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I show that recent observations of r-process abundances in metal-poor stars are difficult to explain if neutron star mergers (NSMs) are the major r-process sources. In contrast, such observations and meteoritic data on Hf182 and I129 in the…

Astrophysics · Physics 2009-10-31 Y. -Z. Qian

Rapid neutron-capture (i.e., r-process) nucleosynthesis calculations, employing internally consistent and physically realistic nuclear physics input (QRPA beta-decay rates and the ETFSI-Q nuclear mass model), have been made. These…

The abundances of 92Nb and 146Sm in the early Solar System are determined from meteoritic analysis and their stellar production is attributed to the p process. We investigate if their origin from thermonuclear supernovae deriving from the…

Solar and Stellar Astrophysics · Physics 2016-02-17 Maria Lugaro , Marco Pignatari , Ulrich Ott , Kai Zuber , Claudia Travaglio , Gyorgy Gyurky , Zsolt Fulop

The heaviest chemical elements are naturally produced by the rapid neutron-capture process (r-process) during neutron star mergers or supernovae. The r-process production of elements heavier than uranium (transuranic nuclei) is poorly…

The rapid neutron-capture process or r-process is thought to produce the majority of the heavy elements (Z > 30) in extremely metal-poor stars. The same process is also responsible for a significant fraction of the heavy elements in the…

Solar and Stellar Astrophysics · Physics 2017-12-13 Andrew R. Casey , Kevin C. Schlaufman

Nanodiamonds (NDs) containing silicon vacancy (SiV) defects were evaluated as a potential biomarker for the labeling and fluorescent imaging of neural precursor cells (NPCs). SiV-containing NDs were synthesized using chemical vapor…

It is argued that the abundances of r-process related elements in stars with -3<[Fe/H]<-1 can be explained by the contributions of three sources. The sources are: the first generations of very massive (>100 solar masses) stars that are…

Astrophysics · Physics 2009-11-06 Y. -Z. Qian , G. J. Wasserburg

We investigate the possibility that inhomogeneous nucleosynthesis may eventually be used to explain the abundances of \li6, \be9 and B in population II stars. The present work differs from previous studies in that we have used a more…

We report C, N, Si, and Al-Mg isotope data for 39 presolar X silicon carbide (SiC) and four silicon nitride grains - a group of presolar grains that condensed in the remnants of core-collapse Type II supernovae (CCSNe) - isolated from the…

Solar and Stellar Astrophysics · Physics 2023-12-12 Nan Liu , Conel M. O'D. Alexander , Bradley S. Meyer , Larry R. Nittler , Jianhua Wang , Rhonda M. Stroud

Studies of nucleosynthesis in neutrino-driven winds from nascent neutron stars show that the elements from Sr through Ag with mass numbers A~88-110 are produced by charged-particle reactions (CPR) during the alpha-process in the winds.…

Astrophysics · Physics 2009-11-13 Y. -Z. Qian , G. J. Wasserburg

Diamond is a leading quantum photonics platform due to its ability to host qubits based on crystal defects such as nitrogen vacancy centres. Fabricating nanophotonic devices from defect-rich diamond, which is central to many quantum sensing…

Growing interests in neutron star (NS) mergers as the origin of r-process elements have sprouted since the discovery of evidence for the ejection of these elements from a short-duration gamma-ray burst. The hypothesis of a NS merger origin…

Astrophysics of Galaxies · Physics 2015-06-23 Takuji Tsujimoto , Toshikazu Shigeyama

We introduce a computational approach to estimate the hardness and stiffness of diamond surfaces and nanoparticles by studying their elastic response to atomic nanoindentation. Results of our ab initio density functional calculations…

Mesoscale and Nanoscale Physics · Physics 2020-02-28 Alexander Quandt , Igor Popov , David Tománek

A brief overview of the r-process is given with an emphasis on the observational implications for this process. The conditions required for the major production of the heavy r-process elements (r-elements) with mass numbers A >130 are…

Astrophysics · Physics 2008-09-18 Yong-Zhong Qian

We present a detailed chemical abundance analysis of HE 1300+0157, a subgiant with [Fe/H]=-3.9. From a high-resolution, high-S/N Subaru/HDS spectrum we find the star to be enriched in C ([C/Fe]_1D ~ +1.4) and O ([O/Fe]_1D ~ +1.8). With the…

We report abundance estimates for neutron-capture elements, including lead (Pb), and nucleosynthesis models for their origin, in two carbon-rich, very metal-poor stars, LP625-44 and LP706-7. These stars are subgiants whose surface…

Among presolar materials recovered in meteorites, abundant SiC and Al$_{2}$O$_{3}$ grains of AGB origins were found. They showed records of C, N, O, $^{26}$Al and s-element isotopic ratios that proved invaluable in constraining the…

Solar and Stellar Astrophysics · Physics 2015-06-18 M. Busso , O. Trippella , E. Maiorca , S. Palmerini

Renewed interest in the first stars that were formed in the universe has led to the discovery of extremely iron-poor stars. Since several competing scenarios exist, our understanding of the mass range that determines the observed elemental…

Astrophysics · Physics 2009-11-11 Takuji Tsujimoto , Toshikazu Shigeyama

The burgeoning field of nanophotonics has grown to be a major research area, primarily because of the ability to control and manipulate single quantum systems (emitters) and single photons on demand. For many years studying nanophotonic…

Quantum Physics · Physics 2014-08-26 Igor Aharonovich , Elke Neu

A sample of 895 s-process-rich candidates has been found among the 454180 giant stars surveyed by LAMOST at low spectral resolution (R~1800). In a previous study, taking advantage of the higher resolution (R~86 000) offered by the the…

Solar and Stellar Astrophysics · Physics 2023-09-06 D. Karinkuzhi , S. Van Eck , S. Goriely , L. Siess , A. Jorissen , A. Choplin , A. Escorza , S. Shetye , H. Van Winckel , .