P. Mathias
A5036648235- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Gamma-ray bursts and supernovae
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- History and Developments in Astronomy
- Traffic control and management
- Vehicle emissions and performance
- Traffic Prediction and Management Techniques
- Insect Pest Control Strategies
- Nematode management and characterization studies
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Inertial Sensor and Navigation
- Insect behavior and control techniques
- Insect-Plant Interactions and Control
- Geophysics and Sensor Technology
- Vehicular Ad Hoc Networks (VANETs)
- Autonomous Vehicle Technology and Safety
- Transportation Safety and Impact Analysis
- Astrophysical Phenomena and Observations
Institut de Recherche en Astrophysique et Planétologie
2014-2024
Centre National de la Recherche Scientifique
2011-2023
Université de Toulouse
2011-2023
Observatoire Midi-Pyrénées
2009-2023
Université Toulouse III - Paul Sabatier
2009-2023
Centre National d'Études Spatiales
2022
Observatoire de la Côte d’Azur
2002-2017
École Nationale d'Ingénieurs de Tarbes
2014
FH Aachen
2013
Laboratoire d'Astrophysique de Bordeaux
2009-2011
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).
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.
Oscillations of the Sun have been used to understand its interior structure. The extension similar studies more distant stars has raised many difficulties despite strong efforts international community over past decades. CoRoT (Convection Rotation and Planetary Transits) satellite, launched in December 2006, now measured oscillations stellar granulation signature three main sequence that are noticeably hotter than sun. oscillation amplitudes about 1.5 times as large those Sun; is up high....
The Kepler spacecraft is providing time series of photometric data with micromagnitude precision for hundreds A-F type stars. We present a first general characterization the pulsational behaviour stars as observed in light curves sample 750 candidate propose three main groups to describe variety pulsating stars: gamma Dor, delta Sct, and hybrid assign 63% our one groups, identify remaining part rotationally modulated/active stars, binaries, different spectral type, or that show no clear...
Observations of the pulsations stars can be used to infer their interior structure and test theoretical models. The main-sequence γ Doradus (Dor) δ Scuti (Sct) with masses 1.2–2.5 M☉ are particularly useful for these studies. Dor pulsate in high-order g-modes periods order 1 day, driven by convective blocking at base envelope convection zone. Sct low-order g- p-modes 2 hr, κ mechanism operating He ii ionization Theory predicts an overlap region Hertzsprung–Russell diagram between instability...
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.
<i>Context. <i/> <i>Aims. <i/>This work presents the results obtained by CoRoT on HD 50844, only <i>δ<i/> Sct star observed in initial run (57.6 d). The aim of these observations was to investigate and characterize for first time pulsational behaviour a star, when at level precision with much better duty cycle than from ground.<i>Methods. <i/>The 140 016 datapoints were analysed using independent approaches (SigSpec software different iterative sine-wave fittings) several checks performed...
<i>Context. <i/> <i>Aims. <i/>In this work, we describe the pipeline for fast supervised classification of light curves observed by CoRoT exoplanet CCDs. We present results obtained first four measured fields, which represent a one-year in-orbit operation.<i>Methods. <i/>The basis adopted methodology has been described in detail previous paper, as is its application to OGLE database. Here, modifications algorithms and training set optimize performance when applied data.<i>Results....
SUMMARY In a field experiment on infested sandland from 1955 to 1967, numbers of Heterodera avenae increased only in 1957 and then decreased under both continuous rotational spring oats (1955‐62) subsequently barley (1963‐67). Fluctuations Pratylenchus neglectus Trichodorus primitivus were recorded 1963 1967. Cereal grain yields generally unsatisfactory, but consistently higher for cereals grown rotation rather than continuously. Extra nitrogen fertilizer gave slightly improved with...
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...
Direct imaging of the HR 8799 system was a major achievement in study exoplanets. is γ Doradus variable and asteroseismology can provide an independent constraint on inclination. Using 650 high signal-to-noise, high-resolution, full visual wavelength spectroscopic observations obtained over two weeks at Observatoire de Haute Provence with SOPHIE spectrograph, we find that main frequency radial velocity data 1.9875 day−1. This corresponds to as found previous photometric observations. FAMIAS...
Context. Be stars are rapidly rotating with a circumstellar decretion disk. They usually undergo pressure and/or gravity pulsation modes excited by the κ-mechanism, i.e. an effect of opacity iron-peak elements in envelope star. In Milky Way, p-modes observed that hotter than or equal to B3 spectral type, while g-modes at B2 type and cooler.
Context. The mass-loss mechanism of cool massive evolved stars is poorly understood. proximity Betelgeuse makes it an appealing target to study its atmosphere, map the shape envelope, and follow structure wind from photosphere out interstellar medium.
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.
Aims. The aim of this work was to use a multi-approach technique derive the most accurate values possible physical parameters δ Sct star HD 174966, which observed with CoRoT satellite. In addition, we searched for periodic pattern in frequency spectra goal using it determine mean density star.
The distance of galactic Cepheids can be derived through the interferometric Baade-Wesselink method. measurements lead to angular diameter estimations over whole pulsation period, while stellar radius variations deduced from integration velocity. latter is linked observational velocity line profiles by so-called projection factor p. knowledge p currently an important limiting for this method determination. A self-consistent and time-dependent model star δ Cep computed in order study...
We present the first results of a 2-year high-resolution spectroscopy campaign 59 candidate Gamma Doradus stars which were mainly discovered from HIPPARCOS astrometric mission. More than 60 % line profile variations can be interpreted as due to pulsation related stars. For all we also derived projected rotation velocity (up more 200 km\s). The amplitude ratios 2K/Delta m for main frequency are in range 35 - 96 (km\s)\mag. Less 50 candidates possible members binary systems, with 20 being...
Context. Interferometry can provide spatially resolved observations of massive star binary systems and their colliding winds, which thus far have been studied mostly with unresolved observations.
Aims.We present a mode identification based on new high-resolution time-series spectra of the non-radially pulsating δ Scuti star FG Vir (HD 106384, , A5V). From 2002 February to June global Delta Network (DSN) campaign, utilizing spectroscopy and simultaneous photometry has been conducted for in order provide theoretical pulsation model. In this campaign we have acquired 969 Echelle covering 147 h at six observatories.
Aims.We investigate the origin of emission Herbig Ae star HD 104237 on Astronomical Unit (AU) scales.
Context: We present the results of an extensive ground-based photometric and spectroscopic campaign on gamma Dor CoRoT target HD49434. This was preparatory to satellite observations, which took place from October 2007 March 2008. Results: The frequency analysis clearly shows presence four frequencies in 0.2-1.7 c/d interval, as well six 5-12 domain. low are typical for variables while high common delta Sct pulsators. propose 2.666 a possible rotational frequency. All modes, identification...