scholarly journals Co-Production of Light p-, s- and r-Process Isotopes in the High-Entropy Wind of Type II Supernovae

2009 ◽  
Vol 26 (3) ◽  
pp. 194-202 ◽  
Author(s):  
K. Farouqi ◽  
K.-L. Kratz ◽  
B. Pfeiffer
Keyword(s):  
Stable Isotopes ◽  
Charged Particle ◽  
Solar System ◽  
Large Scale ◽  
Type Ii ◽  
Isotopic Abundance ◽  
Isotopic Chain ◽  
High Entropy ◽  
R Process ◽  
Particle Process

AbstractWe have performed large-scale nucleosynthesis calculations within the high-entropy-wind (HEW) scenario of Type II supernovae. The primary aim was to constrain the conditions for the production of the classical ‘p-only’ isotopes of the light trans-Fe elements. We find, however, that for electron fractions in the range 0.458 ≤ Ye ≤ 0.478, sizeable abundances of p-, s- and r-process nuclei between 64Zn and 98Ru are coproduced in the HEW at low entropies (S ≤ 100) by a primary charged-particle process after an α-rich freezeout. With the above Ye–S correlation, most of the predicted isotopic abundance ratios within a given element, e.g. 64Zn(p)/70Zn(r) or 92Mo(p)/94Mo(p), as well as of neighboring elements, e.g. 70Ge(s + p)/74Se(p) or 74Se(p)/78Kr(p) agree with the observed Solar-System ratios. Taking the Mo isotopic chain as a particularly challenging example, we show that our HEW model can account for the production of all 7 stable isotopes, from ‘p-only’ 92Mo, via ‘s-only’ 96Mo up to ‘r-only’ 100Mo. Furthermore, our model is able to reproduce the isotopic composition of Mo in presolar SiC X-grains.

scholarly journals Nucleosynthesis of light trans-Fe isotopes in ccSNe: Implications from presolar SiC-X grains

2020 ◽  
Vol 227 ◽  
pp. 01009
Author(s):  
Waheed Akram ◽  
Khalil Farouqi ◽  
Oliver Hallmann ◽  
Karl-Ludwig Kratz
Keyword(s):  
Charged Particle ◽  
Massive Stars ◽  
Parameter Study ◽  
Type Ii ◽  
High Entropy ◽  
Abundance Estimates ◽  
Fe Isotopes ◽  
Type Ia ◽  
R Process ◽  
Low Entropy

This contribution presents an extension of our r-process parameter study within the high-entropy-wind (HEW) scenario of corecollapse supernovae (ccSNe). One of the primary aims of this study was to obtain indications for the production of classical p-, s- and r-isotopes of the light trans-Fe elements in the Solar System (S.S.). Here, we focus on the nucleosynthesis origin of the anomalous isotopic compositions of Zr, Mo and Ru in presolar SiC X-grains (SNe grains). In contrast to the interpretation of other groups, we show that these grains do not represent the signatures of a ‘clean’ stellar scenario, but rather, are mixtures of an exotic nucleosynthesis component and S.S. material. We further confirm the results of our earlier studies whereby sizeable amounts of all stable p-, s- and r-isotopes of Zr, Mo and Ru can be co-produced by moderately neutron-rich ejecta of the low-entropy, charged-particle scenario of ccSNe (type II). The synthesis of these isotopes through a ‘primary’ production mode provides further means to revise the abundance estimates of the light trans-Fe elements from so far favoured ‘secondary’ scenarios like Type Ia SNe or neutron-bursts in exploding massive stars.

Astrophysical conditions for an r-process in the high-entropy wind scenario of type II supernovae

2005 ◽  
Vol 758 ◽  
pp. 631-634 ◽  
Author(s):  
K. Farouqi ◽  
C. Freiburghaus ◽  
K.-L. Kratz ◽  
B. Pfeiffer ◽  
T. Rauscher ◽  
...  
Keyword(s):  
Type Ii ◽  
High Entropy ◽  
R Process

scholarly journals R-Process nucleosynthesis in high entropy environment in explosion of supernova type II and neutron star formation

2012 ◽  
Vol 8 (S291) ◽  
pp. 352-352
Author(s):  
Rulee Baruah ◽  
Kalpana Duorah ◽  
H. L. Duorah
Keyword(s):  
Neutron Star ◽  
Supernova Explosion ◽  
Neutron Number ◽  
Iron Core ◽  
Type Ii ◽  
Fusion Reactions ◽  
Capture Process ◽  
High Entropy ◽  
Wave Forms ◽  
R Process

AbstractIt is generally acknowledged that Type II supernovae result from the collapse of iron core of a massive star which, at least in some cases, produces a neutron star. At this stage, the neutrinos are produced by neutronization which speeds up as collapse continues. During collapse an outward bound shock wave forms in the matter falling onto the nearly stationary core. The conditions behind the shock at 100 to 200 km are suitable for neutrino heating. This neutrino heating blows a hot bubble above the protoneutron star and is the most important source of energy for Supernova explosion. At this stage, we try to attain the r-process (rapid neutron capture process) path responsible for the production of heavy elements beyond iron, which are otherwise not possible to be formed by fusion reactions. The most interesting evolution occurs as temperature falls from 1010 K to 109 K. At these high temperature conditions, the critical fluids after fusion reactions are forbidden and transform into the respective atoms by r-process path which on beta decaying produce the ultimate elements of the periodic chart.Another astrophysical parameter needed for our analysis is neutron number density which we take to be greater than 1020 cm−3. With these, at different entropy environments, we assign the neutron binding energy that represents the r-process path in the chart of nuclides. Along the path, the experimental data of observed elements matches our calculated one. We find that an entropy of ~300 with Ye ≃ 0.45 can lead to a successful r-process. It produced heavy neutron-rich nuclei with A ≃ 80 – 240. Later ejecta are neutron-rich (Ye ≤ 0.5) and leaves behind a compact neutron star.

scholarly journals The frequency of stellar X-ray flares from a large-scale XMM-Newton sample

2015 ◽  
Vol 11 (S320) ◽  
pp. 134-137
Author(s):  
John P. Pye ◽  
Simon R. Rosen
Keyword(s):  
Solar System ◽  
Solar Flare ◽  
Space Weather ◽  
White Light ◽  
Large Scale ◽  
The Sun ◽  
X Ray ◽  
Cool Star ◽  
Exoplanetary Systems ◽  
Solar Type

AbstractWe present estimates of cool-star X-ray flare rates determined from the XMM-Tycho survey (Pyeet al. 2015, A&A, 581, A28), and compare them with previously published values for the Sun and for other stellar EUV and white-light samples. We demonstrate the importance of applying appropriate corrections, especially in regard to the total, effective size of the stellar sample. Our results are broadly consistent with rates reported in the literature for Kepler white-light flares from solar-type stars, and with extrapolations of solar flare rates, indicating the potential of stellar X-ray flare observations to address issues such as ‘space weather’ in exoplanetary systems and our own solar system.

Chemical affinity assisted H2 isotope separation using Ca-rich onion-peel-derived nanoporous carbon composite

2021 ◽  
Author(s):  
Raeesh Muhammad ◽  
Suhwan Kim ◽  
Jaewoo Park ◽  
Minji Jung ◽  
Myeongeun Lee ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Large Scale ◽  
Isotope Separation ◽  
Carbon Composite ◽  
Nanoporous Carbon ◽  
Chemical Affinity ◽  
Scientific Applications ◽  
Onion Peel

Stable isotopes of hydrogen are a prerequisite for many industrial and scientific applications and require their ready supply at a large scale. Herein, we explore the chemical affinity-assisted separation of...

scholarly journals Stratigraphy, stable isotopes and salinity in multi-year sea ice from the rift area, south George VI Ice Shelf, Antarctic Peninsula

1991 ◽  
Vol 37 (127) ◽  
pp. 357-367
Author(s):  
J.-L. Tison ◽  
E. M. Morris ◽  
R. Souchez ◽  
J. Jouzel
Keyword(s):  
Stable Isotopes ◽  
Sea Ice ◽  
Fresh Water ◽  
Large Scale ◽  
Sea Water ◽  
Ice Core ◽  
Ice Shelf ◽  
The Core ◽  
Brackish Ice ◽  
Ice Production

AbstractResults from a detailed profile in a 5.54 m multi-year sea-ice core from the rift area in the southern part of George VI Ice Shelf are presented. Stratigraphy, stable isotopes and Na content are used to investigate the growth processes of the ice cover and to relate them to melting processes at the bottom of the ice shelf.The thickest multi-year sea ice in the sampling area appears to be second-year sea ice that has survived one melt season. Combined salinity/stable-isotope analyses show large-scale sympathetic fluctuations that can be related to the origin of the parent water. Winter accretion represents half of the core length and mainly consists of frazil ice of normal sea-water origin. However, five major dilution events of sea water, with fresh-water input from the melting base of the ice shelf reaching 20% on two occasions, punctuate this winter accretion. Two of them correspond to platelet-ice production, which is often related to the freezing of ascending supercooled water from the bottom of the ice shelf.Brackish ice occurs between 450 and 530 cm in the core. It is demonstrated that this results from the freezing of brackish water (Jeffries and others, 1989) formed by mixing of normal sea water with melted basal shelf ice, with dilution percentages of maximum 80% fresh water.

Sign in / Sign up

Export Citation Format

Share Document