Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results

The chromosphere is a thin layer of the solar atmosphere that bridges the relatively cool photosphere and the intensely heated transition region and corona. Compressible and incompressible waves propagating through the chromosphere can supply significant amounts of energy to the interface region and corona. In recent years an abundance of high-resolution observations from state-of-the-art facilities have provided new and exciting ways of disentangling the characteristics of oscillatory phenomena propagating through the dynamic chromosphere. Coupled with rapid advancements in magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly investigate the role waves play in supplying energy to sustain chromospheric and coronal heating. Here, we review the recent progress made in characterising, categorising and interpreting oscillations manifesting in the solar chromosphere, with an impetus placed on their intrinsic energetics.Comment: 48 pages, 25 figures, accepted into Space Science Review

Optical seeing monitoring at the Oukaïmeden in the Moroccan high atlas mountains: first statistics

In order to complete characterization of the Oukaïmeden site and hoping to prospect other sites in the Moroccan High Atlas, we constructed a seeing monitor. We named the instrument DIMMAR for Differential Image Motion Monitor of Marrakesh. After more than one year of operation, we can conclude that the DIMMAR is quite reliable and that it can be a prototype for other similar low-cost instruments. In this work, the seeing measured at Oukaïmeden site using the DIMMAR on top of a 5 meters high tower is presented. Statistics from fifteen months seeing's are treated (from July 19, 2003 up to September 26, 2004). The median and mean zenith seeing for the entire period of observations are 0.84´´ and 0.92´´, respectively, at 0.5 $\mu\rm m$ (or 0.96´´ and 1.05´´, if corrected for exposure-time bias). The best seeing value measured is 0.32´´.

First characterization of Jbel Aklim in Moroccan Anti-Atlas as a potential site for the E-ELT

Context. In the framework of the European Extremely Large Telescope project (E-ELT), a survey of prospective sites was launched by the European Southern Observatory (ESO) to select a site to host the next generation of optical telescopes of 42 m diameter, i.e., the E-ELT. The Moroccan Anti-Atlas (Jbel Aklim) was selected as one of these sites. Aims. We present an analysis of meteorological parameters and seeing measurements at Aklim, the Moroccan prospective site of the E-ELT project. Methods. We initiated a preliminary campaign to measure the astronomical seeing at Jbel Aklim using a differential image motion monitor (DIMM) instrument. We installed a weather station 2 m above the ground level to measure meteorological parameters such as temperature, relative humidity, pressure, wind speed, and wind direction. Results. We present data obtained by the DIMM monitor during 105 nights. The median and mean values of the seeing for the entire period of observation are 0.72′′ and 0.79′′, respectively, with a standard deviation of 0.31′′. The best value of the seeing obtained during this period is 0.30′′. A seasonal analysis of meteorological parameters are presented. We also used data from the National Center for Environmental Prediction/National Center for Atmospheric Research reanalysis database (NCEP/NCAR) to derive more information about the long-term evolution of atmospheric parameters at Aklim site. Conclusions. Our preliminary results indicate that Aklim has indeed good conditions for conducting astronomical observations and could be a site to host a future astronomical observatory, even of E-ELT dimensions

First statistics of the isopistonic angle for long baseline interferometry

International audienceTo reach a suitable limiting magnitude with a multi-aperture interferometer, we need tocophase the different telescopes using a reference source. The latter should be located in thesame isopistonic domain as the science source. We developed a direct analytical expressionof deducing the isopistonic angle from atmospheric optical parameters as seeing, isoplanaticangle and outer scale. All of these atmospheric turbulence parameters are measured by theGeneralized Seeing Monitor (GSM). The first statistics of the isopistonic angle obtained fromthe GSM data are presented and comparison between the major sites over the world arediscussed (La Silla, Cerro Pachon, Paranal, San Pedro, Mt Palomar, Mauna Kea, La Palma,Ouka ̈ımeden, Maydanak, Dome C). Implications of these isopistonic angle statistics on largeinterferometers cophasing in terms of sky coverage and limiting magnitude are discussed

Paludisme en Guyane : des projets de recherche opérationnelle originaux s'appuyant sur la santé communautaire

International audienceno abstrac

Paludisme en Guyane : des projets de recherche opérationnelle originaux s'appuyant sur la santé communautaire

International audienceno abstrac

Paludisme en Guyane : des projets de recherche opérationnelle originaux s'appuyant sur la santé communautaire

International audienceno abstrac