A5017645314- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Nuclear physics research studies
- Nuclear Physics and Applications
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Nuclear reactor physics and engineering
- Gamma-ray bursts and supernovae
- Radiation Detection and Scintillator Technologies
- Astronomical and nuclear sciences
- Pulsars and Gravitational Waves Research
- High-pressure geophysics and materials
- Particle physics theoretical and experimental studies
- Astronomical Observations and Instrumentation
- Particle Detector Development and Performance
- Radiation Therapy and Dosimetry
- Scientific Research and Discoveries
- Astrophysical Phenomena and Observations
- Neutrino Physics Research
- Particle accelerators and beam dynamics
- Atomic and Subatomic Physics Research
- Nuclear Materials and Properties
- Quantum Chromodynamics and Particle Interactions
- Geomagnetism and Paleomagnetism Studies
- Planetary Science and Exploration
Istituto Nazionale di Fisica Nucleare, Sezione di Perugia
2011-2024
Collurania Teramo Observatory
2015-2024
National Institute for Astrophysics
2010-2024
Istituto Nazionale di Fisica Nucleare, Sezione di Bari
2018-2024
Istituto Nazionale di Fisica Nucleare
2017-2024
University of Pavia
2024
Istituto Nazionale di Fisica Nucleare, Sezione di Pavia
2024
Keele University
2021
Australian National University
2020
Florence (Netherlands)
2019
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,...
We present a comprehensive study of the abundance evolution elements from H to U in Milky Way halo and local disk. use consistent chemical model, metallicity dependent isotopic yields low intermediate mass stars massive which include, for first time, combined effect metallicity, loss rotation large grid stellar masses all stages evolution. The are weighted by function rotational velocities, constrained observations as obtain primary-like $^{14}$N behavior at avoid overproduction s-elements...
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...
High-resolution spectroscopic observations of 100 metal-poor carbon and s-rich stars (CEMP-s) collected from the literature are compared with theoretical nucleosynthesis models asymptotic giant branch (AGB) presented in Paper I (MAGBini= 1.3, 1.4, 1.5, 2 M⊙, − 3.6 ≲ [ Fe/H ] ≲− 1.5). The s-process enhancement detected these objects is associated binary systems: more massive companion evolved faster through thermally pulsing AGB phase (TP-AGB), synthesizing s-elements inner He intershell,...
We present new optical and near infrared (NIR) photometry spectroscopy of the type IIP supernova, SN 2004et. In combination with already published data, this provides one most complete studies NIR data for any from just after explosion to +500 days. The contribution flux bolometric light curve is estimated increase 15% at around 50% end plateau then declines 40% 300 2004et luminous SNe which has been well studied, a luminosity log L = 42.3 erg/s, it 2 times brighter than 1999em. provide...
We present computations of nucleosynthesis in low-mass (LM) red giant branch (RGB) and asymptotic (AGB) stars Population I experiencing extended mixing. adopt the updated version FRANEC evolutionary model, a new post-process code for non-convective mixing most recent revisions solar abundances. In this framework, we discuss effects improvements relevant reaction rates proton captures on intermediate-mass (IM) nuclei (from carbon to aluminum). For each nucleus, briefly choices their...
A large sample of carbon enhanced metal-poor stars enriched in s-process elements (CEMP-s) have been observed the Galactic halo. These low mass (M ~ 0.9 Msun) are located on main-sequence or red giant phase, and do not undergo third dredge-up (TDU) episodes. The enhancement is most plausibly due to accretion a binary system from more massive companion when asymptotic branch (AGB) phase (now white dwarf). In order interpret spectroscopic observations, updated AGB models needed follow detail...
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...
We provide an individual analysis of 94 carbon enhanced metal-poor stars showing s-process enrichment (CEMP-s) collected from the literature. The enhancement observed in these is ascribed to mass transfer by stellar winds a binary system more massive companion evolving faster toward asymptotic giant branch (AGB) phase. theoretical AGB nucleosynthesis models have been presented Paper I. Several CEMP-s show both s and r-process elements (CEMP-s/r). In order explain peculiar abundances CEMP-s/r...
The energy-dependent cross section of the ^{7}Be(n,α)^{4}He reaction, interest for so-called cosmological lithium problem in big bang nucleosynthesis, has been measured first time from 10 meV to keV neutron energy. challenges posed by short half-life ^{7}Be and low reaction have overcome at n_TOF thanks an unprecedented combination extremely high luminosity good resolution beam new experimental area (EAR2) facility CERN, availability a sufficient amount chemically pure ^{7}Be, specifically...
The decomposition of the Solar system abundances heavy isotopes into their s- and r- components plays a key role in our understanding corresponding nuclear processes physics evolution astrophysical sites. We present new method for determining abundances, fully consistent with current stellar nucleosynthesis galactic chemical evolution. is based on study solar neighborhood state-of-the-art 1-zone model, using recent yields low intermediate mass stars as well massive rotating stars. compare...
We study the production of very light elements ($Z < 20$) in dynamical and spiral-wave wind ejecta binary neutron star mergers by combining detailed nucleosynthesis calculations with outcome numerical relativity merger simulations. All our models are targeted to GW170817 include neutrino radiation. explore different finite-temperature, composition dependent nuclear equations state mass ratios, find that hydrogen helium most abundant elements. For both elements, decay free neutrons is driving...
This paper provides a detailed analysis of the main component slow neutron capture process (the s-process), which accounts for solar abundances half nuclei with 90 <~ A 208. We examine impact uncertainties two sources operating in low-mass asymptotic giant branch (AGB) stars: 13C(alpha, n)16O reaction, releases neutrons radiatively during interpulse periods (kT ~ 8 keV), and 22Ne(alpha, n)25Mg partially activated convective thermal pulses (TPs). focus our attention on branching points that...
We present barium, carbon, and silicon isotopic compositions of 38 acid-cleaned presolar SiC grains from Murchison. Comparison with previous data shows that acid washing is highly effective in removing barium contamination. Strong depletions δ(138Ba/136Ba) values are found, down to −400‰, which can only be modeled a flatter 13C profile within the pocket than normally used. The dependence predictions on distribution asymptotic giant branch (AGB) models allows us probe mass AGB stars. In...
We report on the measurement of ^{7}Be(n,p)^{7}Li cross section from thermal to approximately 325 keV neutron energy, performed in high-flux experimental area (EAR2) n_TOF facility at CERN. This reaction plays a key role lithium yield big bang nucleosynthesis (BBN) for standard cosmology. The only two previous time-of-flight measurements this did not cover energy window interest BBN, and they showed large discrepancy between each other. was with Si telescope high-purity sample produced by...
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...
We present strontium, barium, carbon, and silicon isotopic compositions of 61 acid-cleaned presolar SiC grains from Murchison. Comparison with previous data shows that acid washing is highly effective in removing both strontium barium contamination. For the first time, by using correlated 88Sr/86Sr 138Ba/136Ba ratios mainstream grains, we are able to resolve effect 13C concentration 13C-pocket mass on s-process nucleosynthesis, which points toward existence large pockets low concentrations...
Isotope ratios can be measured in presolar SiC grains from ancient Asymptotic Giant Branch (AGB) stars at permil-level (0.1\%) precision. Such precise grain data permit derivation of more stringent constraints and calibrations on mixing efficiency AGB models than traditional spectroscopic observations. In this paper we compare heavy-element isotope to a new series FRUITY that include the effects triggered by magnetic fields. Based 2D 3D simulations available literature, propose formulation,...
One of the main neutron sources for astrophysical s process is reaction ^{13}C(α,n)^{16}O, taking place in thermally pulsing asymptotic giant branch stars at temperatures around 90 MK. To model nucleosynthesis during this cross section needs to be known 150-230 keV energy window (Gamow peak). At these sub-Coulomb energies, direct measurements are severely affected by low event rate, making us rely on input from indirect methods and extrapolations higher-energy data. This leads an uncertainty...
Abstract We present post-process neutron-capture computations for Asymptotic Giant Branch (AGB) stars of 1.5–3 M ⊙ and metallicities −1.3 ≤ [Fe/H] 0.1. The reference stellar models are computed with the FRANEC code, using Schwarzschild's criterion convection; our motivations this choice outlined. assume that MHD processes induce penetration protons below convective boundary, when Third Dredge Up occurs. There, 13 C n -source can subsequently operate, merging its effects those 22 Ne( α , n)...
Using a semi-analytical model of the evolution Milky Way, we show how secular can create distinct overdensities in phase space various properties (e.g. age vs metallicity or abundance ratios age) corresponding to thin and thick discs. In particular, key Solar vicinity be obtained by evolution, with no need for external special events, like galaxy mergers paucity star formation. This concerns long established double-branch behaviour [alpha/Fe] recently found non-monotonic stellar gradient,...
An analysis of the fluorine abundance in Galactic asymptotic giant branch (AGB) carbon stars (24 N-type, 5 SC-type, and J-type) is presented. This study uses state-of-the-art carbon-rich atmosphere models improved atomic molecular line lists 2.3 μm region. Significantly lower F abundances are obtained comparison to previous studies literature. difference mainly due blends. In case differences model atmospheres also relevant. The new enhancements now agreement with most recent theoretical...
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...