A5067595855- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Calibration and Measurement Techniques
- Atmospheric Ozone and Climate
- Scientific Research and Discoveries
- Geophysics and Gravity Measurements
- Spectroscopy and Laser Applications
- Geological and Geophysical Studies
- Space Exploration and Technology
- Computational Fluid Dynamics and Aerodynamics
- High-pressure geophysics and materials
- Inertial Sensor and Navigation
- Spacecraft and Cryogenic Technologies
- Urban, Neighborhood, and Segregation Studies
- Advanced Numerical Analysis Techniques
- Aerodynamics and Fluid Dynamics Research
- Adaptive optics and wavefront sensing
- Solar and Space Plasma Dynamics
- Geophysics and Sensor Technology
Université de Toulouse
2016-2022
Université Toulouse III - Paul Sabatier
2016-2022
Centre National de la Recherche Scientifique
2016-2022
Institut de Recherche en Astrophysique et Planétologie
2016-2021
Centre National d'Études Spatiales
2018
Université de Montréal
2010-2017
Polytechnique Montréal
2007
We present improved atmospheric parameters of nearby white dwarfs lying within 20 pc the Sun. The aim current study is to obtain best statistical model least-biased sample dwarf population. A homogeneous analysis local population performed combining detailed spectroscopic and photometric analyses based on atmosphere calculations for various spectral types including DA, DB, DC, DQ, DZ stars. technique applied all stars in our which optical spectra are available. Photometric energy...
We present a spectroscopic survey of 230 white dwarf candidates within 40 pc the Sun from William Herschel Telescope and Gran Telescopio Canarias. All were selected $\textit{Gaia}$ Data Release 2 (DR2) in almost all cases had no prior classifications. find total 191 confirmed dwarfs 39 main-sequence star contaminants. The majority stellar remnants sample are relatively cool ($\langle T_{\rm eff} \rangle$ = 6200 K), showing either hydrogen Balmer lines or featureless spectrum, corresponding...
Context. The signatures of nonlinear effects affecting stellar oscillations are difficult to observe from ground observatories because the lack continuous high-precision photometric data spanning extended enough time baselines. unprecedented quality and coverage provided by Kepler spacecraft offers new opportunities search for these phenomena.
While the near-infrared wavelength regime is becoming more and important for astrophysics there a marked lack of spectrophotometric standard star data that would allow flux calibration such data. Furthermore, calibrating medium- to high-resolution \'echelle spectroscopy challenging even in optical range, because available are often too coarsely sampled. We will provide reference users derive response curves from 300nm 2500nm spectroscopic medium high resolution, including those taken with...
ABSTRACT We present the second of a two-part seismic analysis bright, hot ZZ Ceti stars GD 165 and Ross 548. In this part, we report results detailed searches in parameter space for identifying an optimal model each star that can account well observed periods, while being consistent with spectroscopic constraints derived our first paper. find models target reproduce six periods within ∼0.3% on average. also there is sensitivity core composition 548, practically none 165. Our its thin...
Probing internal properties of white-dwarf stars has been amongst the earliest objectives asteroseismology, following first discovery in late 1960s non-radial pulsations these evolved compact stars. It was swiftly recognized that pulsators could offer new opportunities to unravel their inner structure and dynamics from observed low-degree, low-order gravity ( g -)modes. From early days on, many approaches have attempted fully exploit this potential, with various levels success. Here, we...
Context. The details of the C/O core structure in white dwarf stars has mostly remained inaccessible to technique asteroseismology, despite several attempts carried out past. Aims. We aim re-assess potential asteroseismology for probing chemical stratification cores, light new highly efficient tools recently developed that purpose. Methods. Using forward modeling approach and a parameterization ZZ Ceti stars, we tested situations typical usually limited constraints available, such as small...
We present the discovery and asteroseismic analysis of a new g-mode hot B subdwarf (sdB) pulsator, EC 21494-7018 (TIC 278659026), monitored in TESS first sector using 120-second cadence. The light curve reveals that is sdB pulsator counting up to 20 frequencies associated with independent g-modes. seismic singles out an optimal model solution full agreement measurements provided by spectroscopy (atmospheric parameters derived from atmospheres) astrometry (distance evaluated Gaia DR2...
We present a prescription for parametrizing the chemical profile in core of white dwarfs light recent discovery that pulsation modes may sometimes be deeply confined some cool pulsating dwarfs. Such used as unique probes complicated stratification results from several processes occurred previous evolutionary phases intermediate-mass stars. This effort is part our ongoing quest more credible and realistic seismic models using static, parametrized equilibrium structures. Inspired by successful...
Abstract An interesting opportunity offered by the detection of stellar oscillations is possibility to infer internal rotation rate a star through so-called rotational splittings. Such seismic measurements remained rather scarce for hot B subdwarf (sdB) stars until advent space observations with Kepler spacecraft. Nowadays, however, number have become available, offering glimpse on global properties sdB stars. Here, we briefly discuss what asteroseismology starts reveal these We also make...
Asteroseismology is a powerful tool to unravel the chemical composition and stratification inside white dwarfs, as recently achieved by Giammichele et al. (2018, Nature, 554, 73) for pulsating DB star KIC 08626021. However, Timmes ApJ, 867, L30) pointed out that neglecting effects of neutrino cooling, such in models used study, could significantly impact derived seismic solution compromise conclusions drawn upon it. In this context, we perform complete reevaluation uncovered 08626021, using...
We present the first of a two-part seismic analysis two bright hot ZZ Ceti stars GD 165 and Ross 548. In this part, we report results frequency extraction exercises based on time-series data sets exceptional quality. uncovered up to 13 independent pulsation modes in 165, regrouped into six main multiplets. These include 9 secure (signal-to-noise ratio, S/N > 4) detections 4 possible ones (4 ≥ 3). Likewise, isolated 11 548 (9 2 detections), also 6 The multiplet structure is likely caused by...
This paper presents a scheme that combines multiresolution curve editing with linear constraints: thickness and camber. framework allows to perform manipulation of piecewise polynomial B-spline curves, while specifying satisfying various constraints on the curves. An easy computable technique is investigated for purpose airfoil design as novel tool generation optimization 2D wing profile. Thickness camber imposed at several sections profile are incorporated into this freeform generating...
We present a detailed asteroseismological study of the pulsating white dwarf R548 based on fits to newly detected periods and use forward method. In this first part, we concentrate frequency extraction analysis. Based an unexploited CFHT/LAPOUNE broadband photometric campaign high S/N, are able obtain finer spectrum uncover two triplets, doublets, singlets. The low-amplitude “simple” pulsator is ideal candidate for carrying complete analysis within framework adiabatic approximation optimized...
Abstract We explore quantitatively the low but sufficient sensitivity of oscillation modes to probe both core composition and details chemical stratification pulsating white dwarfs. Until recently, applications asteroseismic methods dwarfs have been far few, generally suffered from an insufficient exploration parameter space. To remedy this situation, we apply same double-optimization technique that has used quite successfully in context hot B subdwarfs. Based on frequency spectrum dwarf...
Abstract We present a brief progress report in our quest for deriving seismic models of pulsating white dwarfs that can account simultaneously all the observed periods at precision observations. point out this is possible from pratical view only if parametrized are used to complement evolutionary models. adopt double optimization procedure insures best model parameter space found objectively and automatically. Our ultimate goal be able exquisite period data gathered with Kepler Kepler-2 on...
Using the forward modeling approach and a new parameterization for core chemical stratification in ZZ Ceti stars, we test several situations typical of usually limited constraints available, such as small numbers observed independent modes, to carry out asteroseismology these stars. We find that, even with number (in particular, location steep transitions expected oxygen profile) can be determined quite precisely due significant sensitivity some confined modes partial reflexion (trapping)...
We present the results of asteroseismic analysis hydrogen-deficient white dwarf PG 0112+104 from $Kepler$-2 field. Our seismic procedure using forward method based on physically sound, static models, includes new core parameterization leading us to reproduce periods this star near precision observations. This fit outperforms current state-of-the-art standards by order magnitudes. precisely establish internal structure and unravel inner C/O stratification its core. opens up interesting...
DA-type white dwarfs account for 80% of all and represent, most them, the ultimate outcome typical evolution low-to-intermediate mass stars. Their internal chemical stratification is strongly marked by passed, often uncertain, stellar processes that occurred during helium (core shell) burning phases, i.e., from horizontal branch through AGB post-AGB stages. Pulsating dwarfs, in particular "cool" ZZ Ceti variables, offer an outstanding opportunity to dig into these stars fully exploiting...
While the near-infrared wavelength regime is becoming more and important for astrophysics there are few spectrophotometric standard star data available to flux calibrate such data. On other hand calibrating high-resolution spectra a challenge even in optical range, because often too coarsely sampled. We describe method obtain reference derived from stellar model atmospheres, which allow users derive response curves 300 nm 2500 also spectra. verified that they provide an appropriate...