Cococubed.com Alpha-chain reaction networks
Home Astronomy Research    2024 Radiative Opacity    2024 Neutrino Emission from Stars    2023 White Dwarfs & 12C(α,γ)16O    2023 MESA VI    2022 Earendel, A Highly Magnified Star    2022 Black Hole Mass Spectrum    2021 Skye Equation of State    2021 White Dwarf Pulsations & 22Ne    Software Instruments      Stellar equation of states      EOS with ionization      EOS for supernovae      Chemical potentials      Stellar atmospheres      Voigt Function      Jeans escape      Polytropic stars      Cold white dwarfs      Adiabatic white dwarfs      Cold neutron stars      Stellar opacities      Neutrino energy loss rates      Ephemeris routines      Fermi-Dirac functions      Polyhedra volume      Plane - cube intersection      Coating an ellipsoid      Nuclear reaction networks      Nuclear statistical equilibrium      Laminar deflagrations      CJ detonations      ZND detonations      Fitting to conic sections      Unusual linear algebra      Derivatives on uneven grids      Pentadiagonal solver      Quadratics, Cubics, Quartics      Supernova light curves      Exact Riemann solutions      1D PPM hydrodynamics      Hydrodynamic test cases      Galactic chemical evolution      Universal two-body problem      Circular and elliptical 3 body      The pendulum      Phyllotaxis      MESA      MESA-Web      FLASH      Zingale's software      Brown's dStar      GR1D code      Iliadis' STARLIB database      Herwig's NuGRID      Meyer's NetNuc AAS Journals    2024 AAS YouTube    2024 AAS Peer Review Workshops 2024 ASU Energy in Everyday Life 2024 MESA Classroom Outreach and Education Materials Other Stuff:    Bicycle Adventures    Illustrations    Presentations Contact: F.X.Timmes my one page vitae, full vitae, research statement, and teaching statement.	13 isotopes This reaction network, aprox13.tar.xz, uses 13 isotopes in an alpha-chain from helium to nickel. Heavy-ion (12C+12C, 12C+16O, 16O+16O) are included. A definition of an α-chain reaction network seems prudent. A 'strict' α-chain is only composed of (α,γ) and (γ,α) links among the 13 isotopes 4He, 12C, 16O, 20Ne, 24Mg, 28Si, 32S, 36Ar, 40Ca, 44Ti, 48Cr, 52Fe, and 56Ni. It is essential, however, to include (α,p)(p,γ) and (γ,p)(p,α) links in order to obtain reasonably accurate energy generation rates and abundance levels when the temperature exceeds 2.5e9 K. At these elevated temperatures the flows through the (α,p)(p,γ) sequences are faster than the flows through the (α,γ) channels. An (α,p)(p,γ) sequence is, effectively, an (α,γ) reaction through an intermediate isotope. This α-chain reaction network includes 8 (α,p)(p,γ) sequences plus the corresponding inverse sequences by assuming steady-state proton flows through the intermediate isotopes 27Al, 31P, 35Cl, 39K, 43Sc, 47V, 51Mn, and 55Co. This strategy permits inclusion of (α,p)(p,γ) sequences without explicitly evolving the proton or intermediate isotope abundances. Jacobian A mild c+o burn 19 isotopes This network, aprox19.tar.xz, is the same network as the 13 isotope network above with additional isotopes to accommodate some types of hydrogen burning (PP chains and steady-state CNO cycles), along with some aspects of photodisintegration into 54Fe. This network is described in Weaver, Zimmerman, & Woosley. A strong c+o burn 21 isotopes This network, aprox21.tar.xz, adds 56Cr and 56Fe and equilibrium reaction sequences to the 19 isotope network to attain a lower Ye for presupernova models. This network is more-or-less the default workhorse network of MESA. Abundances and Ye evolution 34 isotopes This reaction network, hhe.tar.xz, combines the pp + hotcno + rp breakout network with the 13 isotope network above for a complete hydrogen + helium burner under most common conditions. 7 isotopes To decrease the execution time and memory it takes to calculate a stellar model means making a choice between having fewer isotopes in the reaction network or having less spatial resolution. The general response to this tradeoff has been to evolve a limited number of isotopes, and thus thus calculate an approximate thermonuclear energy generation rate. The 13 isotope network given above is commonly used for this purpose; one gets most of the energy generated for common thermodynamic conditions at a fraction of the computational cost. Can the number of isotopes be further reduced, and still give relatively accurate energy generation rates? Yes, within reason. This 7 isotope α-chain network, iso7.tar.xz, has been shown to provide a decent representation of nuclear energy generation rates for helium to silicon burning.
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