D. Mourard
A5043777028- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Adaptive optics and wavefront sensing
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Advanced optical system design
- Astrophysical Phenomena and Observations
- Advanced Measurement and Metrology Techniques
- Radio Astronomy Observations and Technology
- History and Developments in Astronomy
- Optical Coherence Tomography Applications
- Optical Systems and Laser Technology
- Optical Polarization and Ellipsometry
- Optical measurement and interference techniques
- Calibration and Measurement Techniques
- Geophysics and Gravity Measurements
- Semiconductor Lasers and Optical Devices
- Astrophysics and Cosmic Phenomena
- CCD and CMOS Imaging Sensors
- Advanced Optical Sensing Technologies
- Advanced Fiber Optic Sensors
- Solar and Space Plasma Dynamics
- Spectroscopy and Laser Applications
Centre National de la Recherche Scientifique
2015-2024
Observatoire de la Côte d’Azur
2015-2024
Université Côte d'Azur
2013-2023
Lagrange Laboratory
2012-2020
Collège de France
2016
Institut de Biologie Valrose
2011
Observatoire de Lyon
2010
Université Claude Bernard Lyon 1
2010
Capgemini (Netherlands)
2004-2007
Centre de Gestion Scientifique
2006
Context.Optical long-baseline interferometry is moving a crucial step forward with the advent of general-user scientific instruments that equip large aperture and hectometric baseline facilities, such as Very Large Telescope Interferometer (VLTI).
When observed with optical long-baseline interferometers, components of a binary star that are sufficiently separated produce their own interferometric fringe packets; these referred to as packet (SFP) binaries. These SFP binaries can overlap in angular separation the regime systems resolvable by speckle interferometry at single, large-aperture telescopes and provide additional measurements for preliminary orbits lacking good phase coverage, help constrain elements already established...
Aims.In this paper, we present an innovative data reduction method for single-mode interferometry. It has been specifically developed the AMBER instrument, three-beam combiner of Very Large Telescope Interferometer, but it can be derived any interferometer.
<i>Context. <i/>Among optical stellar interferometers, the CHARA Array located at Mt Wilson in California offers potential of very long baselines (up to 330 m) and prospect coupling multiple beam combiners. This paper presents principle measured performance VEGA, Visible spEctroGraph polArimeter installed September 2007 coherent focus array.<i>Aims. <i/>With 0.3 ms arc spatial resolution up spectral resolution, VEGA intends measure fundamental parameters stars, study activities image analyze...
Photonics offer numerous functionalities that can be used to realize astrophotonic instruments. The most spectacular example date is the ESO Gravity instrument at Very Large Telescope in Chile. Integrated devices stand critical advantages for development, including extreme miniaturization, as well integration, superior thermal and mechanical stabilization owing small footprint, high replicability offering cost savings. Numerous technologies have been developed address shortcomings of...
In long baseline interferometry, the raw fringe contrast must be calibrated to obtain true visibility and then those observables that can interpreted in terms of astrophysical parameters. The selection suitable calibration stars is crucial for obtaining ultimate precision interferometric instruments like VLTI. We have developed software SearchCal builds an evolutive catalog as calibrators within any given user-defined angular distance magnitude around scientific target. present first version...
Context.The ratio of pulsation to radial velocity (the projection factor) is currently limiting the accuracy Baade-Wesselink method, and in particular its interferometric version recently applied several nearby Cepheids.
Context. In long-baseline interferometry, images or astrophysical parameters are obtained from the raw fringe contrast after a careful calibration process. We have already developed software (SearchCal) to select suitable bright stars (V ≤ 10; K 5.0) for obtaining ultimate precision of current interferometric instruments like VLTI. With expected gain in sensitivity AMBER and PRIMA on VLTI, need fainter calibrators should now be adressed.
Aims. The rapidly rotating Be star ϕ Persei was spun up by mass and angular momentum transfer from a now stripped-down, hot subdwarf companion. Here we present the first high resolution images of made possible new capabilities in long-baseline interferometry at near-IR visible wavelengths. We analyzed these to search for companion, determine binary orbit, stellar masses, fluxes, examine geometrical kinematical properties outflowing disk surrounding star.
The recent VINCI/VLTI observations presented in Paper I have nearly doubled the total number of available angular diameter measurements Cepheids.Taking advantage significantly larger color range covered by these observations, we derive present paper high precision calibrations surface brightness-color relations using exclusively Cepheid observations.These empirical laws make it possible to determine distance Cepheids through a Baade-Wesselink type technique.The least dispersed are based on...
Aims. We present the first NIR spectro-interferometry of LBV η Carinae. The observations were performed with AMBER instrument ESO Very Large Telescope Interferometer (VLTI) using baselines from 42 to 89 m. aim this work is study wavelength dependence Car's optically thick wind region a high spatial resolution 5 mas (11 AU) and spectral resolution.
The young stellar object MWC 297 is an embedded B1.5Ve star exhibiting strong hydrogen emission lines and a near-infrared continuum excess. This has been observed with the VLT interferometer equipped AMBER instrument during its first commissioning run. AMBER/VLTI currently only near infrared that can observe spectrally dispersed visibilities. spatially resolved in visibility of as well Brγ line where decreases to . change wavelength be interpreted by presence optically thick disk responsible...
Context. To progress in the understanding of evolution massive stars one needs to constrain mass-loss and determine phenomenon responsible for ejection matter an its reorganization circumstellar environment Aims. In order test various mass-ejection processes, we probed geometry kinematics dust gas surrounding A[e] supergiant HD 62623. Methods. We used combined high spectral spatial resolution covered by VLTI/AMBER instrument. Thanks a new multiwavelength optical/IR interferometry imaging...
Context. The G-type star GJ504A is known to host a 3–35 M Jup companion whose temperature, mass, and projected separation all contribute making it test case for planet formation theories atmospheric models of giant planets light brown dwarfs. Aims. We aim at revisiting the system age, architecture, physical chemical properties using new complementary interferometric, radial-velocity, high-contrast imaging data. Methods. used CHARA interferometer measure GJ504A’s angular diameter obtained an...
Metal-poor halo stars are important astrophysical laboratories that allow us to unravel details about many aspects of astrophysics, including the chemical conditions at formation our Galaxy, understanding processes diffusion in stellar interiors, and determining precise effective temperatures calibration colour-effective temperature relations. To address any these issues fundamental properties must first be determined. HD 140283 is closest brightest metal-poor Population II star (distance =...
Abstract Large stellar surveys of the Milky Way require validation with reference to a set ‘benchmark’ stars whose fundamental properties are well determined. For metal-poor benchmark stars, disagreement between spectroscopic and interferometric effective temperatures has called reliability temperature scale into question. We present new measurements three HD 140283, 122563, 103095, from which we determine their temperatures. The angular sizes all were determined observations PAVO beam...
We report the angular diameter measurements of seven classical Cepheids, X Sgr, η Aql, W ζ Gem, β Dor, Y Oph and Car that we have obtained with VINCI instrument, installed at ESO's VLT Interferometer (VLTI).We also present reprocessed archive data FLUOR/IOTA instrument on in order to improve phase coverage our observations.We obtain average limb darkened values θ040 mas, θ LD [ Car] = 2.988 ± 0.012 mas.For four these stars, Car, detect pulsational variation their diameter.This enables us...
The cross correlation method (hereafter CC) is widely used to derive the radial velocity curve of Cepheids when signal noise spectra low. However, if it with wrong projection factor, might introduce some biases in Baade-Wesselink BW) methods determining distance Cepheids. In addition, affect average value (or gamma-velocity) important for Galactic structure studies. We aim a period-projection factor relation Pp) appropriate be together CC method. Moreover, we investigate whether can explain...
Context.The projection factor is a key quantity for the interferometric Baade-Wesselink (hereafter IBW) and surface-brightness SB) methods of determining distance Cepheids. Indeed, it allows consistent combination angular linear diameters star.
Context. Five different physical processes might be responsible for the formation of decretion disks around Be stars: fast rotation star, stellar pulsations, binarity, winds, and magnetic fields. Our observations indicate that seems to produce a disk in Keplerian rotation, at least specific case two stars observed. We do not know if this observational result is generality or not.
γCas is the prototypical classical Be star and best known for its variable hard X-ray emission. To elucidate reasons this emission, we mounted a multiwavelength campaign in 2010 centered around 4 XMM observations. The observational techniques included long baseline optical interferometry (LBOI), monitoring by an Automated Photometric Telescope Halpha Because gamma Cas also to be binary, measured radial velocities redetermined period as 203.55+/-0.2 days eccentricity near zero. LBOI...
Accurate stellar parameters are needed in numerous domains of astrophysics. The position stars on the H-R diagram is an important indication their structure and evolution, it helps improve models. Furthermore, age mass hosting planets required elements for studying exoplanetary systems. We aim at determining accurate a set 18 bright exoplanet host potential from interferometric measurements, photometry, Using VEGA/CHARA interferometer, we measured angular diameters stars, ten which...
M dwarfs are an ideal laboratory for hunting Earth-like planets, and the study of chromospheric activity is important part this task. On one hand, according to short-term their high levels magnetic can affect habitability make it difficult detect exoplanets orbiting around them. other however, long-term studies show whether or not these stars exhibit cyclical behaviour in activity, facilitating detection planets periods low activity. The be detected by studying several spectral lines...