A5042390990- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Nuclear Physics and Applications
- Nuclear physics research studies
- Nuclear reactor physics and engineering
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Radiation Detection and Scintillator Technologies
- Astrophysical Phenomena and Observations
- Radiation Therapy and Dosimetry
- Astronomical and nuclear sciences
- Pulsars and Gravitational Waves Research
- Particle physics theoretical and experimental studies
- Particle Detector Development and Performance
- Advanced Radiotherapy Techniques
- Neutrino Physics Research
- Nuclear Materials and Properties
- Astrophysics and Cosmic Phenomena
- Atomic and Molecular Physics
- Astronomical Observations and Instrumentation
- High-pressure geophysics and materials
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Dark Matter and Cosmic Phenomena
Istituto Nazionale di Fisica Nucleare, Sezione di Bari
2023-2024
Istituto Nazionale di Fisica Nucleare, Sezione di Perugia
2016-2024
Collurania Teramo Observatory
2015-2024
National Institute for Astrophysics
2009-2024
Istituto Nazionale di Fisica Nucleare
2017-2024
Istituto Nazionale di Fisica Nucleare, Sezione di Pavia
2024
Australian National University
2020
University of Manchester
2020
Istituto Nazionale di Fisica Nucleare, Sezione di Napoli
2000-2016
Boart Longyear (United States)
2009
The envelope of thermally pulsing AGB stars undergoing periodic third dredge-up episodes is enriched in both light and heavy elements, the ashes a complex internal nucleosynthesis involving p, alpha n captures over hundreds stable unstable isotopes. In this paper, new models low-mass (2 Msun), with metallicity ranging between Z=0.0138 (the solar one) Z=0.0001, are presented. Main features are: i) full nuclear network (from H to Bi) coupled stellar evolution code, ii) mass...
We present a new set of models for intermediate-mass asymptotic giant branch (AGB) stars (4.0, 5.0, and 6.0 M⊙) at different metallicities (−2.15 ≤ [Fe/H] +0.15). This integrates the existing low-mass AGB (1.3 M/M⊙ 3.0) already included in FRUITY database. describe physical chemical evolution computed from main sequence up to end phase. Due less efficient third dredge episodes, with large core masses show modest surface enhancements. effect is due fact that interpulse phases are short and,...
By using updated stellar low mass stars models, we can systematically investigate the nucleosynthesis processes occurring in AGB stars, when these objects experience recurrent thermal pulses and third dredge-up episodes. In this paper present database dedicated to of stars: FRUITY (FRANEC Repository Updated Isotopic Tables & Yields) database. An interactive web-based interface allows users freely download full (from H Bi) isotopic composition, as it changes after each episode yields models...
In this paper we analyze the effects induced by rotation on low mass Asymptotic Giant Branch stars. We compute two sets of models, M=2.0 Msun at [Fe/H]=0 and M=1.5 [Fe/H]=-1.7, respectively, adopting Main Sequence velocities in range 0 - 120 km/s. At high metallicity, find that Goldreich-Schubert-Fricke instability, active interface between convective envelope rapid rotating core, contaminates 13C-pocket (the major neutron source) with 14N poison), thus reducing flux available for synthesis...
The behaviour of carbon-oxygen white dwarfs (WDs) subject to direct helium accretion is extensively studied. We aim analyze the thermal response accreting WD mass deposition at different time scales. analysis has been performed for initial WDs masses and rates in range (0.60 - 1.02) Msun 1.e-9 1.e-5 Msun/yr, respectively. Thermal regimes parameters space M_{WD} dot{M}_{He}, leading formation red-giant-like structure, steady burning He, mild, strong dynamical flashes have identified...
Pulsating white dwarfs provide constraints to the evolution of progenitor stars. We revise He-burning stellar models, with particular attention core convection and its connection nuclear reactions powering energy generation chemical evolution. Theoretical results are compared available measurements for variable dwarf GD 358, which indicate a rather large abundance central oxygen (Metcalfe coworkers). show that attempt constrain relevant reaction rate by means composition is faced degree...
We present a comprehensive theoretical investigation of the evolutionary properties intermediate-mass stars. The sequences were computed from zero-age main sequence up to central He exhaustion and often phases that precede carbon ignition or reignition H-shell, which marks beginning thermal pulse phase. tracks constructed by adopting wide range stellar masses (3 ≤ M/M☉ 15) chemical compositions. In order account for current uncertainties on heavy elements enrichment ratio (ΔY/ΔZ), models at...
Extant chemical evolution models underestimate the Galactic production of Sr, Y and Zr as well Solar System abundances s-only isotopes with 90<A<130. To solve this problem, an additional (unknown) process has been invoked, so-called LEPP (Light Element Primary Process). In paper we investigate possible alternative solutions. Basing on Full Network Stellar evolutionary calculations, effects distribution induced by inclusion some commonly ignored physical processes (e.g. rotation) or variation...
Context. The production of neutrinos by plasma oscillations is the most important energy sink process operating in degenerate core low-mass red giant stars. This counterbalances release induced nuclear reactions and gravitational contraction, determines luminosity attained a star at moment He ignition. occurrence coincides with tip branch (RGB), whose extensively used as calibrated standard candle several cosmological studies. Aims. We aim to investigate possible activation additional...
Recent observations of heavy elements in Globular Clusters reveal intriguing deviations from the standard paradigm early galactic nucleosynthesis. If r-process contamination is a common feature halo stars, s-process enhancements are found few only. We show that combined pollution AGB stars with mass ranging between 3 to 6 M$_\odot$ may account for most features overabundance M4 and M22. In these s process mixture two different neutron-capture nucleosynthesis episodes. The first due...
Proton captures on Mg isotopes play an important role in the Mg–Al cycle active stellar H-burning regions. In particular, low-energy nuclear resonances 25Mg(p, γ)26Al reaction affect production of radioactive 26Algs as well resulting Mg/Al abundance ratio. Reliable estimations these quantities require precise measurements strengths resonances. Based a new experimental study performed at Laboratory for Underground Nuclear Astrophysics, we provide revised rates γ)26Algs and γ)26Alm reactions...
We analyze a set of published elemental abundances from sample CH stars which are based on high resolution spectral analysis ELODIE and SUBARU/HDS spectra. All the were derived local thermodynamic equilibrium usingmodel atmospheres, thus, they represent largest homogeneous abundance data available for up to date. For this reason, we can use constrain physics nucleosynthesis occurring in low mass AGB stars. have been polluted past an already extinct companion thus show s-process enriched...
We investigate the effect of rotation on evolution double-degenerate white dwarf systems, which are possible progenitors Type Ia supernovae. assume that prior to merging, two dwarfs rotate synchronously at orbital frequency and in merger process, lighter is transformed into a thick disk from more massive initially accretes very high rate (~10-5 M☉ yr-1). Because lifting rotation, accreting expands until gravitational acceleration centripetal required for binding surface become equal,...
We investigate the lifting effect of rotation on thermal evolution CO white dwarfs accreting CO-rich matter. find that induces cooling structure so delivered gravitational energy causes a greater expansion with respect to standard nonrotating case. The increase in surface radius produces decrease value critical angular velocity and, therefore, dwarf becomes gravitationally unbound (Roche instability). This occurrence is due an total momentum and depends critically amount specific deposited...
Silicon carbide (SiC) grains are a major dust component in carbon-rich AGB stars. The formation pathways of these are, however, not fully understood.\ We calculate ground states and energetically low-lying structures (SiC)$_n$, $n=1,16$ clusters by means simulated annealing (SA) Monte Carlo simulations seed subsequent quantum-mechanical calculations on the density functional level theory. derive infrared (IR) spectra compare IR signatures to observational laboratory data.\ According...
^{140}Ce(n,γ) is a key reaction for slow neutron-capture (s-process) nucleosynthesis due to being bottleneck in the flow. For this reason, it was measured with high accuracy (uncertainty ≈5%) at n_TOF facility, an unprecedented combination of purity sample and low neutron-sensitivity detectors. The Maxwellian averaged cross section up 40% higher than previously accepted values. Stellar model calculations indicate reduction around 20% s-process contribution Galactic cerium abundance smaller...
The recognition that the metallicity of Type Ia supernova (SNIa) progenitors might bias their use for cosmological applications has led to an increasing interest in its role shaping SNIa light curves. We explore sensitivity synthesized mass 56Ni, M(56Ni), progenitor starting from pre-main-sequence models with masses M0 = 2–7 M☉ and metallicities Z 10−5–0.10. interplay between convective mixing carbon burning during simmering phase eventually raises neutron excess, η, leads a smaller 56Ni...
In this paper we present the evolution of a low mass model (initial M=1.5 Msun) with very metal content (Z=5x10^{-5}, equivalent to [Fe/H]=-2.44). We find that, at beginning AGB phase, protons are ingested from envelope in underlying convective shell generated by first fully developed thermal pulse. This peculiar phase is followed deep third dredge up episode, which carries surface freshly synthesized 13C, 14N and 7Li. A standard TP-AGB evolution, then, follows. During proton ingestion high...
This work reports on accurate, high-resolution measurements of the $^{25}$Mg($n, \gamma$)$^{26}$Mg and tot$) cross sections in neutron energy range from thermal to about 300 keV, leading a significantly improved parametrization. The relevant resonances for $n+^{25}$Mg were characterized combined R-matrix analysis experimental data. resulted an unambiguous spin/parity assignment corresponding excited states $^{26}$Mg. With this information upper limits reaction rates $^{22}$Ne($\alpha,...
Abstract Recent improvements in stellar models for intermediate-mass stars and massive (MSs) are recalled, together with their expectations the synthesis of radioactive nuclei lifetimes τ ≲ 25 Myr, order to re-examine origins now extinct radioactivities that were alive solar nebula. The Galactic inheritance broadly explains most them, especially if r -process produced by neutron star merging, according recent models. Instead, 26 Al, 41 Ca, 135 Cs, possibly 60 Fe require nucleosynthetic...
Context. Material processed by the CNO cycle in stellar interiors is enriched 17O. When mixing processes from surface reach these layers, as occurs when stars become red giants and undergo first dredge up, abundance of 17O increases. Such an occurrence explains drop 16O/17O observed RGB with mass larger than 1.5 M_\solar. As a consequence, interstellar medium continuously polluted wind evolved . Aims. Recently, Laboratory for Underground Nuclear Astrophysics (LUNA) collaboration released...
Abstract We revise the theoretical initial mass–final luminosity relation for progenitors of Type IIP and IIL supernovae. The effects major uncertainties, such as those due to treatment convection, semiconvection, rotation, mass loss, nuclear reaction rates, neutrinos production are discussed in some detail. transfer between components close-binary systems also considered. By comparing predictions a sample II supernovae which pre-explosive available, we conclude that stellar rotation may...
ABSTRACT Novae are the observational manifestations of thermonuclear runaways on surface accreting white dwarfs (WDs). Although novae an ubiquitous phenomenon, their properties at low metallicity not well understood. Using publicly-available stellar evolution code Modules for Experiments in Stellar Astrophysics (mesa), we model carbon–oxygen WDs and consider models that accrete matter with Z = 0.02 or 10−4. We both without mixing enriched by CO-elements assuming occurs process accretion...
The vast majority (>=90%) of presolar SiC grains identified in primitive meteorites are relics ancient asymptotic giant branch (AGB) stars, whose ejecta were incorporated into the Solar System during its formation. Detailed characterization these stardust has revealed precious information on mixing processes AGB interiors great detail. However, mass and metallicity distribution their parent stars still remains ambiguous, although such is crucial to investigating slow neutron capture process,...
Abstract In accreting white dwarfs (WDs) approaching the Chandrasekhar limit, hydrostatic carbon burning precedes dynamical breakout. During this simmering phase, e -captures are energetically favored in central region of star, while β -decay more outside, and two zones connected by a growing convective instability. We analyze interplay between weak interactions convection, so-called URCA process, during phase Type Ia supernovae (SNe Ia) progenitors its effects on physical chemical...