Publications (21)
Large collection of astrophysical S-factors and its compact representation
A. V. Afanasjev, M. Beard, A. I. Chugunov +2
Numerous nuclear reactions in the crust of accreting neutron stars are strongly affected by dense plasma environment. Simulations of superbursts, deep crustal heating and other nuc…
Measurement of the reaction O-17(α,n)Ne-20 and its impact on the s process in massive stars
A. Best, M. Beard, J. Görres +16
The ratio between the rates of the reactions O-17(α,n)Ne-20 and O-17(α,γ)Ne-21 determines whether O-16 is an efficient neutron poison for the s process in massive stars, or if m…
Neutron degeneracy and plasma physics effects on radiative neutron captures in neutron star crust
P. S. Shternin, M. Beard, M. Wiescher +1
We consider the astrophysical reaction rates for radiative neutron capture reactions () in the crust of a neutron star. The presence of degenerate neutrons at high densities…
Fusion reactions in multicomponent dense matter
D. G. Yakovlev, L. R. Gasques, M. Beard +2
We analyze thermonuclear and pycnonuclear fusion reactions in dense matter containing atomic nuclei of different types. We extend a phenomenological expression for the reaction rat…
The first direct measurement of 12C(12C,n)23Mg at stellar energies
B. Bucher, X. D. Tang, X. Fang +28
Neutrons produced by the carbon fusion reaction 12C(12C,n)23Mg play an important role in stellar nucleosynthesis. However, past studies have shown large discrepancies between exper…
Impact of Pycnonuclear Fusion Uncertainties on the Cooling of Accreting Neutron Star Crusts
R. Jain, E. F. Brown, H. Schatz +11
The observation of X-rays during quiescence from transiently accreting neutron stars provides unique clues about the nature of dense matter. This, however, requires extensive model…
Astrophysical S-factors for fusion reactions involving C, O, Ne and Mg isotopes
M. Beard, A. V. Afanasjev, L. C. Chamon +3
Using the Sao Paulo potential and the barrier penetration formalism we have calculated the astrophysical factor S(E) for 946 fusion reactions involving stable and neutron-rich isot…
Nuclear masses near that influence -process abundances
M. Mumpower, R. Surman, M. Beard +2
Nuclear masses are one of the key ingredients of nuclear physics that go into astrophysical simulations of the process. Nuclear masses effect -process abundances by entering…
Nuclear Reactions in the Crusts of Accreting Neutron Stars
R. Lau, M. Beard, S. S. Gupta +13
X-ray observations of transiently accreting neutron stars during quiescence provide information about the structure of neutron star crusts and the properties of dense matter. Inter…
A simple analytic model for astrophysical S-factors
D. G. Yakovlev, M. Beard, L. R. Gasques +1
We propose a physically transparent analytic model of astrophysical S-factors as a function of a center-of-mass energy E of colliding nuclei (below and above the Coulomb barrier) f…
Low-Energy Magnetic Radiation
S. Frauendorf, M. Beard, M. Mumpower +2
A pronounced spike at low energy in the strength function for magnetic radiation (LEMAR) is found by means of Shell Model calculations, which explains the experimentally observed e…
Time-of-flight mass measurements for nuclear processes in neutron star crusts
A. Estrade, M. Matos, H. Schatz +23
The location of electron capture heat sources in the crust of accreting neutron stars depends on the masses of extremely neutron-rich nuclei. We present first results from a new im…
Crust composition and the Shallow Heat Source in KS 1731-260
R. Jain, E. F. Brown, H. Schatz +11
The presence of a strong shallow heat source of unknown origin in accreting neutron star crusts has been inferred by analyzing X-ray observations of their cooling in quiescence. We…
The evolution of the UV/optical lag spectrum of NGC 7469 seen by the Liverpool Telescope
F. M. Vincentelli, M. Beard, I. Mc Hardy +3
We present the results regarding the analysis of an intensive monitoring of the Active Galactic Nucleus (AGN) NGC 7469. We observed the source for 4 months with almost daily cadenc…
The impact of nuclear masses near on -process abundances
M. Mumpower, D. -L. Fang, R. Surman +2
We have performed for the first time a complete -process mass sensitivity study in the region. We take into account how an uncertainty in a single nuclear mass propagates…
The impact of individual nuclear masses on -process abundances
M. R. Mumpower, R. Surman, D. -L. Fang +4
We have performed for the first time a comprehensive study of the sensitivity of -process nucleosynthesis to individual nuclear masses across the chart of nuclides. Using the la…
First detection of the outer edge of an AGN accretion disc: Very fast multiband optical variability of NGC 4395 with GTC/HiPERCAM and LT/IO:O
I. M. McHardy, M. Beard, E. Breedt +11
We present fast (~200s sampling) ugriz photometry of the low mass AGN NGC 4395 with the Liverpool Telescope, followed by very fast (3s sampling) us, gs, rs, is and zs simultaneous…
The 12C + 12C reaction and the impact on nucleosynthesis in massive stars
M. Pignatari, R. Hirschi, M. Wiescher +7
Despite much effort in the past decades, the C-burning reaction rate is uncertain by several orders of magnitude, and the relative strength between the different channels 12C(12C,a…
Propagation of Hauser-Feshbach uncertainty estimates to r-process nucleosynthesis: Benchmark of statistical property models for neutron rich nuclei far from stability
S. Nikas, G. Perdikakis, M. Beard +3
Multimessenger observations of the neutron star merger event GW170817 have re-energized the debate over the astrophysical origins of the most massive elements via the r-process nuc…
Nuclear fusion in dense matter: Reaction rate and carbon burning
L. R. Gasques, A. V. Afanasjev, E. F. Aguilera +5
In this paper we analyze the nuclear fusion rate between equal nuclei for all five different nuclear burning regimes in dense matter (two thermonuclear regimes, two pycnonuclear on…
Constraining the S factor of 15N(p,g)16O at Astrophysical Energies
P. J. LeBlanc, G. Imbriani, J. Goerres +44
The 15N(p,g)16O reaction represents a break out reaction linking the first and second cycle of the CNO cycles redistributing the carbon and nitrogen abundances into the oxygen rang…