance of Daphnia longispina from 1978 to 1986 whereas Diaphanosoma brachyurum have been recorded since 1983. Quantitative data (figure 3), available for the fast 4 years (1983-1986) show that the population densities of both these two large cladoceran and cyclopoïd species (mainly Macrocyclops albius) declined radically. On the other hand, small species such as Bosmina longirostris, Bosmina coregoni and Asplancha priodonta exhibited the same population densities throughout the fast period. Comparisons of phytoplankton community structure from 1982 to 1986 do not show signicative trends. Thus, variations in resource abundance cannot explain the long-term evolution of zooplankton communities.By comparing the mean annual length frequency distributions of zooplankton in 1977-78 and 1986 (figure 4), a marked decline of large bodied forms is seen. The individuals larger than 1.0 mm represented 60 % of total organisms in 1977-73 against 14.5 % in 1986. Mean annual lenghts were 0.8 mm in 1977-78 and 0.3 mm in 1986. These results are in good agreement with BROOKS and DODSON hypothesis that planktivorous fish can have a profound effect on zooplankton community taxonomics and size structure. They show that the control of structure and abundance of zooplankton by fish predation in new man-made lakes is a reality.Most fish are general predators. As demonstrated by MURDOCH and BENCE (1987), this can explain the instability of the coupled predator-prey system in the pelagic portion of Sainte-Croix reservoir because of : i) the capacity of the bleak to use fat reserves and to change its diet when large zooplankton prey density is too low, ii) the generation time of the predator is much longer than that of planktonic preys. Thus, the classical density-dependence mechanisms do not stabilize the predator-prey system and the main planktonic prey tend to disappear (D. longispina, in our case).Nevertheless, some potentially stabilizing mechanisms could interfere in the system before the local extinction of the prey : compensatory responses by the prey and significant changes in the fish community. There is reason to consider :1) The existence of refuges in space. Vertical size distribution of D. longispina (unpublished data) show that there is a strong vertical size gradient during daylight hours. Larger-bodied reproductive forms (longer than 1 mm) are only present in the deeper layers (20-30 m) whereas, during the night all the organises migrate to the superficial layer.2) The existence of refuge in time. In the past (1976-1978), D. longispina was dominant all year around. More recently (1983-1986), population densities were high only in spring (figure 5). From April to June, bleaks tend to assemble in the littoral zone for reproduction.3) An increase in the bleak mortality rate due to a recent development of large predator populations, such as Esox esox, could permit a reduction or, at least, a stabilization of the bleak population growth rate

An ingress and a complete transit of HD 80606 b

We have used four telescopes at different longitudes to obtain near-continuous lightcurve coverage of the star HD 80606 as it was transited by its \sim 4-MJup planet. The observations were performed during the predicted transit windows around the 25th of October 2008 and the 14th of February 2009. Our data set is unique in that it simultaneously constrains the duration of the transit and the planet's period. Our Markov-Chain Monte Carlo analysis of the light curves, combined with constraints from radial-velocity data, yields system parameters consistent with previously reported values. We find a planet-to-star radius ratio marginally smaller than previously reported, corresponding to a planet radius of Rp = 0.921 \pm 0.036RJup .Comment: 6 pages, 2 figures, MNRAS accepte