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| Seven Isotope Alpha-Chain |
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J.D. Maldonado
F.X.Timmes, my vitae
To decrease the computer 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 set of 13 nuclei most commonly used for this purpose are 4He, 12C, 16O, 20Ne, 24Mg, 28Si, 32S, 36Ar, 40Ca, 44Ti, 48Cr, 52Fe, and 56Ni. In essence, one gets most of the energy generated for most thermodynamic conditions at a fraction of the computational cost (memory + CPU).
Can the number of isotopes be further reduced, and still give relatively accurate energy generation rates?
Yes, within reason. The 7 isotope alpha-chain network given below is presented in "An Inexpensive Nuclear Energy Generation Network For Stellar Hydrodynamics". This network is shown to give a good representation of nuclear energy generation rates during helium, carbon, neon, and oxygen burning. It even gives reasonable estimates for the energy generation rates during silicon burning and photodisintegration reactions. Thus, this network may be useful for exploratory multi-dimensional calculations where large reaction networks are impractical even on the largest parallel supercomputers.
7 vs 13 isotopes |
7 vs 490 isotopes |
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public_iso7.f plus these include files: burn_common.dek cjdet.dek const.dek implno.dek network.dek sparse_matrix.dek tfactors.dek timers.dek vector_eos.dek plus a 13 MB eos data file : helm_table.dat |