29 research outputs found
Recent developments in optical interferometry data standards
Get PDFA working group on interferometry data standards has been established within IAU Commission 54 (Optical/ Infrared Interferometry). The working group includes members representing the major optical interferometry projects worldwide, and aims to enhance existing standards and develop new ones to satisfy the broad interests of the optical interferometry community. We present the initial work of the group to enhance the OIFITS data exchange standard, and outline the software packages and libraries now available which implement the standard
VLTI status update: a decade of operations and beyond
Full text linkWe present the latest update of the European Southern Observatory's Very
Large Telescope interferometer (VLTI). The operations of VLTI have greatly
improved in the past years: reduction of the execution time; better offering of
telescopes configurations; improvements on AMBER limiting magnitudes; study of
polarization effects and control for single mode fibres; fringe tracking real
time data, etc. We present some of these improvements and also quantify the
operational improvements using a performance metric. We take the opportunity of
the first decade of operations to reflect on the VLTI community which is
analyzed quantitatively and qualitatively. Finally, we present briefly the
preparatory work for the arrival of the second generation instruments GRAVITY
and MATISSE.Comment: 10 pages, 7 figures, Proceedings of the SPIE, 9146-1
Multiple star systems in the Orion nebula
Get PDFThis is the author accepted manuscript. The final fersion is available from EDP Sciences via the DOI in this record.This work presents an interferometric study of the massive-binary fraction in the Orion Trapezium cluster with the recently comissioned GRAVITY instrument. We observed a total of 16 stars of mainly OB spectral type. We find three previously unknown companions for θ1 Ori B, θ2 Ori B, and θ2 Ori C. We determined a separation for the previously suspected companion of NU Ori. We confirm four companions for θ1 Ori A, θ1 Ori C, θ1 Ori D, and θ2 Ori A, all with substantially improved astrometry and photometric mass estimates. We refined the orbit of the eccentric high-mass binary θ1 Ori C and we are able to derive a new orbit for θ1 Ori D. We find a system mass of 21.7 M⊙ and a period of 53 days. Together with other previously detected companions seen in spectroscopy or direct imaging, eleven of the 16 high-mass stars are multiple systems. We obtain a total number of 22 companions with separations up to 600 AU. The companion fraction of the early B and O stars in our sample is about two, significantly higher than in earlier studies of mostly OB associations. The separation distribution hints toward a bimodality. Such a bimodality has been previously found in A stars, but rarely in OB binaries, which up to this point have been assumed to be mostly compact with a tail of wider companions. We also do not find a substantial population of equal-mass binaries. The observed distribution of mass ratios declines steeply with mass, and like the direct star counts, indicates that our companions follow a standard power law initial mass function. Again, this is in contrast to earlier findings of flat mass ratio distributions in OB associations. We excluded collision as a dominant formation mechanism but find no clear preference for core accretion or competitive accretion.Marie Skłodowska-Curie Grant AgreementFCT-PortugalERC Starting Gran
PIONIER: from a Expert mode to an ESO facility instrument
Full text link<p>The PIONIER (Precision Integrated-Optics Near-infrared Imaging ExpeRiment) at the VLT Interferometer instrument was originally a visitor instrument from IPAG (Institut de Planétologie et d’Astrophysique de Grenoble). It is now offered to the ESO community as a facility instrument. As a Visitor monde instrument, it was operated on selected nights by the instrument team/consortium, the goal is now for the Paranal staff to run and monitor the instrument as any other VLT/VLTI instrument. This is done by fully integrating PIONIER in the ESO scheme. I will present here how this was done for the data reduction and the quality assurance of the science data and their related calibrations.</p
Rôle clé du gène Fmr1 dans la photophobie : du patient atteint du syndrome de l’X-Fragile au modèle murin
Full text linkLe syndrome de l’X-Fragile (FXS) est la forme la plus courante de déficience intellectuelle et comportementale héréditaire associée à des troubles de la sensibilité aux stimuli sensoriels (Penagarikano et al., 2007 ; Hagerman et Hagerman, 2015). Sur le plan de visuel, l’intégration est perturbée sur la sensibilité aux contrastes, formes, textures et mouvement (Kogan et al., 2008 ; Farzin et al., 2011). Une étude électrophysiologique (électrorétinogramme - ERG) associée à une évaluation de la perception des contrastes (tests comportementaux), menée chez des patients avec FXS (CLIBIOMAR, ID-RCB 2019-A01015-52) et chez le modèle murin du FXS (souris FMR1y/-), nous a permis de mettre en évidence l’existence d’un trouble visuel de la perception rétinienne (Perche et al., 2018 ; Felgerolle et al., 2019 ; Perche et al., 2021). Chez le patient, outre les conséquences comportementales, notre étude semble démontrer que la dys-sensibilité rétinienne semble se manifester par la présence d’une photophobie avec douleur. La photophobie peut être définie comme une réduction de la sensibilité au contraste provoquée par une lumière éblouissante et une aversion générale pour la lumière (Burstein et al., 2019 ; Chung et al., 2013 ; Noseda et al., 2019). L’existence d’un lien entre les troubles de la discrimination des contrastes et la photophobie suggère qu’elle trouve son origine dans un dysfonctionnement des cellules rétiniennes (Burstein et al., 2019 ; Chung et al., 2013 ; Noseda et al., 2019). L’implication des voies rétiniennes dans la physiopathologie de la photophobie évoquée dans la littérature est confortée par étude de cohorte de patients atteints de FXS (CLIBIOMAR, ID-RCB 2019-A01015-52). En effet, les familles et soignants ont décrit une hypersensibilité avec sensations douloureuses et des comportements d’évitement d’exposition à la lumière dans 55% des cas (11/20) et une « aversion » à la lumière dans 20% des cas (4/20). L’investigation par Short Sensory Profile (SSP) a mis en lumière des comportements significativement altérés sur les paramètres visuels [Sous-score 16.2(6.07) - Probable différence]. Chez le modèle murin, nous avons démontré, en utilisant un Elevated-Plus-Maze modifié, un comportement d’évitement d’exposition à la lumière et de photophobie, à différentes luminances (Alba-Delgado et al., en cours de publication). En effet, l’index d’aversion à la lumière est significativement supérieur chez la souris FMR1y/- comparé au souris sauvage (WT) pour des intensités lumineuses de 120/300 lux [0.155±0.063 versus 0.041±0.070] et 500/1000 lux [0.155±0.051 versus 0.043±0.070]. Ces résultats préliminaires démontrent pour la première fois un phénotype visuel avec nociception dans le FXS. Ce comportement spécifique à des conséquences comportementales majeures pour la vie du patient. Notre objectif est de mieux comprendre les mécanismes physiopathologiques moléculaires et cellulaires impliqués dans cette photophobie à l’aide du modèle murin
Report on the ESO Workshop "20th Anniversary of Science Exploration with UVES"
Full text linkThe UltraViolet-Visual Echelle Spectrograph (UVES) was first offered to the ESO community in 2000. A workhorse covering a vast range of topics from Solar System objects to cosmology, it quickly became one of the most productive instruments at Paranal. For the 20th anniversary of UVES's entering into service, over 100 astronomers from across the world convened in a virtual workshop to celebrate the instrument's achievements and to reframe its role, in a profoundly changed instrumental and scientific landscape, as it enters its 3rd decade of operation at the Very Large Telescope (VLT)
