Object DUO 2: A New Binary Lens Candidate

We present the light curve of an unusual variable object, DUO 2, detected during the search for microlensing events by the DUO project. The star remained stable for more than 150 days before it brightened by more than two magnitudes in 6 days in the B and R bands. The light curves are achromatic during the variability. We consider possible explanations of the photometric behavior, with particular emphasis on the binary lens interpretation of the event. The masses of the lenses are quite small, with the companion possibly in the range of a brown dwarf or even a few times of Jupiter. We report evidence of blending of the source by a companion through the first detection of shift in the light centroid among all the microlensing experiments. This shift sets a lower limit of $0.3^{\prime\prime}$ on the separation between the stars. The best lens model obtained requires moderate blending, which was what motivated us to check the centroid shift that was subsequently found. The best lens model predicts a separation of $1^{\prime\prime}$ between the two blended stars. This prediction was recently tested using two CCD images taken under good seeing conditions. Both images show two components. Their separation and position angle are in good agreement with our model.Comment: uuencoded, compressed PostScript, 4 pages, 4 figures (in text). Accepted for publication in Astronomy and Astrophysics Letter

AGAPEROS: Searching for variable stars in the LMC Bar with the Pixel Method. I. Detection, astrometry and cross-identification

We extend the work developed in previous papers on microlensing with a selection of variable stars. We use the Pixel Method to select variable stars on a set of 2.5 x 10**6 pixel light curves in the LMC Bar presented elsewhere. The previous treatment was done in order to optimise the detection of long timescale variations (larger than a few days) and we further optimise our analysis for the selection of Long Timescale and Long Period Variables (LT&LPV). We choose to perform a selection of variable objects as comprehensive as possible, independent of periodicity and of their position on the colour magnitude diagram. We detail the different thresholds successively applied to the light curves, which allow to produce a catalogue of 632 variable objects. We present a table with the coordinate of each variable, its EROS magnitudes at one epoch and an indicator of blending in both colours, together with a finding chart. A cross-correlation with various catalogues shows that 90% of those variable objects were undetected before, thus enlarging the sample of LT&LPV previously known in this area by a factor of 10. Due to the limitations of both the Pixel Method and the data set, additional data -- namely a longer baseline and near infrared photometry -- are required to further characterise these variable stars, as will be addressed in subsequent papers.Comment: 11 pages with 10 figure

L’entreprise sociale – SCIC entre intégration et tensions : le cas du secteur culturel

International audienc

L’importance des modes de régulations dans l’inscription des activités sportives dans le ‘’développement durable’’. Les cas du cyclotourisme et du tourisme équestre en Pays de la Loire et du surf en Aquitaine

International audienc

The effect of EGR on HCCI combustion – impact of diluting, thermal and chemical aspects: experimental and numerical approaches

peer reviewe

Complexité et auto-organisation en entrepreneuriat collectif : analyse d’une scène musicale locale

The purpose of this paper is to propose a different way of understanding the entrepreneurial process than its conception as an individualist phenomenon. It describes a kind of collective entrepreneurship that aims at building a context for entrepreneurial processes (and not a venture creation or an innovative activity). It analyzes the emergence of a local music scene essentially based on amateur volunteer activities. Drawing on the perspective of entrepreneuring (Steyaert, 2007) and the territorial approach in entrepreneurship (Julien, 2005), it investigates interactions between actors and phenomena of embeddedness to answer the following questions: how is such a context formed? What does it create? What is its organizational process? The results refutes a causal and linear vision of the entrepreneurial process, an approach which does not allow us to understand the specific phenomena studied in this case. Our study reveals a collective action that is both self-organized and emergent. The interest of the results is thus in looking for a better understanding of the complexity and creativity inherent in entrepreneurship

Circulating microparticles from pulmonary hypertensive rats are vectors of oxidative stress

Date du colloque : 04/2010National audienc