Article
Geochemistry & Geophysics
Nan Liu, Nicolas Dauphas, Sergio Cristallo, Sara Palmerini, Maurizio Busso
Summary: This study presents new oxygen isotopic data for small presolar oxide grains and explores their origins and formation processes. The results suggest that Group 1 and Group 2 grains are likely derived from low-mass red giant stars and have experienced additional circulation processes. The study also reveals a higher proportion of Group 4 grains in the samples compared to previous literature.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2022)
Review
Astronomy & Astrophysics
Nan Liu, Sergio Cristallo, Diego Vescovi
Summary: Studying the isotopes of presolar grains, especially heavy element isotopes, is crucial for nuclear astrophysics. By analyzing the abundances in presolar grains, we can obtain independent and detailed constraints on stellar parameters.
Article
Astronomy & Astrophysics
Jordan Schofield, Marco Pignatari, Richard J. Stancliffe, Peter Hoppe
Summary: In this study, isotopic abundances of C, N, Al, Si, and Ti measured in presolar grains were compared with predictions from 21 CCSN models. The research found that high energy models favor the formation of a C/Si zone enriched in C-12, Si-28, and Ti-44.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
S. Q. Hou, C. Iliadis, M. Pignatari, J. B. Liu, T. C. L. Trueman, J. G. Li, X. X. Xu
Summary: The accurate evaluation of Ti-42(p,gamma)V-43 reaction rates is crucial for understanding the rp process in X-ray bursts. This study aimed to improve the rates using updated resonance parameters, direct S factor, and nuclear masses data. The results showed significant differences in the rates compared to previous estimations and confirmed the importance of the Ti-42(p,gamma)V-43 reaction path in the rp process.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Marta Molero, Laura Magrini, Francesca Matteucci, Donatella Romano, Marco Palla, Gabriele Cescutti, Carlos Viscasillas Vazquez, Emanuele Spitoni
Summary: We investigate the origin of neutron-capture elements in the Galactic thin disc by analysing their abundance patterns and radial gradients. Our detailed two-infall chemical evolution model includes nucleosynthesis prescriptions for neutron-capture elements and considers different synthesis sources. We compare our model predictions with data from the Gaia-ESO survey and find good agreement regarding the [Eu/Fe] versus [Fe/H] diagram and the [Fe/H] gradient slope. However, the predicted [Eu/H] radial gradient slope is steeper than observed, prompting discussion on Galaxy-formation scenarios and stellar radial migration effects. We also note slight underpredictions for Mo and Nd and successful reproduction of the [Pr/Fe] versus [Fe/H] trend.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Jose Nicolas Orce, Balaram Dey, Cebo Ngwetsheni, Srijit Bhattacharya, Deepak Pandit, Brenden Lesch, Andile Zulu
Summary: The abundances of heavy elements after iron are influenced by a process called rapid neutron capture or r-process. This process is influenced by the competition between neutron capture, photo-disintegration, and beta-decay rates, and is ultimately dependent on the binding energy of neutron-rich nuclei. Researchers have found that the symmetry energy, which describes the binding energy of ground states, is unexpectedly enhanced at higher temperatures. This enhancement may suggest a similar enhancement at lower temperatures where neutron capture occurs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
A. Choplin, S. Goriely, R. Hirschi, N. Tominaga, G. Meynet
Summary: The study investigates the mechanism of p-process nucleosynthesis in rotating massive stars and finds that rotation has a comparable impact on the p-process as on the s-process. The contribution of core-collapse supernovae from massive stars to the solar p-nuclei may have been underestimated in the past.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Sanjana Curtis, Philipp Mosta, Zhenyu Wu, David Radice, Luke Roberts, Giacomo Ricigliano, Albino Perego
Summary: In this study, we investigate r-process nucleosynthesis and kilonova emission resulting from binary neutron star mergers. We find that the wind from hypermassive neutron star remnants may be the dominant component producing the kilonova emission.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Projjwal Banerjee, Meng-Ru Wu, S. K. Jeena
Summary: GW170817 confirms binary neutron star mergers as one of the sites for rapid neutron capture (r-process). However, there are uncertainties in the nucleosynthesis calculations and additional sites may be needed to explain all observations. This study examines the abundance and evolution of short-lived radioactive isotopes (SLRIs) in the early Solar system and finds that I-129 and Cm-247 in the ESS do not solely come from a single major event, but have contributions from minor sources as well.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Geochemistry & Geophysics
S. A. Singerling, L. R. Nittler, J. Barosch, E. Dobrica, A. J. Brearley, R. M. Stroud
Summary: This study investigates six presolar grains in the ordinary chondrite Semarkona using transmission electron microscopy. The analysis reveals that SiC and spinel grains are stoichiometric and well crystallized, while the majority of silicate grains are non-stoichiometric and poorly crystallized. The findings provide important insights into the formation conditions and processes of presolar grains.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2022)
Article
Astronomy & Astrophysics
P. Krynski, L. Siess, A. Jorissen
Summary: This study proposes a fictitious network to approximate the synthesis of ls, hs, and vhs species in AGB stars with minimal computational expense. The network consists of seven fictitious particles assembled from elements with Z≥18, and their abundances and reaction rates are used to model the effective properties of the corresponding groups. The results show that the fictitious network reliably reproduces the abundances of ls, hs, and vhs species during the radiative s-process.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Linda Lombardo, Piercarlo Bonifacio, Patrick Francois, Camilla J. Hansen, Elisabetta Caffau, Michael Hanke, Asa Skuladottir, Almudena Arcones, Marius Eichler, Moritz Reichert, Athanasios Psaltis, Andreas J. Koch Hansen, Luca Sbordone
Summary: The CERES project aims to analyze the chemical evolution of metal-poor stars, presenting stellar parameters and chemical abundances for a sample of 52 giant stars. Findings include the identification of two zinc-rich stars and two stars with peculiar neutron-capture abundance patterns.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Multidisciplinary Sciences
A. Wallner, M. B. Froehlich, M. A. C. Hotchkis, N. Kinoshita, M. Paul, M. Martschini, S. Pavetich, S. G. Tims, N. Kivel, D. Schumann, M. Honda, H. Matsuzaki, T. Yamagata
Summary: By studying samples of Fe-60 and Pu-244 in Pacific Ocean crust, researchers have detected two influxes of 60Fe to Earth in the last 10 million years, accompanied by lower quantities of Pu-244. The similar Pu-244/Fe-60 influx ratios of both events suggest that supernovae explosions may not be the primary source of r-process nucleosynthesis.
Article
Astronomy & Astrophysics
Grethe Hystad, Asmaa Boujibar, Nan Liu, Larry R. Nittler, Robert M. Hazen
Summary: The study used various cluster analysis techniques to classify pre-solar silicon carbide grains, revealing that the grains could be divided into seven groups with high stability and good continuity in cluster assignments. Different types of grains come from different stellar origins.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Kurt Marti, Mario Fischer-Goedde, Carina Proksche
Summary: Anomalies in isotopic abundances of Mo and Ru in solar system matter were found to document variable contributions of the nucleosynthetic s-process component. The isotopic relationships between Mo-92 and Ru-100 in meteorites deviate from expected abundance variations, indicating the presence of distinct p-process components. The Mo and Ru isotopic records can help understand different explosive synthesis pathways and the galactic evolution of p-nuclides.
ASTROPHYSICAL JOURNAL
(2023)
Article
Geochemistry & Geophysics
Levke Koop, Kazuhide Nagashima, Andrew M. Davis, Alexander N. Krot
METEORITICS & PLANETARY SCIENCE
(2020)
Article
Multidisciplinary Sciences
J. Y. Hu, N. Dauphas, F. L. H. Tissot, R. Yokochi, T. J. Ireland, Z. Zhang, A. M. Davis, F. J. Ciesla, L. Grossman, B. L. A. Charlier, M. Roskosz, E. E. Alp, M. Y. Hu, J. Zhao
Summary: Research found that group II calcium-aluminum-rich inclusions are formed through a two-stage process involving fast evaporation and near-equilibrium recondensation, contrary to the expected scenario of equilibrium condensation. Calculated time scales are consistent with heating events similar to FU Orionis or EX Lupi-type outbursts of eruptive pre-main-sequence stars.
Article
Geochemistry & Geophysics
K. L. Villalon, K. K. Ohtaki, J. P. Bradley, H. A. Ishii, A. M. Davis, T. Stephan
Summary: Amorphous silicates with abundant nano-inclusions similar to cometary GEMS have been found in the Paris CM chondrite, but they have compositional and mineralogical differences. Additionally, Ni-rich sulfides are common in Paris but absent in cometary GEMS, suggesting a possible independent origin for the GEMS-like material in Paris.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2021)
Article
Geochemistry & Geophysics
Kenta K. Ohtaki, Hope A. Ishii, John P. Bradley, Krysten L. Villalon, Andrew M. Davis, Thomas Stephan, Karen C. Bustillo, Jim Ciston
Summary: The study compares GEMS-like material in Paris (CM) and Acfer 094 (ungrouped) chondrites with GEMS in anhydrous, chondritic interplanetary dust particles, revealing differences in amorphous silicate morphology and composition. The research suggests that GEMS-like material in Paris and Acfer 094 is not GEMS, and the presence of such amorphous silicates may not indicate high degrees of primitivity or pristinity in chondrite matrix samples. Further studies are recommended to search for presolar amorphous silicates in precharacterized chondrite matrix samples using transmission electron microscopy methods.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2021)
Article
Geochemistry & Geophysics
John P. Bradley, Hope A. Ishii, Karen Bustillo, James Ciston, Ryan Ogliore, Thomas Stephan, Donald E. Brownlee, David J. Joswiak
Summary: This study investigates the provenance of GEMS (glass with embedded metal and sulfides) in cometary type interplanetary dust particles using analytical scanning transmission electron microscopy and secondary ion mass spectrometry. The researchers find that GEMS have low densities and their elemental compositions and distributions are perturbed by contamination and secondary alteration. Oxygen isotope compositions are generally poor indicators of provenance, while nitrogen isotope compositions are more diagnostic. Based on all the observations, the authors conclude that GEMS are most likely processed interstellar silicates.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2022)
Article
Physics, Atomic, Molecular & Chemical
Thomas Stephan, Reto Trappitsch
Summary: The paper discusses the problem of correlated errors in experimental data and provides tools for propagating uncertainties in such cases. Techniques applicable to three-isotope plots in geo-and cosmochemistry are specifically discussed, where common denominators in isotope ratios and instrumental effects could lead to significant correlation of errors. The paper also compares various techniques for calculating linear regressions and suggests that the method proposed by Mahon (1996) [1] gives the best results after correcting some typographical errors and eliminating a minor mistake. A method for calculating linear regressions through a fixed point is also provided to avoid previous mistakes.
INTERNATIONAL JOURNAL OF MASS SPECTROMETRY
(2023)
Article
Physics, Nuclear
Nan Liu, Thomas Stephan, Sergio Cristallo, Diego Vescovi, Roberto Gallino, Larry R. Nittler, Conel M. O' D. Alexander, Andrew M. Davis
Summary: We report the Sr and Ba isotopic compositions of 18 presolar SiC grains, showing that Y and Z grains have higher Sr-88/Sr-87 ratios and more variable Ba-138/Ba-136 ratios compared to mainstream grains. Our findings suggest that the Y and Z grains originated from low-mass AGB stars, supporting previous research, although they fail to explain the indistinguishable Mo isotopic compositions.
EUROPEAN PHYSICAL JOURNAL A
(2022)
Meeting Abstract
Geochemistry & Geophysics
T. Stephan, H. E. Bloom, P. Hoppe, A. M. Davis, J. M. Korsmeyer, A. Regula, P. R. Heck, S. Amari
METEORITICS & PLANETARY SCIENCE
(2022)
Meeting Abstract
Geochemistry & Geophysics
N. Liu, T. Stephan, S. Cristallo, D. Vescovi, R. Gallino, L. R. Nittler, C. M. O'D. Alexander, A. M. Davis
METEORITICS & PLANETARY SCIENCE
(2022)
Meeting Abstract
Geochemistry & Geophysics
A. Regula, H. E. Bloom, N. Dauphas, A. M. Davis, J. M. Korsmeyer, M. J. Krawczynski, M. J. Pellin, S. Sheu, T. Stephan
METEORITICS & PLANETARY SCIENCE
(2021)
Meeting Abstract
Geochemistry & Geophysics
T. Stephan, H. E. Bloom, A. M. Davis, P. Hoppe, J. M. Korsmeyer, M. J. Pellin, A. Regula, S. Sheu
METEORITICS & PLANETARY SCIENCE
(2021)
Article
Astronomy & Astrophysics
Asmaa Boujibar, Samantha Howell, Shuang Zhang, Grethe Hystad, Anirudh Prabhu, Nan Liu, Thomas Stephan, Shweta Narkar, Ahmed Eleish, Shaunna M. Morrison, Robert M. Hazen, Larry R. Nittler
Summary: Cluster analysis of presolar silicon carbide grains based on various isotopic ratios revealed nine clusters representing different grain types, with mainstream grains mainly classified into three clusters possibly from stars of different metallicities. The inclusion of Al-26/Al-27 data highlighted a cluster enriched in N-15 and Al-26 not explainable by current models. This study also identified clusters of AB grains with excesses of N-15 and Al-26, pointing towards a need for more isotopic data for improved classification.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Astronomy & Astrophysics
Nan Liu, Thomas Stephan, Sergio Cristallo, Roberto Gallino, Patrick Boehnke, Larry R. Nittler, Conel M. O'D Alexander, Andrew M. Davis, Reto Trappitsch, Michael J. Pellin, Iris Dillmann
ASTROPHYSICAL JOURNAL
(2019)