Relative astrometric and photometric measurements of visual binaries made with the Nice 76-cm refractor in 2008

8 pages dans la version publiée sans les tables 55 pages dans la version avec les tables complètesInternational audienceWe present relative astrometric and photometric measurements of visual binaries made in 2008, with the 76-cm refractor of Côte d'Azur Observatory. Our observing list contains orbital couples as well as binaries whose motion is still uncertain. Three different techniques were used for obtaining measurements: Lucky imaging, speckle interferometry and the Direct Vector Autocorrelation method. We obtained 2420 new measurements of the relative position of 2225 objects, with angular separations in the range 0.07 arcsec-11.5 arcsec, and an average accuracy of 0.02 arcsec. The mean error on the position angles is 0.6 deg. We managed to observe faint systems (m_V ≈ 12) with large magnitude difference (up to Δ m_V ≈ 5). We have thus been able to measure many systems containing red dwarf stars that had been poorly monitored since their discovery. We also measured the difference of magnitude of the two components of 376 objects with an estimated error of 0.1 mag. Finally, we provide a list of 33 newly discovered components of multiple or binary systems, which is a significant complement to our GII catalog. } %% end abstrac

PISCO2: the new speckle camera of the Nice 76-cm refractor

We present the new speckle camera PISCO2 made in 2010-2012, for the 76-cm refractor of C\^ote d'Azur Observatory. It is a focal instrument dedicated to the observation of visual binary stars using high angular resolution speckle interferometry techniques to partly overcome the degradation caused by the atmospheric turbulence. Fitted with an EMCCD detector, PISCO2 allows the acquisition of short exposure images that are processed in real time by our specially designed software. Two Risley prisms are used for correcting the atmospheric dispersion. All optical settings are remotely controlled. We have already been able to observe faint, close binary stars with angular separations as small as 0".16, and visual magnitudes of about 16. We also have measured some particularly difficult systems with a magnitude difference between the two components of about 4 magnitudes. This level of performance is very promising for the detection and study of large sets of yet unknown (or partly measured) binaries with close separation and/or large magnitude difference.Comment: 13 pages, 12 figure

Manejo sitio-específico de la tierra para mejorarla eficiencia de uso de recursos y el nivel de los servicios ecosistémicos

La “intensificación ecológica” tiene por objetivo igualar o aumentarlos niveles de rendimiento y reducir al mínimo los impactos negativos sobre el medio ambiente, y consecuentemente sobre la productividad agrícola, a través de la integración de la gestión de los servicios ecosistémicos suministrados por la biodiversidad de los sistemas de producción. Sin embargo, no se han desarrollado aún recomendaciones acerca de cómo poner en práctica este planteo novedoso para producir más alimento sin perjudicar los recursos naturales. El presente proyecto tiene por objeto desarrollar recomendaciones para el uso y manejo de suelos que permitan incrementar la productividad en sitios de alta calidad y reducir la presión productiva en sitios menos resilientes, de acuerdo a las premisas de la intensificación ecológica. El área de estudio comprende la región semiárida central, dónde se relevarán y mapearán las características de las unidades suelo-paisaje con un enfoque sobre las limitaciones productivas que presenten, para conformar un mapa de áreas agro-ecológicamente homogéneas (sitios agroecológicos). Además se desarrollarán ensayos en campos de productores para evaluar rotaciones de cultivo, cultivos de cobertura y efecto de la fertilización entre otras prácticas de manejo que representen sistemas más eficientes para la utilización de los recursos en el marco de la intensificación ecológica. Se monitoreará la calidad de los servicios ecosistémicos utilizando indicadores de calidad física, química y biológica de los suelos. Los resultados esperados incluyen mapas de unidades suelo-paisaje, la evaluación cuantitativa de los servicios ecosistémicos, la productividad de los sitios agro-ecológicos y recomendaciones de manejo y uso de suelos en las diferentes áreas agro-ecológicas. El objetivo general del presente proyecto consiste en desarrollar y aplicar criterios teóricamente fundamentados y científicamente comprobados para delimitar zonas de manejo homogéneas con el fin de mejorar la eficiencia de uso de los recursos y lograr la intensificación ecológica con alto nivel de los servicios ecosistémicos. El manejo sitio-especifico cobra especial interés en regiones donde la calidad de las tierras es altamente variable en escalas espaciales a nivel de potrero, y en las cuales las condiciones agro-ecológicas imponen diferentes grados de limitación para la producción de los cultivos. Es por este motivo que el manejo sitio-especifico resultará en mayores beneficios, tanto económicos como ambientales, en regiones marginales tales como la región semiárida central. Esta región se caracteriza por presentar limitaciones en cuanto a la disponibilidad de agua para los cultivos y por grandes diferencias en la capacidad de retención de agua de los suelos. Estos factores se conjugan para determinar el potencial productivo de las tierras que resulta ser muy heterogéneo en el paisaje y a nivel de potrero. El manejo uniforme de cultivos no solo produce disparidad de rendimientos y disminución de la rentabilidad de los cultivos, sino también, desencadena procesos de degradación de los suelos sometidos a usos y manejos no adecuados. El impacto del presente proyecto es que el manejo sitio-especifico optimizará la eficiencia de uso del agua y la productividad de los cultivos, y por ende, también incrementará la rentabilidad de las empresas agropecuarias y ayudará a la prevención de la desertificación en la región semiárida central. La presente propuesta está orientada hacia la integración de los conocimientos y capacidades existentes en la institución, lo cual redundará en una visión más holística del agro-ecosistema y de su manejo. La integración de productores y empresas en el desarrollo del proyecto a través de una gestión participativa de la investigación mejorará las capacidades de transferencia y extensión de la Facultad, colocándola como referente en este tema novedoso y de poco desarrollo en el país. Por otra parte, este proyecto también creará las bases teóricas y las experiencias locales para el desarrollo de una carrera de Especialización en Manejo Sitio-Especifico en la Facultad de Agronomía de la UNLPam. El proyecto aborda una problemática que no ha sido resuelta todavía en el ámbito nacional e internacional. El conocimiento generado a partir de este proyecto contribuirá a consolidar los conceptos de los factores que determinan la interacción entre condiciones ambientales y respuesta de cultivos al manejo sitio-específico en términos productivos y económicos. Se espera que a partir de los resultados alcanzados se podrán desarrollar sistemas de soporte de decisión y el software adecuado para las sembradoras y la maquinaria de aplicaciones de fertilizantes y agroquímicos de dosis variables, que hasta la fecha se calibran sobre la base de información aleatoria (mapas de rendimiento) o provistos por empresas comerciales sin base científica. Por otra parte, el desarrollo de variables indicadoras para la cuantificación de los servicios ecosistémicos es crucial para proveer herramientas objetivas y científicamente comprobadas para las decisiones de políticas ambientales

The Biology and Economics of Coral Growth

To protect natural coral reefs, it is of utmost importance to understand how the growth of the main reef-building organisms—the zooxanthellate scleractinian corals—is controlled. Understanding coral growth is also relevant for coral aquaculture, which is a rapidly developing business. This review paper provides a comprehensive overview of factors that can influence the growth of zooxanthellate scleractinian corals, with particular emphasis on interactions between these factors. Furthermore, the kinetic principles underlying coral growth are discussed. The reviewed information is put into an economic perspective by making an estimation of the costs of coral aquaculture

Measurements of visual binaries with EMCCD cameras and the Nice 76-cm refractor in 2009-2010

International audienceWe present relative astrometric and photometric measurements of visual binaries made in 2009-2010, with the 76-cm refractor of Côte d’Azur Observatory and a pair ofsensitive EMCCD ANDOR cameras. Ourobserving list consists of optical pairs and binaries whoseorbital motion is still uncertain. Three differenttechniques were used for obtaining measurements: Lucky Imaging, Speckle Interferometry and the Direct Vector Autocorrelation method. From the 2050 observationsof double stars that we performed, we obtained1652 new measurements of the relative position of 1792 objects, with angular separations in the range 0′′.1— 14′′.1. The average accuracy is estimated at 0′′.02 for the angular separations and 0◦.6 for the positionangles. We managed to observe faint systems (mV≈12) with large magnitude difference (up to ∆mV≈5).We have thus been able to measure many systems containing reddwarf stars that had been poorly monitoredsince their discovery. We also measured the difference of magnitude of the two components of 1143 objectswith an estimated error of 0.2 mag

Measurements of visual binaries with EMCCD cameras and the Nice 76-cm refractor in 2009-2010

International audienceWe present relative astrometric and photometric measurements of visual binaries made in 2009-2010 with the 76-cm refractor of Côte d'Azur Observatory and a pair of sensitive EMCCD ANDOR cameras. Our observing list includes optical pairs and binaries whose orbital motion is still uncertain. Three different techniques were used for obtaining measurements: Lucky Imaging, Speckle Interferometry, and the Direct Vector Autocorrelation method. From our 2,050 observations of double stars, we obtained 1,652 new measurements of the relative position of 1,792 objects, with angular separations in the range 0".1-14".1. The average accuracy is estimated at 0".02 for the angular separations and 0°.6 for the position angles. We managed to observe faint systems (mV ≈ 12) with a large magnitude difference (up to ΔmV ≈ 5). We have thus been able to measure many systems containing red dwarf stars that had been poorly monitored since their discovery. We also measured the difference of magnitude of the two components of 1,143 objects with an estimated error of 0.2 mag

Measurements of visual binaries with PISCO2 at the Nice 76-cm refractor in 2013-2014

International audienceWe present relative astrometric and photometric measurements of visual double stars made in 2013-2014, with PISCO2 installed at the 76-cm refractor of Côte d’Azur Observatory in Nice (France). Our observing list contains orbital couples as well as double stars whose motion is still uncertain. Three different techniques were used for obtaining measurements: Lucky Imaging, Speckle Interferometry and the Direct Vector Autocorrelation method. From our observations of 4864 multiple stars, we obtained 4952 new measurements with angular separations in the range 0 ′′ .1 — 14 ′′ and an average accuracy of 0 ′′ .015. The mean error on the position angles is 1 ◦ .0. Most of the position angles were determined without the usual 180 ◦ ambiguity with the application of the direct vector autocorrelation technique and/or by inspection of the Lucky images or the long integration files. We managed to routinely monitor faint systems (m V ≈ 9 − 11) with large magnitude difference (up to ∆m V ≈ 5). We have thus been able to measure 49 systems containing red dwarf stars that had been poorly monitored since their discovery, from which we estimated the stellar masses thanks toGaia measurements. We also measured the magnitude difference of the two components of 318 double stars with an estimated error of 0.2 mag. Except for a few objects that have been discussed, our measurements are in good agreement with the ephemerides computed with published orbital elements, even for the doublestars whose separation is smaller than the diffraction limit. Thanks to good seeing images and with the use of high-contrast numerical filters, we have also been able to obtain 455 measurements with an angular separation smaller than the diffraction limit of our instrumentation, and consistent with those obtained with larger telescopes. Finally, we report 378 measurements of the 296 new double stars that we found in the files obtained during the observations

Measurements of visual binaries with PISCO2 at the Nice 76-cm refractor in 2011-2012

International audienceWe present relative astrometric and photometric measurements of visual binaries made in 2011-2012, withPISCO2 installed at the 76-cm refractor of Côte d’Azur Observatory in Nice (France). Our observing listcontains orbital couples as well as binaries whose motion is still uncertain. Three different techniques havebeen used for obtaining those measurements: Lucky Imaging, Speckle Interferometry and the Direct VectorAutocorrelation method. From our observations of 3136 multiple stars, we obtained 3568 new measurementswith angular separations in the range 0 ′′ .1 — 10 ′′ and an average accuracy of 0 ′′ .016. The mean error on theposition angles is 1 ◦ .7. Most of the position angles were determined without the usual 180 ◦ ambiguity withthe application of the direct vector autocorrelation technique and/or by inspection of the Lucky images or thelong integration files. We managed to routinely monitor faint systems (m V ≈ 9 − 11) with large magnitudedifference (up to ∆m V ≈ 5). We have thus been able to measure many systems containing red dwarf starsthat had been poorly monitored since their discovery. We also measured the magnitude difference of the twocomponents of 326 binaries with an estimated error of 0.2 mag. Except for a few objects that have beendiscussed, our measurements are in a good agreement with the ephemerides computed with published orbitalelements, even for the binaries closer than the diffraction limit. Thanks to good seeing images and with theuse of high-contrast numerical filters, we have also been able to obtain 196 measurements with an angularseparation smaller than the diffraction limit of our instrumentation, and consistent with those obtained withlarger telescopes. We also obtained new measurements of the 15th magnitude multiple system CON37, anddiscovered a faint new double star in its vicinity. Finally, we report 47 measurements of 28 new binaries foundduring our observations