scholarly journals Nucleosynthesis in neutrino-driven, aspherical Population III supernovae

2011 ◽  
Vol 7 (S279) ◽  
pp. 237-240
Author(s):  
Shin-ichiro Fujimoto ◽  
Masa-aki Hashimoto ◽  
Masaomi Ono ◽  
Kei Kotake
Keyword(s):  
Nuclear Reaction ◽  
Atomic Number ◽  
Reaction Network ◽  
Explosion Energy ◽  
Two Dimensional ◽  
Post Processing ◽  
Hydrodynamic Simulations ◽  
Artificial Mixing ◽  
Spherical Models ◽  
Accretion Shock

AbstractWe investigate explosive nucleosynthesis during neutrino-driven, aspherical supernova (SN) explosion aided by standing accretion shock instability (SASI), based on two-dimensional hydrodynamic simulations of the explosion of 11, 15, 20, 25, 30 and 40M⊙ stars with zero metallicity. The magnitude and asymmetry of the explosion energy are estimated with simulations, for a given set of neutrino luminosities and temperatures, not as in the previous study in which the explosion is manually and spherically initiated by means of a thermal bomb or a piston and also some artificial mixing procedures are applied for the estimate of abundances of the SN ejecta.By post-processing calculations with a large nuclear reaction network, we have evaluated abundances and masses of ejecta from the aspherical SNe. We find that matter mixing induced via SASI is important for the abundant production of nuclei with atomic number ≥ 21, in particular Sc, which is underproduced in the spherical models without artificial mixing. We also find that the IMF-averaged abundances are similar to those observed in extremely metal poor stars. However, observed [K/Fe] cannot be reproduced with our aspherical SN models.

scholarly journals Two‐Dimensional Multiangle, Multigroup Neutrino Radiation‐Hydrodynamic Simulations of Postbounce Supernova Cores

2008 ◽  
Vol 685 (2) ◽  
pp. 1069-1088 ◽  
Author(s):  
Christian D. Ott ◽  
Adam Burrows ◽  
Luc Dessart ◽  
Eli Livne
Keyword(s):  
Two Dimensional ◽  
Hydrodynamic Simulations ◽  
Neutrino Radiation

scholarly journals Global predictions for astrophysics applications

2020 ◽  
Vol 13 ◽  
pp. 18
Author(s):  
P. Demetriou
Keyword(s):  
Nuclear Reaction ◽  
Cross Sections ◽  
Nuclear Reactions ◽  
Nuclear Astrophysics ◽  
Reaction Network ◽  
Reaction Rates ◽  
Reaction Cross ◽  
Hartree Fock ◽  
Microscopic Models ◽  
The Stability

Nuclear reaction rates play a crucial role in nuclear astrophysics. In the last decades there has been an enormous effort to measure reaction cross sections and extensive experimental databases have been compiled as a result. In spite of these efforts, most nuclear reaction network calculations still have to rely on theoretical predic- tions of experimentally unknown rates. In particular, in astrophysics applications such as the s-, r- and p-process nucleosynthesis involving a large number of nuclei and nuclear reactions (thousands). Moreover, most of the ingredients of the cal- culations of reaction rates have to be extrapolated to energy and/or mass regions that cannot be explored experimentally. For this reason it is important to develop global microscopic or semi-microscopic models of nuclear properties that give an accurate description of existing data and are reliable for predictions far away from the stability line. The need for more microscopic input parameters has led to new devel- opments within the Hartree-Fock-Bogoliubov method, some of which are presented in this paper.

scholarly journals A numerical study of the interaction between two ejecta in the interplanetary medium: one- and two-dimensional hydrodynamic simulations

2004 ◽  
Vol 22 (10) ◽  
pp. 3741-3749 ◽  
Author(s):  
A. Gonzalez-Esparza ◽  
A. Santillán ◽  
J. Ferrer
Keyword(s):  
Hydrodynamic Model ◽  
Physical Mechanism ◽  
Interplanetary Medium ◽  
Numerical Study ◽  
Two Dimensions ◽  
Magnetic Clouds ◽  
The Sun ◽  
Two Dimensional ◽  
Hydrodynamic Simulations

Abstract. We studied the heliospheric evolution in one and two dimensions of the interaction between two ejecta-like disturbances beyond the critical point: a faster ejecta 2 overtaking a previously launched slower ejecta 1. The study is based on a hydrodynamic model using the ZEUS-3-D code. This model can be applied to those cases where the interaction occurs far away from the Sun and there is no merging (magnetic reconnection) between the two ejecta. The simulation shows that when the faster ejecta 2 overtakes ejecta 1 there is an interchange of momentum between the two ejecta, where the leading ejecta 1 accelerates and the tracking ejecta 2 decelerates. Both ejecta tend to arrive at 1AU having similar speeds, but with the front of ejecta 1 propagating faster than the front of ejecta 2. The momentum is transferred from ejecta 2 to ejecta 1 when the shock initially driven by ejecta 2 passes through ejecta 1. Eventually the two shock waves driven by the two ejecta merge together into a single stronger shock. The 2-D simulation shows that the evolution of the interaction can be very complex and there are very different signatures of the same event at different viewing angles; however, the transferring of momentum between the two ejecta follows the same physical mechanism described above. These results are in qualitative agreement with in-situ plasma observations of "multiple magnetic clouds" detected at 1AU.

General principles of echocardiography

2016 ◽  
Author(s):  
Madalina Garbi ◽  
Jan D’hooge ◽  
Evgeny Shkolnik
Keyword(s):  
Blood Flow ◽  
Image Interpretation ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Post Processing ◽  
Ultrasound Waves ◽  
Advantages And Disadvantages ◽  
Biologic Effects ◽  
Flow Through ◽  
And Function

Echocardiography uses ultrasound waves to generate images of cardiovascular structures and to display information regarding the blood flow through these structures. Knowledge of basic ultrasound principles and current technology is essential for image interpretation and for optimal use of equipment during image acquisition and post-processing. This chapter starts by presenting the physics of ultrasound and the construction and function of instruments. Image formation, optimization, display, presentation, storage, and communication are explained. Advantages and disadvantages of available imaging modes (M-mode, two-dimensional, and three-dimensional) are detailed and imaging artefacts are illustrated. The potential biologic effects of ultrasound and the need for quality assurance are discussed.

scholarly journals The QSE‐Reduced Nuclear Reaction Network for Silicon Burning

2007 ◽  
Vol 667 (1) ◽  
pp. 476-488 ◽  
Author(s):  
W. Raphael Hix ◽  
Suzanne T. Parete‐Koon ◽  
Christian Freiburghaus ◽  
Friedrich‐Karl Thielemann
Keyword(s):  
Nuclear Reaction ◽  
Reaction Network

The Effects of New Nuclear Reaction Rates and Opacities on Hydrodynamic Simulations of the Nova Outburst

2000 ◽  
Vol 127 (2) ◽  
pp. 485-495 ◽  
Author(s):  
S. Starrfield ◽  
W. M. Sparks ◽  
J. W. Truran ◽  
M. C. Wiescher
Keyword(s):  
Nuclear Reaction ◽  
Reaction Rates ◽  
Hydrodynamic Simulations ◽  
Nova Outburst

scholarly journals Revisiting nucleosynthesis in globular clusters

2017 ◽  
Vol 608 ◽  
pp. A28 ◽  
Author(s):  
N. Prantzos ◽  
C. Charbonnel ◽  
C. Iliadis
Keyword(s):  
Nuclear Reaction ◽  
Constant Temperature ◽  
Globular Clusters ◽  
Chemical Properties ◽  
Reaction Network ◽  
Stellar Populations ◽  
Reaction Rates ◽  
Temperature Range

Context. Motivated by recent reports concerning the observation of limited enrichment in He but excess K in stars of globular clusters, we revisit the H-burning conditions that lead to the chemical properties of multiple stellar populations in these systems. Aims. In particular, we are interested in correlations of He and K with other elements, such as O, Na, Al, Mg and Si, reported in stars of NGC 2808. Methods. We performed calculations of nucleosynthesis at constant temperature and density, exploring the temperature range of 25 to 200 × 106 K (25 to 200 MK), using a detailed nuclear reaction network and the most up-to-date nuclear reaction rates. Results. We find that Mg is the most sensitive “thermometer” of hydrostatic H-burning conditions, pointing to a temperature range of 70–80 MK for NGC 2808, while He is a lesser – but not negligible – constraint. Potassium can be produced at the levels reported for NGC 2808 at temperatures >180 MK and Si at T > 80 MK. However, in the former temperature range Al and Na are totally destroyed and no correlation can be obtained, in contrast to the reported observations. None of the putative polluter sources proposed so far seem to satisfy the ensemble of nucleosynthesis constraints.

Sign in / Sign up

Export Citation Format

Share Document