Digital Commons Network^™

Adding Classical Novae Contribution To The Isotopic Scaling Model, Mengxi Chen

Macalester Journal of Physics and Astronomy

The Isotopic Scaling model(West & Heger, 2013) provides a complete average isotopic decomposition for our Milky Way as a function of metallicity and it requires an initial Solar Abundance Decomposition as a starting point. The previous Solar Abundance decomposition work is not perfect(West & Heger, 2013), since Classical Novae abundances are ignored. My research intends to improve the current solar abundance decomposition by adding Classical Novae Abundance contribution, then to update the Isotopic Scaling model.

R-Process Nucleosynthesis: Identifying The Significant Nuclear Properties, Sabina Gaia Tomasicchio

2023 REYES Proceedings

We provide a theoretical overview of r-process nucleosynthesis. We then identify the nuclear properties that have the greatest astrophysical impact according to recent sensitivity studies as: nuclear masses, β decays and neutron capture rates. Finally, we briefly discuss how the NuCRL model can enhance the performance of the relevant simulations.

Neutron Star Mergers And How To Study Them, Eric Burns

Faculty Publications

Neutron star mergers are the canonical multimessenger events: they have been observed through photons for half a century, gravitational waves since 2017, and are likely to be sources of neutrinos and cosmic rays.Studies of these events enable unique insights into astrophysics, particles in the ultrarelativistic regime, the heavy element enrichment history through cosmic time, cosmology, dense matter, and fundamental physics. Uncovering this science requires vast observational resources, unparalleled coordination, and advancements in theory and simulation, which are constrained by our current understanding of nuclear, atomic, and astroparticle physics. This review begins with a summary of our current knowledge of these …

Origin Of Chemical Elements From Water, Edward A. Boudreaux

Proceedings of the International Conference on Creationism

Based on a literal interpretation of the Biblical account of creation, it is inferred that all the original matter available to the universe was water (Gen. 1:1-3). Employing this premise, a method is outlined demonstrating how various chemical elements might have been derived via nucleosynthesis processes. The mechanism commences with the hydrogen (H) and oxygen (O) nuclei provided by water, which are subjected to nuclear reactions. These reactions invoke classical collision theory as the mechanism for generation of new atomic nuclei at a given steady-state temperature.

For purposes of simplicity and time constraints, the study thus far has been limited …

Collective Neutrino Flavor Oscillations In Multiple Dimensions And Scales, Joshua D. Martin

Physics & Astronomy ETDs

Hot and dense astrophysical environments such as the early universe, core collapse novae and binary neutron star mergers generate dense neutrino gases which can sub- sequently have an important effect on processes which occur in these environments. In this thesis we will present the results from several numerical simulations of these gases particularly in cases which are relevant to core collapse supernovae. These simulations employ fewer imposed spatial symmetries than those used in earlier works, and provide insight into behavior which may be expected to occur in three key regions of the explosion. We observe that when the neutrino gas …

Magnetic Structure And Radiative Captures Of Few-Nucleon Systems: Status And Prospects, Laura Elisa Marcucci, Rocco Schiavilla, Alex Gnech, Michele Viviani

Physics Faculty Publications

We review the main ingredients for an ab-initio study of few-nucleon reactions of astrophysical interest within the chiral effective field theory approach, with particular attention to radiative captures relevant for Big Bang Nucleosynthesis and stellar evolution. We conclude with an outlook for ongoing and future work.

Three-Dimensional Spectral Classification Of Low-Metallicity Stars Using Artificial Neural Networks, Shawn Snider, Ted Von Hippel, Et Al.

Ted von Hippel

We explore the application of artificial neural networks (ANNs) for the estimation of atmospheric parameters (T_eff, log g, and [Fe/H]) for Galactic F- and G-type stars. The ANNs are fed with medium-resolution (Δλ ~ 1-2 Å) non-flux-calibrated spectroscopic observations. From a sample of 279 stars with previous high-resolution determinations of metallicity and a set of (external) estimates of temperature and surface gravity, our ANNs are able to predict T_eff with an accuracy of σ(T_eff) = 135-150 K over the range 4250 ≤ T_eff ≤ 6500 K, log g with an accuracy …

Three-Dimensional Spectral Classification Of Low-Metallicity Stars Using Artificial Neural Networks, Shawn Snider, Ted Von Hippel, Carlos Allende Prieto, Timothy C. Beers, Christopher Sneden, Et Al.

Ted von Hippel

We explore the application of artificial neural networks (ANNs) for the estimation of atmospheric parameters (Teff, log g, and [Fe/H]) for Galactic F- and G-type stars. The ANNs are fed with medium-resolution (Δλ ~ 1-2 Å) non-flux-calibrated spectroscopic observations. From a sample of 279 stars with previous high-resolution determinations of metallicity and a set of (external) estimates of temperature and surface gravity, our ANNs are able to predict Teff with an accuracy of σ(Teff) = 135-150 K over the range 4250 ≤ Teff ≤ 6500 K, log g with an accuracy of σ(log …

Dynamical Compact Objects In Numerical Relativity, Hyun Lim

Theses and Dissertations

The work of this dissertation will study various aspects of the dynamics of compact objects using numerical simulations.We consider BH dynamics within two modified or alternative theories of gravity. Within a family of Einstein-Maxwell-Dilaton-Axion theories, we find that the GW waveforms from binary black hole (BBH) mergers differ from the standard GW waveform prediction of GR for especially large axion values. For more astrophysically realistic (i.e. smaller) values, the differences become negligible and undetectable. Weestablish the existence of a well-posed initial value problem for a second alternative theory fo gravity (quadratic gravity) and demonstrate in spherical symmetry that a linear …

Finding The Remnants Of The Milky Way's Last Neutron Star Mergers, Meng Ru Wu, Projjwal Banerjee, Brian D. Metzger, Gabriel Martínez-Pinedo, Tsuguo Aramaki, Eric Burns, Charles J. Hailey, Jennifer Barnes, Georgia Karagiorgi

Faculty Publications

The discovery of a binary neutron star merger (NSM) through both its gravitational wave and electromagnetic emission has revealed these events to be key sites of r-process nucleosynthesis. Here, we evaluate the prospects of finding the remnants of Galactic NSMs by detecting the gamma-ray decay lines from their radioactive r-process ejecta. We find that 126Sn, which has several lines in the energy range 415-695 keV and resides close to the second r-process peak, is the most promising isotope, because of its half-life t 1/2 = 2.30(14) 105 yr being comparable to the ages of recent NSMs. Using a Monte Carlo …

White Paper On Nuclear Astrophysics And Low Energy Nuclear Physics Part 1: Nuclear Astrophysics, Almudena Arcones, Dan W. Bardayan, Timothy C. Beers, Lee A. Bernstein, Jeffrey C. Blackmon, Bronson Messer, B. Alex Brown, Edward F. Brown, Carl R. Brune, Art E. Champagne, Alessandro Chieffi, Aaron J. Couture, Pawel Danielewicz, Roland Diehl, Mounib El-Eid, Jutta E. Escher, Brian D. Fields, Carla Fröhlich, Falk Herwig, William Raphael Hix, Christian Iliadis, William G. Lynch, Gail C. Mclaughlin, Bradley S. Meyer, Anthony Mezzacappa, Filomena Nunes, Brian W. O'Shea, Madappa Prakash, Boris Pritychenko, Sanjay Reddy, Ernst Rehm, Grigory Rogachev, Robert E. Rutledge

Faculty Publications

This white paper informs the nuclear astrophysics community and funding agencies about the scientific directions and priorities of the field and provides input from this community for the 2015 Nuclear Science Long Range Plan. It summarizes the outcome of the nuclear astrophysics town meeting that was held on August 21–23, 2014 in College Station at the campus of Texas A&M University in preparation of the NSAC Nuclear Science Long Range Plan. It also reflects the outcome of an earlier town meeting of the nuclear astrophysics community organized by the Joint Institute for Nuclear Astrophysics (JINA) on October 9–10, 2012 Detroit, …

Determining The 14O(Α,P)17F Astrophysical Rate From Measurements At Twinsol, D. W. Bardayan, T. Ahn, J. M. Allen, M. Brodeur, B. Frentz, Y. K. Gupta, M. R. Hall, O. Hall, S. Henderson, J. Hu, J. M. Kelly, J. J. Kolata, A. Long, C. Nicoloff, P. D. O'Malley, K. Ostdiek, M. K. Smith, S. Strauss, F. D. Becchetti, J. Riggins, R. O. Torres-Isea, J. C. Blackmon, K. Macon, K. A. Chipps, S. D. Pain, A. M. Rogers

Faculty Publications

The 14O(α,p)17F reaction is an important trigger reaction to the α-p process in X-ray bursts. The most stringent experimental constraints on its astrophysical rate come from measurements of the time-inverse reaction, 17F(p,α)14O. Previous studies of this inverse reaction have sufficiently characterized the high-energy dependence of the cross section but there are still significant uncertainties at lower energies. A new measurement of the 17F(p,α)14O cross section is underway at the Twin Solenoid (TwinSol) facility at the University of Notre Dame using an in-flight secondary 17F beam. The initial results are promising but improvements are needed to complete the measurement. The initial …

Correlated Xanes, Tem, And Nanosims Of Presolar Graphite Grains, Evan E. Groopman, Larry R. Nittler

U.S. Navy Research

We report correlated XANES, TEM, and NanoSIMS measurements of twelve presolar graphite grains extracted from primitive meteorites and for which isotopic data indicate predominantly Type-II supernovae origins. We find continued evidence for isotopic heterogeneities in presolar graphite grains, including the first observation of a radial gradient in the inferred initial ²⁶Al/²⁷Al within a presolar graphite grain. The XANES spectra of these samples show a variety of minor absorbances near the C K-edge, attributable to vinyl-keto, aliphatic, carboxyl, and carbonate molecules, as well as possible damage during sample preparation. Each sample exhibits homogeneous C K-edge XANES spectra within …

The New Jensa Gas-Jet Target For Astrophysical Radioactive Beam Experiments, D. W. Bardayan, K. A. Chipps, S. Ahn, J. C. Blackmon, J. Browne, U. Greife, K. L. Jones, A. Kontos, R. L. Kozub, L. Linhardt, B. Manning, M. Matoš, P. D. O'Malley, F. Montes, S. Ota, S. D. Pain, W. A. Peters, S. T. Pittman, A. Sachs, H. Schatz, K. T. Schmitt, M. S. Smith, P. Thompson

Faculty Publications

To take full advantage of advanced exotic beam facilities, target technology must also be advanced. Particularly important to the study of astrophysical reaction rates is the creation of localized and dense targets of hydrogen and helium. The Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas-jet target has been constructed for this purpose. JENSA was constructed at Oak Ridge National Laboratory (ORNL) where it was tested and characterized, and has now moved to the ReA3 reaccelerated beam hall at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University for use with radioactive beams.

Structure And Stability Of Primordial Stars, Aysel İbrahi̇m Karafi̇stan

Turkish Journal of Physics

For decades large-scale cosmic structures have been modeled as the gravitational amplification of small-density perturbations of the cosmological recombination epoch of the Big Bang. In astrophysics, cosmological nucleosynthesis is considered responsible for the production of the pristine gas, which should be found in the first-generation stars in the form of hydrogen and helium as the main constituents. In the later type of second-generation stars, hydrogen is converted into helium by the CN-cycle reactions, in which heavier elements are produced. These elements are believed to enrich the intergalactic medium by possible star bursts at the last stages of evolution. Stability criteria …

The First Science Result With The Jensa Gas-Jet Target: Confirmation And Study Of A Strong Subthreshold 18F(P,Α)15O Resonance, D. W. Bardayan, K. A. Chipps, S. Ahn, J. C. Blackmon, R. J. Deboer, U. Greife, K. L. Jones, A. Kontos, R. L. Kozub, L. Linhardt, B. Manning, M. Matoš, P. D. O'Malley, S. Ota, S. D. Pain, W. A. Peters, S. T. Pittman, A. Sachs, K. T. Schmitt, M. S. Smith, P. Thompson

Faculty Publications

The astrophysical 18F(p,α)15O rate determines, in large part, the extent to which the observable radioisotope 18F is produced in novae. This rate, however, has been extremely uncertain owing to the unknown properties of a strong subthreshold resonance and its possible interference with higher-lying resonances. The new Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas-jet target has been used for the first time to determine the spin of this important resonance and significantly reduce uncertainties in the 18F(p,α)15O rate.

Nucleosynthesis In Self-Consistent Core-Collapse Supernova Models Using Multidimensional Chimera Simulations, James Austin Harris

Doctoral Dissertations

Observations of nuclear abundances in core-collapse supernova (CCSN) ejecta, highlighted by γ-ray [gamma-ray] observations of the ⁴⁴Ti [titanium-44] spatial distribution in the nearby supernova remnants Cassiopeia A and SN 1987A, allow nucleosynthesis calculations to place powerful constraints on conditions deep in the interiors of supernovae and their progenitor stars. This ability to probe where direct observations cannot makes such calculations an invaluable tool for understanding the CCSN mechanism. Unfortunately, despite knowing for two decades that supernovae are intrinsically multi-dimensional events, discussions of CCSN nucleosynthesis have been predominantly based on spherically symmetric (1D) models, which employ a contrived energy source …

Galactic Chemical Evolution And Nucleocosmochronology: Standard Model With Terminated Infall, Donald D. Clayton

Donald D Clayton

Some exactly soluble families of models for the chemical evolution of the Galaxy are presented. The parameters considered include gas mass, the age-metallicity relation, the star mass vs. metallicity, the age distribution, and the mean age of dwarfs. A short BASIC program for calculating these parameters is given. The calculation of metallicity gradients, nuclear cosmochronology, and extinct radioactivities is addressed. An especially simple, mathematically linear model is recommended as a standard model of galaxies with truncated infall due to its internal consistency and compact display of the physical effects of the parameters.

An Interpretation Of Special And General Isotopic Anomolies In R-Process Nuclei, Donald D. Clayton

Donald D Clayton

My analysis of new discoveries by McCulloch and Wasserburg of Ba and Nd isotopic anomalies in inclusions of the Allende meteorite argues that (1) these anomalies contain special extinct radioactivities resulting from radioactive decay within grains formed in and ejected from the supernova interior, (2) the inclusions studied are fused assemblies of interstellar grains that were never totally vaporized, and (3) theoretical separation into r and s abundances suggests that fluctuations between r and s components has occurred during the accumulation processes. These points lend support to a new chemical picture of the early solar system that I have developed, …

Author's Reply: Extinct Radioactivities As Trapped Residuals Of Presolar Grains, Donald D. Clayton

Donald D Clayton

Trivedi's attempted disproof of presolar grains as carriers of special 129Xe* in meteorites is rejected on three grounds: (1) the high-T losses of 129Xe* and 1271 are tightly correlated, (2) the sharply isochronous meteorites are partially differentiated but not truly metamorphosed, and (3) evidence that much of solar 129Xe was trapped in presolar grains has strengthened the plausibility of the presolar-grain picture.

Origin Of Heavy Xenon In Meteoritic Diamonds, Donald D. Clayton

Donald D Clayton

The neutrino burst from the collapsed core in Type II supernovae liberates free neutrons by nu, nu-prime(n) reactions which drive isotopic abundances several mass steps heavier. The neutron fluence in the He shell, abetted by another burst 10 s later from alpha, n reactions, is about right for rendering Xe-136, the most abundant Xe isotope. The Xe isotopic composition is a good match to Xe-H, the unshielded neutron-rich Xe component abundant in carbonaceous meteorites. The He shell is implicated because it is the only C-rich shell in massive stars that can be expected to condense solid carbon thermally, a requirement …

Stochastic Evolution Of Refractory Interstellar Dust During The Chemical Evolution Of A Two-Phase Interstellar Medium, Kurt Liffman, Donald D. Clayton

Donald D Clayton

The evolution course of refractory interstellar dust during the chemical evolution of a two-phase interstellar medium (ISM) is studied using a simple model of the chemical evolution of ISM. It is assumed that, in this medium, the stars are born in molecular clouds, but new nucleosynthesis products and stellar return are entered into a complementary diffuse medium; the well-mixed matter of each interstellar phase is repeatedly cycled stochastically through the complementary phase and back. The dust is studied on a particle-by-particle bases as it is sputtered by shock waves in the diffuse medium, accretes an amorphous mantle of gaseous refractory …

S-Process Studies: Exact Solution To A Chain Having Two Distinct Cross-Section Values, Donald D. Clayton, Michael J. Newman

Donald D Clayton

We present the exact solution to an s-process chain having two distinct values for the cross-sections. The comparison of this exact solution with the CFHZ approximate solution to the same problem reveals that approximate solution to be adequate for most astrophysical problems.

Theory Of Quasi-Equilibrium Nucelosynthesis And Applications To Matter Expanding From High Temperature And Density, Bradley S. Meyer, Tracy D. Krishnan, Donald D. Clayton

Donald D Clayton

Our first purpose is construction of a formal theory of quasi-equilibrium. We define quasi-equilibrium, in its simplest form, as statistical equilibrium in the face of an extra constraint on the nuclear populations. We show that the extra constraint introduces a uniform translation of the chemical potentials for the heavy nuclei and derive the abundances in terms of it. We then generalize this theory to accommodate any number of constraints. For nucleosynthesis, the most important constraint occurs when the total number of heavy nuclei Yh within a system of nuclei differs from the number that would exist in nuclear statistical equilibrium …

On The E-Process: Its Components And Their Neutron Excesses, Kem L. Hainebach, Donald D. Clayton, W David Arnett, S E. Woosley

Donald D Clayton

The pattern of abundances within the iron-abundance peak of the solar system is analyzed for various Cr, Fe, and Ni abundances, and a method is developed for finding the best fit to a given set of abundances with a chosen number of zones, i.e., mass contributions characterized by differing values of eta. This material can be synthesized by a superposition of e-process compositions in a low-eta region (eta = 0.003) and a high-eta region (eta = 0.065 -0.080) with at least 85% coming from the low-eta region. Addition of a third eta zone is unproductive. The applicability of the particle-poor …

A New Interpretation Of 26al In Meteoritic Inclusions, Donald D. Clayton, Liping Jin

Donald D Clayton

We suggest that the large 26Al/27Al ϭ 5 ϫ 10Ϫ5 abundance ratio found in calcium-aluminum–rich inclusions (CAIs) in meteorites is produced by energetic particle irradiation in the early solar system but only in a thin (0.2 g cmϪ2) skin of the solar preplanetary disk that stops the energetic particles. Buildup of that 26Al concentration happens only during the quiescent, or passive, phase of the solar disk, after accretion and associated turbulence has ceased. We propose that CAIs also originate in the form of fine Al-rich dust within a coronal-type environment atop the disk. In this model only the CAIs among …

Positron Annihilation Gamma Rays From Novae, M D. Leising, Donald D. Clayton

Donald D Clayton

The potential for observing annihilation gamma rays from novae is investigated. These gamma rays, a unique signature of the thermonuclear runaway models of novae, would result from the annihilation of positrons emitted by beta(+)-unstable nuclei produced near the peak of the runaway and carried by rapid convection to the surface of the nova envelope. Simple models, which are extensions of detailed published models, of the expansion of the nova atmospheres are evolved. These models serve as input into investigations of the fate of nearby Galactic fast novae could yield detectable fluxes of electron-positron annihilation gamma rays produced by the decay …

S-Process Studies: Exact Evaluation Of An Exponential Distrubution Of Exposures, Donald D. Clayton, Richard A. Ward

Donald D Clayton

We show that the solution of the s-process chain can be easily evaluated exactly if the seed nuclei have been irradiated with an exponential distribution of exposures. For the same distribution of exposures, the shape of the akNk curve past the last seed is independent of the distribution of seed nuclei. Evaluation of these results confirms the accuracy of the well-known CFHZ approximation.

Galactic Chemical Evolution: Z Versus In(1/Mu) Relationship, Donald D. Clayton

Donald D Clayton

The ways in which a radial abundance gradient in a disk galaxy may be interpreted are reexamined, asking how metallicity Z depends upon gas mass fraction mu in analytic models characterized by a temporally varying history of metal-poor infall. Six different such models are studied, and it is shown that the metallicity versus gas fraction relationship is well approximated by an expression which is the analog of the Z = y ln(1/mu) relation for closed evolution. The approximation appears valid when the infall rate is nonneglible, but not so great that it dominates the gas budget.

Gamma-Ray Emission And Nucleosynthesis Of Lithium By Young Pulsars, Donald D. Clayton, Eliahu Dwek

Donald D Clayton

We propose that 7Li is produced in the Galaxy primarily by α-α collisions surrounding newly born pulsars. About 10 percent of the pulsar energy losses are converted to medium-energy α-particles which collide in a dominantly He nebula. The problem of the origin of lithium would be solved by the scenario, and clear-cut tests by nuclear γ-ray astronomy are described.