A5039093383- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Gamma-ray bursts and supernovae
- History and Developments in Astronomy
- Astronomical and nuclear sciences
- Galaxies: Formation, Evolution, Phenomena
- Scientific Research and Discoveries
- Fault Detection and Control Systems
- Nuclear physics research studies
- Geophysics and Gravity Measurements
- Astrophysical Phenomena and Observations
- High-pressure geophysics and materials
- Adaptive Control of Nonlinear Systems
- Geomagnetism and Paleomagnetism Studies
- Stability and Control of Uncertain Systems
- Space Satellite Systems and Control
- Spacecraft Dynamics and Control
- Calibration and Measurement Techniques
- Cosmology and Gravitation Theories
- Atmospheric Ozone and Climate
- Dynamics and Control of Mechanical Systems
Centre National de la Recherche Scientifique
2015-2024
University of Geneva
2015-2024
Université de Toulouse
2015-2024
Institut de Recherche en Astrophysique et Planétologie
2013-2024
Université Toulouse III - Paul Sabatier
2006-2019
Thales (Germany)
2012-2019
Leonardo (United States)
2009-2019
Observatoire Midi-Pyrénées
2000-2016
Thales (United Kingdom)
2009-2014
Global Social Observatory
2004-2013
[abridged] Many topical astrophysical research areas, such as the properties of planet host stars, nature progenitors different types supernovae and gamma ray bursts, evolution galaxies, require complete homogeneous sets stellar models at metallicities in order to be studied during whole cosmic history. We present here a first set for solar metallicity, where effects rotation are accounted way. computed grid 48 evolutionary tracks, both rotating non-rotating, Z=0.014, spanning wide mass...
Aims.We propose the Wind of Fast Rotating Massive Stars scenario to explain origin abundance anomalies observed in globular clusters.
Aims. We study the impact of a subsolar metallicity on various properties non-rotating and rotating stars, such as surface velocities abundances, lifetimes, evolutionary tracks, scenarios.
The availability of asteroseismic constraints for a large sample stars from the missions CoRoT and Kepler paves way various statistical studies seismic properties stellar populations. In this paper, we evaluate impact rotation-induced mixing thermohaline instability on global parameters at different stages evolution Zero Age Main Sequence to Thermally Pulsating Asymptotic Giant Branch distinguish We present grid evolutionary models four metallicities (Z = 0.0001, 0.002, 0.004, 0.014) in mass...
We present a model for the concurrent formation of globular clusters (GCs) and supermassive stars (SMSs, $>10^3\,{\rm M}_\odot$) to address origin HeCNONaMgAl abundance anomalies in GCs. GCs form converging gas flows accumulate low-angular momentum gas, which accretes onto protostars. This leads an adiabatic contraction cluster increase stellar collision rate. A SMS can via runaway collisions if reaches sufficiently high density before two-body relaxation halts contraction. condition is met...
Unusually high N/O abundance ratios were recently reported for a very compact, intensively star-forming object GN-z11 at $z=10.6$ from JWST/NIRSpec observations. We present an empirical comparison with the C, N, and O in Galactic globular clusters (GCs) over large metallicity range. show that hot hydrogen-burning nucleosynthesis within supermassive stars (SMS) formed through runaway collisions can consistently explain observed abundances ratio GCs. This suggests proto-globular cluster...
The Sun's rotation profile and lithium content have been difficult to understand in the context of conventional models stellar evolution. Classical hydrodynamic predict that solar interior must rotate highly differentially, disagreement with observations. It has recently shown internal waves produced by convection solar-type stars produce an asymmetric, shear layer oscillation, similar Earth's quasi-biennial leads efficient angular momentum redistribution from core envelope. We present...
The observations of carbon isotopic ratios in evolved stars suggest that nonstandard mixing is acting low-mass as they are ascending the red giant branch. We propose a simple consistent mechanism, based on most recent developments description rotation-induced reported by Zahn 1992, which simultaneously accounts for low 12C/13C globular cluster and field Population II giants lithium abundances metal-poor stars. It also leads to destruction 3He produced main sequence This should both naturally...
Aims.Numerous spectroscopic observations provide compelling evidence for a non-canonical mixing process that modifies the surface abundances of Li, C and N low-mass red giants when they reach bump in luminosity function. Eggleton collaborators have proposed molecular weight inversion created by 3He(3He, 2p)4He reaction may be at origin this mixing, relate it to Rayleigh-Taylor instability. We argue one is actually dealing with double diffusive instability referred as thermohaline convection...
Galactic globular cluster (GC) stars exhibit abundance patterns which are not shared by their field counterparts, In the framework of widely accepted "self-enrichment" scenario for GCs, we present a new method to derive Initial Mass Function (IMF) polluter stars, using observed O/Na distribution. We focus on NGC 2808, GC largest sample O and Na determinations is presently available. consider two classes possible "culprits" : massive Asymptotic Giant Branch (AGB) (4-9 Msun) winds (WMS) in...
(abridged) Numerous spectroscopic observations provide compelling evidence for non-canonical processes that modify the surface abundances of low- and intermediate-mass stars beyond predictions standard stellar theory. We study effects thermohaline instability rotation-induced mixing in 1-4 Msun range at solar metallicity. present evolutionary models by considering both interior. discuss these on chemical properties from zero age main sequence up to end second dredge-up early-AGB AGB tip...
Aims. We analyse the effects of a first generation fast rotating massive stars on dynamical and chemical properties globular clusters. Methods. use stellar models stars, losing mass through slow mechanical equatorial winds to produce material rich in H-burning products. propose that with high Na low O abundances (hereafter anomalous stars) are formed from matter made individual interstellar matter. The proportion wind is fixed order reproduce observed Li-Na anticorrelation NGC 6752. Results....
<i>Context. <i/>To alleviate the discrepancy between prediction of primordial lithium abundance in universe and abundances observed Pop II dwarfs subgiant stars, it has been suggested that stars observable today have undergone photospheric depletion lithium.<i>Aims. identify cause this depletion, is important to accurately establish behaviour with effective temperature evolutionary phase. Stars globular clusters are ideal objects for such an analysis, because relative stellar parameters can...
Context. The self-enrichment scenario for globular clusters (GC) requires large amounts of residual gas after the initial formation first stellar generation. Recently, we found that supernovae may not be able to expel gas, as required explain their present-day gas-free state, and suggested a sudden accretion onto dark remnants at stage when type II have ceased plausibly lead fast expulsion.
We present dense grids of stellar models suitable for comparison with observable quantities measured great precision, such as those derived from binary systems or planet-hosting stars. computed new Geneva without rotation at metallicities Z=0.006, 0.01, 0.014, 0.02, 0.03 and 0.04 (i.e. [Fe/H] -0.33 to +0.54) mass in small steps 0.5 3.5 Msun. Great care was taken the procedure interpolating between tracks order compute isochrones. Several properties our are presented a function metallicity....
We investigate the magnetic field at surface of 48 red giants selected as promising for detection Stokes V Zeeman signatures in their spectral lines. use spectropolarimeters Narval and ESPaDOnS to detect circular polarization within photospheric absorption lines our targets least-squares deconvolution (LSD) method. also measure classical S-index activity indicator, stellar radial velocity. To infer evolutionary status interpret results, we state-of-the-art models with predictions convective...
We study the predicted rotational evolution of solar-type stars from pre-main sequence to solar age with 1D rotating evolutionary models including physical ingredients. computed an external stellar wind torque and internal transport angular momentum following method Maeder Zahn code STAREVOL. explored different formalisms prescriptions available literature. tested predictions against recent period data extensive photometric surveys, lithium abundances solar-mass in young clusters,...
Star clusters are fundamental units of stellar feedback and unique tracers their host galactic properties. In this review, we will first focus on constituents, i.e.\ detailed insight into populations surrounding ionised, warm, neutral, molecular gas. We, then, move beyond the Local Group to review star cluster at various evolutionary stages, in diverse environmental conditions accessible local Universe. At high redshift, where for formation evolution more extreme, only able observe...