Stellar physics and evolution calculations enable a broad range of research in astrophysics. Modules for Experiments in Stellar Astrophysics (MESA) is a suite of open source, robust, efficient, thread-safe libraries for a wide range of applications in computational stellar astrophysics. A one-dimensional stellar evolution module, MESAstar, combines many of the numerical and physics modules for simulations of a wide range of stellar evolution scenarios ranging from very low mass to massive stars, including advanced evolutionary phases. MESAstar solves the fully coupled structure and composition equations simultaneously. It uses adaptive mesh refinement and sophisticated timestep controls, and supports shared memory parallelism based on OpenMP. State-of-the-art modules provide equation of state, opacity, nuclear reaction rates, element diffusion data, and atmosphere boundary conditions. Each module is constructed as a separate Fortran 95 library with its own explicitly defined public interface to facilitate independent development. Several detailed examples indicate the extensive verification and testing that is continuously performed and demonstrate the wide range of capabilities that MESA possesses. These examples include evolutionary tracks of very low mass stars, brown dwarfs, and gas giant planets to very old ages; the complete evolutionary track of a 1 M ☉ star from the pre-main sequence (PMS) to a cooling white dwarf; the solar sound speed profile; the evolution of intermediate-mass stars through the He-core burning phase and thermal pulses on the He-shell burning asymptotic giant branch phase; the interior structure of slowly pulsating B Stars and Beta Cepheids; the complete evolutionary tracks of massive stars from the PMS to the onset of core collapse; mass transfer from stars undergoing Roche lobe overflow; and the evolution of helium accretion onto a neutron star. MESA can be downloaded from the project Web site (http://mesa.sourceforge.net/).

https://iopscience.iop.org/article/10.1088/0067-0049/192/1/3/pdf

Modules for Experiments in Stellar Astrophysics (MESA)

We present the updated version of the code used to compute stellar evolutionary tracks in Padova. It is the result of a thorough revision of the major in put physics, together with the inclusion of the pre‐main sequence phase, not present in our previous releases of stellar models. Another innovative aspect is the possibility of prompt ly generating accurate opacity tables fully consistent with any selected initial chemical composition, by coupling the OPAL opacity data at high temperatures to the molecular opacities computed with our AESOPUS code (Marigo & Aringer 2009). In this work we present extended sets of stellar evolutionary models for various initial chemical compositions, while other set s with different metallicities and/or different distributions of heavy elements are being computed. For the present release of models we adopt the solar distribution of heavy elements from the recent revision by Caffau et al. (2011), corresponding to a Sun’s metallicity Z≃ 0.0152. From all computed sets of stellar tracks, we also derive isochrones in several photometric systems. The aim is to provide the community with the basic tools to model star clusters and galaxies by means of population synthesis techniques.

parsec: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code

We present the updated version of the code used to compute stellar evolutionary tracks in Padova. It is the result of a thorough revision of the major input physics, together with the inclusion of the pre-main sequence phase, not present in our previous releases of stellar models. Another innovative aspect is the possibility of promptly generating accurate opacity tables fully consistent with any selected initial chemical composition, by coupling the OPAL opacity data at high temperatures to the molecular opacities computed with our AESOPUS code (Marigo & Aringer 2009). In this work we present extended sets of stellar evolutionary models for various initial chemical compositions, while other sets with different metallicities and/or different distributions of heavy elements are being computed. For the present release of models we adopt the solar distribution of heavy elements from the recent revision by Caffau et al. (2011), corresponding to a Sun's metallicity Z=0.0152. From all computed sets of stellar tracks, we also derive isochrones in several photometric systems. The aim is to provide the community with the basic tools to model star clusters and galaxies by means of population synthesis techniques.

PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code

The ever-expanding depth and quality of photometric and spectroscopic observations of stellar populations increase the need for theoretical models in regions of age-composition parameter space that are largely unexplored at present. Stellar evolution models that employ the most advanced physics and cover a wide range of compositions are needed to extract the most information from current observations of both resolved and unresolved stellar populations. The Dartmouth Stellar Evolution Database is a collection of stellar evolution tracks and isochrones that spans a range of [Fe/H] from –2.5 to +0.5, [α/Fe] from –0.2 to +0.8 (for [Fe/H] ≤ 0) or +0.2 (for [Fe/H] > 0), and initial He mass fractions from Y = 0.245 to 0.40. Stellar evolution tracks were computed for masses between 0.1 and 4 M☉, allowing isochrones to be generated for ages as young as 250 Myr. For the range in masses where the core He flash occurs, separate He-burning tracks were computed starting from the zero age horizontal branch. The tracks and isochrones have been transformed to the observational plane in a variety of photometric systems including standard UBV(RI)C, Stromgren uvby, SDSS ugriz, 2MASS JHKs, and HST ACS/WFC and WFPC2. The Dartmouth Stellar Evolution Database is accessible through a Web site at http://stellar.dartmouth.edu/~models/ where all tracks, isochrones, and additional files can be downloaded.

https://iopscience.iop.org/article/10.1086/589654/pdf

The Dartmouth Stellar Evolution Database

amount of energy, a tiny fraction of which is sufficient to explode the star as a supernova. The authors examine our current understanding of the lives and deaths of massive stars, with special attention to the relevant nuclear and stellar physics. Emphasis is placed upon their post-helium-burning evolution. Current views regarding the supernova explosion mechanism are reviewed, and the hydrodynamics of supernova shock propagation and ‘‘fallback’’ is discussed. The calculated neutron star masses, supernova light curves, and spectra from these model stars are shown to be consistent with observations. During all phases, particular attention is paid to the nucleosynthesis of heavy elements. Such stars are capable of producing, with few exceptions, the isotopes between mass 16 and 88 as well as a large fraction of still heavier elements made by the r and p processes.

/pdf/the-evolution-and-explosion-of-massive-stars-57jc6k6s1i.pdf

The evolution and explosion of massive stars

A compilation of charged-particle induced thermonuclear reaction rates

The excitation of nuclear states by electric and magnetic multipole transitions of bound electrons in the presence of a strong laser field is studied. The excitation probability is calculated for general time-dependent electronic states in first-order perturbation theory. An adiabatic description of the dressed electron states in the laser field allows an easy calculation of the excitation function. Ionization effects caused by the laser are considered in a simple manner. The probability for the excitation of the nuclei $_{66}^{161}\mathrm{Dy}$, $_{76}^{189}\mathrm{Os}$, $_{77}^{193}\mathrm{Ir}$, $_{79}^{197}\mathrm{Au}$, $_{92}^{235}\mathrm{U}$, and $_{93}^{237}\mathrm{Np}$ is investigated as a function of the laser intensity and the photon energy. The increase of the excitation probability is limited by the ionization of the atom and the lifetime of the states. The de-excitation of the 3/${2}^{+}$ (3.5\ifmmode\pm\else\textpm\fi{}1.0 eV) state in $_{90}^{229}\mathrm{Th}$ is an example of the laser-assisted discrete internal conversion. \textcopyright{} 1996 The American Physical Society.

Nuclear excitation by laser-assisted electronic transitions

A simple wave-mechanical argument is used to separate the nuclear and Coulomb rainbow components from the experimental differential cross-section of elastic alpha and light composite particle-nucleus scattering at intermediate energies We also show, through semi-classical arguments, how the nuclear rainbow component can be interpreted as a refractive effect due to the nuclear forces

https://link.springer.com/content/pdf/10.1007/BF01411831.pdf

On the separation of the nuclear and Coulomb rainbow components from the elastic scattering data

A practical solution of the inversion problem using the quasi-classical limit of the high-energy approximation is reported. The method is successfully applied to the system 16O+12C at 1503 MeV.

Nucleus-nucleus potential from the scattering data by quasi-classical inversion

The study of the hyperfine anomaly of neutron rich nuclei, in particular, neutron halo nuclei, can give a very specific and unique way to measure their neutron distribution and confirm a halo structure. The hyperfine structure anomaly in ${\text{Be}}^{+}$ ions is calculated with a realistic electronic wave function, obtained as a solution of the Dirac equation. In the calculations, the Coulomb potential modified by the charge distribution of the clustered nucleus and three electrons in the $1{s}^{2}2s$ configuration is used. The nuclear wave function is obtained in the core+nucleon model of $^{9,11}\mathrm{Be}$. The aim of this study is to test whether the hyperfine structure anomaly reflects a halo structure in $^{11}\mathrm{Be}$.

Ch. Leclercq-Willain

Papers

A compilation of charged-particle induced thermonuclear reaction rates

Nuclear excitation by laser-assisted electronic transitions

On the separation of the nuclear and Coulomb rainbow components from the elastic scattering data

Nucleus-nucleus potential from the scattering data by quasi-classical inversion

Hyperfine anomaly in Be isotopes in the cluster model and the neutron spatial distribution