A5009678186- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Nuclear physics research studies
- Astrophysics and Star Formation Studies
- Nuclear Physics and Applications
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Nuclear reactor physics and engineering
- Adaptive optics and wavefront sensing
- Calibration and Measurement Techniques
- Astronomical and nuclear sciences
- Planetary Science and Exploration
- Solar and Space Plasma Dynamics
- Radiation Detection and Scintillator Technologies
- Scientific Research and Discoveries
- Infrared Target Detection Methodologies
- Geomagnetism and Paleomagnetism Studies
- High-pressure geophysics and materials
- Particle physics theoretical and experimental studies
- History and Developments in Astronomy
- Atmospheric Ozone and Climate
- Neutrino Physics Research
- Radiation Therapy and Dosimetry
- Pulsars and Gravitational Waves Research
University of Perugia
2015-2024
Istituto Nazionale di Fisica Nucleare, Sezione di Perugia
2015-2024
Istituto Nazionale di Fisica Nucleare, Sezione di Bari
2018-2024
Universidad Nacional de Córdoba
2024
Universidad Empresarial Siglo 21
2024
Ospedale Amedeo di Savoia
2024
Istituto Nazionale di Fisica Nucleare
2022-2023
Australian National University
2020
Arcetri Astrophysical Observatory
2013
Universidad de Granada
2011
▪ Abstract We present a review of nucleosynthesis in AGB stars outlining the development theoretical models and their relationship to observations. focus on new high resolution codes with improved opacities, which recently succeeded accounting for third dredge-up. This opens possibility understanding low luminosity C (enriched s-elements) as normal outcome evolution, characterized by production 12 neutron-rich nuclei He intershell mass loss from strong stellar winds. Neutron captures are...
The recently improved information on the stellar (n,gamma) cross sections of neutron-magic nuclei at N = 82, and in particular 142Nd, turned out to represent a sensitive test for models s-process nucleosynthesis. While these data were found be incompatible with classical approach based an exponential distribution neutron exposures, they provide significantly better agreement between solar abundance s predictions low mass AGB stars. Particular attention is paid consistent description...
We present a new analysis of neutron capture occurring in low-mass asymptotic giant branch (AGB) stars suffering recurrent thermal pulses. use dedicated evolutionary models for initial mass the range 1 to 3 M☉ and metallicity from solar half solar. Mass loss is taken into account with Reimers parameterization. The third dredge-up mechanism self-consistently found occur after limited number pulses, mixing envelope freshly synthesized 12C s-processed material He intershell. During temperature...
We present the results of s-process nucleosynthesis calculations for asymptotic giant branch (AGB) stars different metallicities and initial stellar masses (1.5 3 M☉), we comparisons them with observational constraints from high-resolution spectroscopy evolved over a wide metallicity range. The computations were based on previously published evolutionary models that account third dredge-up phenomenon occurring late AGB. Neutron production is driven by 13C(α, n)16O reaction during interpulse...
view Abstract Citations (294) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Radiative 13C Burning in Asymptotic Giant Branch Stars and s-Processing Straniero, O. ; Gallino, R. Busso, M. Chiefei, A. Raiteri, C. Limongi, Salaris, We present new evolutionary calculations for a 3 solar mass of Population I starting from zero-age main sequence followed up to the 25th thermal pulse asymptotic giant branch. The third dredge-up is found occur...
Abundances of 244Pu,235U,238U, and 232Th in the early solar system are about those expected for uniform production over most galactic history. The inferred abundance 182Hf is also compatible with this model. We here associate same r-process SN sources that produce actinides (SNACS). This requires nucleosynthesis SNACS took place rather uniformly age galaxy until ~107 yr prior to formation. low 107Pd 129I indicates cannot these nuclei at high yields from standard models. propose there...
Certain bis(heteroaryl)piperazines (BHAPs) are potent inhibitors of the human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) at concentrations lower by 2-4 orders magnitude than that which inhibits normal cellular DNA polymerase activity. Combination a BHAP with nucleoside analog HIV-1 RT suggested together these compounds inhibited synergistically. In three lymphocytic cell systems using several laboratory and clinical isolates, BHAPs blocked replication potencies nearly...
We examine the effects of cool bottom processing (CBP) on isotopic ratios 18O/16O, 17O/16O, 14N/15N, 26Al/27Al, C/O, and N/O in convective envelope during thermally pulsing asymptotic giant branch (TP-AGB) phase evolution a 1.5 M☉ initial mass star solar composition. use parametric model that treats extra mixing by introducing flow between underlying radiative zone. The parameters this are circulation rate () maximum temperature (TP) experienced circulating material. nuclear reactions...
We follow the chemical evolution of Galaxy for elements from Ba to Eu, using an evolutionary model suitable reproduce a large set Galactic (local and non local) extragalactic constraints. Input stellar yields neutron-rich nuclei have been separated into their s-process r-process components. The production in thermally pulsing asymptotic giant branch stars low mass proceeds combined operation two neutron sources: dominant reaction 13C(alpha,n)16O, which releases neutrons radiative conditions...
We present abundances for 22 chemical elements in 10 red giant members of the massive Galactic globular cluster ω Centauri. The spectra are relatively high spectral resolution and signal-to-noise. Using these plus published literature values, abundance trends defined as a function standard metallicity indicator iron. lowest stars Cen have [Fe/H] ∼ -1.8, initial distribution is established at this metallicity. span range -1.8 to -0.8. At metallicity, heavy-element found be well characterized...
New models of thermally pulsing asymptotic giant branch (TP-AGB) stars low mass and solar chemical composition are presented, namely, 1 ≤ M/M☉ 3, Z = 0.02, Y 0.28. The influence various parameters (such as the initial core mass, envelope mass-loss rate, opacity, mixing length) on properties is discussed in detail. Our main findings following:
Rigorous methods for the post-HF (HF—Hartree–Fock) determination of correlation corrections crystalline solids are currently being developed following different strategies. The CRYSTAL program in Torino and Daresbury provides accurate HF solutions periodic systems a basis set Gaussian type functions; insulators, occupied manifold can be represented as an antisymmetrized product well localized Wannier functions. This makes possible extension to nonconducting crystals local linear scaling On...
view Abstract Citations (180) References (54) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Weak s-Component and Nucleosynthesis in Massive Stars Raiteri, C. M. ; Gallino, R. Busso, Neuberger, D. Kaeppeler, F. difficulties of the phenomenological analysis weak s-component need for a comparison with astrophysical picture are discussed. New results s-process calculations massive stars during both core He shell C burning presented. They obtained after...
view Abstract Citations (181) References (57) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS S-Process Nucleosynthesis: Classical Approach and Asymptotic Giant Branch Models for Low-Mass Stars Kaeppeler, F. ; Gallino, R. Busso, M. Picchio, G. Raiteri, C. A critical comparison is made between the results of s-process nucleosynthesis obtained with phenomenological classical approach a stellar model helium shell burning in low-mass stars. For first time, close...
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...
We present new spectroscopic observations for a sample of C(N)-type red giants. These objects belong to the class Asymptotic Giant Branch stars, experiencing thermal instabilities in He-burning shell (thermal pulses). Mixing episodes called third dredge-up enrich photosphere with newly synthesized C12 He-rich zone, and this is source high observed ratio between carbon oxygen (C/O > 1 by number). Our abundance estimates confirm that, agreement general understanding late evolutionary stages...
We present the first detailed and homogeneous analysis of s-element content in Galactic carbon stars N type. Abundances Sr, Y, Zr (low-mass s-elements, or ls), Ba, La, Nd, Sm, Ce (high-mass hs) are derived using spectral synthesis technique from high-resolution spectra. The analyzed nearly solar metallicity show moderate enhancements, similar to those found S stars, but smaller than only previous study (Utsumi 1985), also supergiant post-asymptotic giant branch (post-AGB) stars. This is...
Bisheteroarylpiperazines are potent inhibitors of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT). We describe a novel bisheteroarylpiperazine, U-90152 [1-(5-methanesulfonamido-1H-indol-2-yl-carbonyl)-4-[3-(1-methyl eth yl-amino)pyridinyl]piperazine], which inhibited recombinant HIV-1 RT at 50% inhibitory concentration (IC50) 0.26 microM (compared with IC50s > 440 for DNA polymerases alpha and delta). blocked the replication in peripheral blood lymphocytes 25...
It is known that there must be some weak form of transport (called cool bottom processing, or CBP) acting in low-mass red giant branch (RGB) and asymptotic (AGB) stars, adding nuclei, newly produced near the hydrogen-burning shell, to convective envelope. We assume this extra mixing originates a stellar dynamo operated by differential rotation below envelope, maintaining toroidal magnetic fields shell. use phenomenological approach buoyancy flux tubes, assuming they induce matter circulation...
view Abstract Citations (124) References (40) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS S-Process Nucleosynthesis in Massive Stars and the Weak Component. II. Carbon Burning Galactic Enrichment Raiteri, C. M. ; Busso, Gallino, R. Picchio, G. The s-process that occurs shell carbon-burning phase of a typical massive star 25 solar masses is examined. It shown neutron captures during C-burning can significantly change s-abundances. composition s-processed...