A5080252910- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Nuclear physics research studies
- Astronomical Observations and Instrumentation
- Astronomical and nuclear sciences
- High-pressure geophysics and materials
- Solar and Space Plasma Dynamics
- Fluid Dynamics Simulations and Interactions
- Astrophysical Phenomena and Observations
- Nuclear Physics and Applications
- Methane Hydrates and Related Phenomena
- Aeolian processes and effects
- Atomic and Molecular Physics
- Scientific Research and Discoveries
- Spacecraft and Cryogenic Technologies
- Nuclear reactor physics and engineering
- Planetary Science and Exploration
- Pulsars and Gravitational Waves Research
- International Science and Diplomacy
- Educational Leadership and Practices
- Gas Dynamics and Kinetic Theory
- Radioactive Decay and Measurement Techniques
Université Libre de Bruxelles
2016-2025
Max Planck Institute for Astrophysics
2012-2018
Institute of Astronomy
2018
Fund for Scientific Research
2017-2018
Max Planck Society
2017
Monash University
2002-2010
Space Telescope Science Institute
1997-2002
Université de Montpellier
2002
Laboratoire d'Informatique de Grenoble
2000
Université Joseph Fourier
1997-1999
We explore the final fates of massive intermediate-mass stars by computing detailed stellar models from zero-age main sequence until near end thermally pulsing phase. These super-asymptotic giant branch (super-AGB) and AGB star are in mass range between 5.0 10.0 M⊙ for metallicities spanning Z = 0.02–0.0001. probe limits Mup, Mn Mmass, minimum masses onset carbon burning, formation a neutron iron core-collapse supernovae, respectively, to constrain white dwarf/electron-capture supernova...
Close-in planets are in jeopardy, as their host stars evolve off the main sequence (MS) to subgiant and red giant phases. In this paper, we explore influences of stellar mass (in range 1.5–2 M☉), mass-loss prescription, planet (from Neptune up 10 Jupiter masses), eccentricity on orbital evolution parent become subgiants giants. We find that engulfment along branch is not very sensitive or rates adopted calculations, but quite planetary mass. The initial separations for increases with...
Proton-<a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mi>γ</a:mi></a:math> coincidences from <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mo>(</b:mo><b:mi>d</b:mi><b:mo>,</b:mo><b:mi>p</b:mi><b:mo>)</b:mo></b:mrow></b:math> reactions between a <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mmultiscripts><c:mi>Ni</c:mi><c:mprescripts/><c:none/><c:mn>66</c:mn></c:mmultiscripts></c:math> beam and deuterated polyethylene target have been analyzed with the...
This paper extends our previous study of planet/brown dwarf accretion by giant stars to solar mass located on the red branch. The model assumes that planet is dissipated at bottom convective envelope star. giant's evolution then followed in detail. We analyze effects different rates and initial conditions. computations indicate process accompanied a substantial expansion star, case high rates, hot burning can be activated. possible observational signatures accompany engulfing are also...
Context.Massive AGB (hereafter super-AGB or SAGB) stars ignite carbon off-center and have initial masses ranging between , the minimum mass for ignition, Mmas formation of an iron core collapse supernova. In this interval, more massive than will undergo electron capture supernova (EC-SN).
We present new computations of the evolution solar metallicity stars in mass range . This first paper a series focuses on propagation carbon burning flame front and provides detailed analysis structural up to formation neon-oxygen core. Our calculations which do not include overshooting indicate that off-center ignition is restricted small between 9.0 11.3 The chemical imprints second dredge-ups surface composition are analyzed compared "standard" less massive stars. It results that, aside...
We have computed detailed evolution and nucleosynthesis models for super massive AGB stars over the mass range 6.5-9.0 Msun in divisions of 0.5 with metallicities Z=0.02, 0.008 0.004. These calculations, which we find third dredge-up hot bottom burning, fill gap between existing low intermediate-mass star high that become supernovae. For considered metallicities, composition yields is largely dominated by thermodynamic conditions at base convective envelope rather than pollution arising from...
<i>Aims. <i/>We present the first simulations of full evolution super-AGB stars through entire thermally pulsing AGB phase. We analyse their structural and evolutionary properties determine SAGB yields. <i>Methods. <i/>Stellar models various initial masses metallicities were computed using standard physical assumptions which prevents third dredge-up from occurring. A postprocessing nucleosynthesis code was used to compute yields, quantify effect (3DUP), assess uncertainties associated with...
We review the lives, deaths and nucleosynthetic signatures of intermediate mass stars in range approximately 6.5-12 Msun, which form super-AGB near end their lives. examine critical boundaries both between different types massive white dwarfs (CO, CO-Ne, ONe) supernovae discuss relative fraction that life as either an ONe dwarf or a neutron star (or ONeFe dwarf), after undergoing electron capture supernova. also contribution other potential single-star channels to electron-capture...
The unparalleled photometric data obtained by NASA's Kepler space telescope led to an improved understanding of red giant stars and binary stars. Seismology allows us constrain the properties giants. In addition eclipsing binaries, eccentric non-eclipsing exhibiting ellipsoidal modulations, have been detected with Kepler. We aim study systems containing a star derive parameters primary component. apply asteroseismic techniques determine masses radii component each system. For selected...
We present a new grid of stellar models and nucleosynthetic yields for super-AGB stars with metallicities Z = 0.001 0.0001, applicable use within galactic chemical evolution models. Contrary to more metal-rich where hot bottom burning is the main driver surface composition, in these lower metallicity effect third dredge-up corrosive second also have strong impact on yields. These metal-poor very create large amounts 4He, 13C, 14N 27Al as well heavy magnesium isotopes 25Mg 26Mg. There...
Context. Results from observations report a growing number of metal-poor stars showing an abundance pattern midway between the s - and r -processes. These so-called r/s-stars raise need for intermediate neutron capture process ( i -process), which is thought to result ingestion protons in convective helium-burning region, but whose astrophysical site still largely debated. Aims. We investigate whether -process during asymptotic giant branch (AGB) phase low-metallicity low-mass can develop it...
Context. The observed surface abundance distributions of carbon-enhanced metal-poor (CEMP) r / s stars suggest that these could have been polluted by an intermediate neutron capture process (the so-called i -process) occurring at densities between the - and -processes. Triggered ingestion protons inside a convective He-burning zone, -process be hosted in several sites, promising one being early AGB phase low-mass, low-metallicity stars. remains affected however many uncertainties, including...
Aims.In this paper we study the effects of rotation in low-mass, low-metallicity RGB stars.
We study the response of structure an asymptotic giant branch (AGB) star to accretion a brown dwarf or planet in its interior. In particular, we examine case which spirals-in, and accreted matter is deposited at base convective envelope thin radiative shell surrounding hydrogen burning shell. our spherically symmetric simulations, explore effects different rates follow two scenarios amounts injected mass are equal ∼ 0.01 0.1 M⊙. The calculations show that for high (Ṁacc= 10−4M⊙yr −1),...
<i>Context. <i/>Recent progress and constraints brought by helio asteroseismology call for a better description of stellar interiors an accurate rotation-driven mechanisms in stars.<i>Aims. <i/>We present detailed analysis the main physical processes responsible transport angular momentum chemical species radiative regions rotating stars. We focus on cases where meridional circulation shear-induced turbulence all that are included simulations (i.e., no either internal gravity waves nor...
Alongside the slow (s) and rapid (r) neutron capture processes, an intermediate process (i-process) is thought to exist. It happens when protons are mixed in a convective helium-burning zone, referred as proton ingestion event (PIE). A possible astrophysical site asymptotic giant branch (AGB) phase of low-mass low-metallicity stars. We provide i-process yields grid AGB stars experiencing PIEs. computed 12 models with initial masses 1, 2, 3 $M_{\odot}$ metallicities [Fe/H] $=-3.0$, $-2.5$...
Context. The intermediate neutron capture process ( i -process) can develop during proton ingestion events (PIE), potentially the early stages of low-mass low-metallicity asymptotic giant branch (AGB) stars. Aims. We examine impact overshoot mixing on triggering and development -process nucleosynthesis in AGB stars various initial masses metallicities. Methods. computed stellar models, with 1, 2, 3, 4 M ⊙ metallicities −2.5 ≤ [Fe/H] 0 range, using evolution code STAREVOL a network 1160...
(abridge version) The evolution of population III stars (Z=0) is followed from the pre-main sequence phase up to AGB for intermediate-mass and C ignition in more massive stars...We find that, thanks development mixing episodes (carbon injections) at beginning phase, carbon abundance 1, 1.5, 2, 3, 4 5Mo models significantly increased envelope. This process then allows low- achieve a ``standard'' thermally pulsing phase... In 7Mo model, CNO envelope following second dredge-up so large that...
In a recent study, individual parallaxes were determined for many stars of the Taurus-Auriga T association that are members same moving group. We use these new to re-address issue relationship between classical Tauri (CTTSs) and weak-emission line (WTTSs). With available spectroscopic photometric information 72 or stellar systems among objects with known parallaxes, we derived reliable photospheric luminosities, mainly from Ic magnitude objects. then studied mass age distributions sample,...
In recent years much interest has been shown in the process of thermohaline mixing red giants. low- and intermediate-mass stars this mechanism first activates at position bump luminosity function, identified as a likely candidate for driving slow inferred to occur these stars. One particularly important consequence process, which is driven by molecular weight inversion, destruction lithium. We show that degree lithium destruction, or some cases production, extremely sensitive numerical...
The theoretical and observed populations of pre-cataclysmic variables (pre-CVs) are dominated by systems with low-mass white dwarfs (WDs), while the WD masses in CVs typically high. In addition, space density is found to be significantly lower than models. We investigate influence nova outbursts on formation (initial) evolution CVs. particular, we calculate stability mass transfer case all material accreted lost classical novae, part energy eject comes from a common-envelope like interaction...
Barium (Ba) dwarfs and CH subgiants are the less-evolved analogues of Ba giants. They F- to G-type main-sequence stars polluted with heavy elements by a binary companion when latter was on Asymptotic Giant Branch (AGB). This is now white dwarf that in most cases cannot be directly detected. We present large systematic study 60 objects classified as or subgiants. Combining radial-velocity measurements from HERMES SALT high-resolution spectra data CORAVEL CORALIE, we determine orbital...