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Home Astronomy research   Software Infrastructure:      MESA      FLASH-X      STARLIB      MESA-Web      starkiller-astro      My instruments   Neutrino Emission:      De-excitation Neutrinos      Neutrino emission from stars      Identifying the Pre-SN      Neutrino HR diagram      Pre-SN Beta Processes      Pre-SN neutrinos   White dwarf pulsations:      12C(α,γ) & overshooting      Probe of 12C(α,γ)16O      Impact of 22Ne      Impact of ν cooling      Variable white dwarfs      MC reaction rates      Micronovae      Novae   White dwarf supernova:      Stable nickel production      Remnant metallicities      Colliding white dwarfs      Merging white dwarfs      Ignition conditions      Metallicity effects      Central density effects      Detonation density      Tracer particle burning      Subsonic burning fronts      Supersonic fronts      W7 profiles   Massive stars:      Pop III with HST/JWST      Rotating progenitors      3D evolution to collapse      MC reaction rates      Pre-SN variations   Massive star supernova:      Yields of radionuclides      26Al & 60Fe      44Ti, 60Co & 56Ni      SN 1987A light curve      Constraints on Ni/Fe      An r-process      Effects of 12C +12C   Neutron Stars and Black Holes:      Black Hole spectrum      Mass Gap with LVK      Compact object IMF      He burn neutron stars   Stars:      Hypatia catalog      SAGB stars      Nugrid Yields I      He shell convection      BBFH at 40 years      γ-rays within 100 Mpc      Iron Pseudocarbynes   Pre-Solar Grains:      C-rich presolar grains      SiC Type U/C grains      Grains from massive stars      Placing the Sun      SiC Presolar grains   Chemical Evolution:      Radionuclides in 2020s      Zone models H to Zn      Mixing ejecta   Thermodynamics, Opacities & Networks      Radiative Opacity      Skye EOS      Helm EOS      Five EOSs      Equations of State      12C(α,γ)16O Rate      Proton-rich NSE      Reaction networks      Bayesian reaction rates   Verification Problems:      Validating an astro code      Su-Olson      Cog8      Mader      RMTV      Sedov      Noh Software Instruments AAS Journals    2025 AAS YouTube    2025 AAS Peer Review Workshops 2025 ASU Energy in Everyday Life 2025 MESA Classroom Other Stuff:    Bicycle Adventures    Illustrations    Presentations Contact: F.X.Timmes my one page vitae, full vitae, research statement, and teaching statement.	31Mar2025 MESA moves to the Flatiron Institute! The happy announcement from the Simons Foundation. Modules for Experiments in Stellar Astrophysics: Time-Dependent Convection, Energy Conservation, Automatic Differentiation, and Infrastructure - MESA ⅤⅠ, 2023 In this article, we update the capabilities of the open-knowledge software instrument Modules for Experiments in Stellar Astrophysics (MESA). The new auto_diff module implements automatic differentiation in MESA, an enabling capability that alleviates the need for hard-coded analytic expressions or finite difference approximations. We significantly enhance the treatment of the growth and decay of convection in MESA with a new model for time-dependent convection, which is particularly important during late-stage nuclear burning in massive stars and electron degenerate ignition events. We strengthen MESA's implementation of the equation of state, and we quantify continued improvements to energy accounting and solver accuracy through a discussion of different energy equation features and enhancements. To improve the modeling of stars in MESA, we describe key updates to the treatment of stellar atmospheres, molecular opacities, Compton opacities, conductive opacities, element diffusion coefficients, and nuclear reaction rates. We introduce treatments of starspots, an important consideration for low-mass stars, and modifications for superadiabatic convection in radiation-dominated regions. We describe new approaches for increasing the efficiency of calculating monochromatic opacities and radiative levitation, and for increasing the efficiency of evolving the late stages of massive stars with a new operator split nuclear burning mode. We close by discussing major updates to MESA's software infrastructure that enhance source code development and community engagement. TDC schematic EOS regions Tests Submitted MESA appears in the Netflix movie "Don't Look Up" - 2022 First noted by Jared Goldberg on his Twitter feed, a lovely ApJ Supplement figure makes an appearance at about the 1 hr 11 min mark: Here is the relevant page in the movie's mashup "report": How and Why figure 4 of MESA III figure appears in the movie is a story itself. Thank you Amy Mainzer! Tinsley Prize - 2021 Bill Paxton was awarded the 2021 Beatrice M. Tinsley Prize "for his inspired work on providing, maintaining, and supporting the use of open-source stellar-evolution codes that have seeped into the foundation of research and education efforts and have given rise to an immense amount of new research across multiple subfields of astrophysics." The Tinsley Prize, awarded every two years by the American Astronomical Society, recognizes an outstanding research contribution to astronomy or astrophysics of an exceptionally creative or innovative character. Thank you Bill! Modules for Experiments in Stellar Astrophysics: Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation - MESA Ⅴ, 2019 In this paper, we update the capabilities of the open-knowledge software instrument Modules for Experiments in Stellar Astrophysics (MESA). RSP is a new functionality in MESAstar that models the nonlinear radial stellar pulsations that characterize RR Lyrae, Cepheids, and other classes of variable stars. We significantly enhance numerical energy conservation capabilities, including during mass changes. For example, this enables calculations through the He flash that conserve energy to better than 0.001%. To improve the modeling of rotating stars in MESA, we introduce a new approach to modifying the pressure and temperature equations of stellar structure, as well as a formulation of the projection effects of gravity darkening. A new scheme for tracking convective boundaries yields reliable values of the convective core mass and allows the natural emergence of adiabatic semiconvection regions during both core hydrogen- and helium-burning phases. We quantify the parallel performance of MESA on current-generation multicore architectures and demonstrate improvements in the computational efficiency of radiative levitation. We report updates to the equation of state and nuclear reaction physics modules. We briefly discuss the current treatment of fallback in core-collapse supernova models and the thermodynamic evolution of supernova explosions. We close by discussing the new MESA Testhub software infrastructure to enhance source code development. Nonlinear pulsations He flash and gold tolerances Equipotentials of Roche potential Grad profiles with CPM Modules for Experiments in Stellar Astrophysics: Convective Boundaries, Element Diffusion, and Massive Star Explosions - MESA Ⅳ, 2018 In this paper, we update the capabilities of the software instrument Modules for Experiments in Stellar Astrophysics (MESA) and enhance its ease of use and availability. Our new approach to locating convective boundaries is consistent with the physics of convection, and yields reliable values of the convective core mass during both hydrogen and helium burning phases. Stars with M < 8 Msun become white dwarfs and cool to the point where the electrons are degenerate and the ions are strongly coupled, a realm now available to study with MESA due to improved treatments of element diffusion, latent heat release, and blending of equations of state. Studies of the final fates of massive stars are extended in MESA by our addition of an approximate Riemann solver that captures shocks and conserves energy to high accuracy during dynamic epochs. We also introduce a 1D capability for modeling the effects of Rayleigh-Taylor instabilities that, in combination with the coupling to a public version of the STELLA radiation transfer instrument, creates new avenues for exploring Type II supernovae properties. These capabilities are exhibited with exploratory models of pair-instability supernova, pulsational pair-instability supernova, and the formation of stellar mass black holes. The applicability of MESA is now widened by the capability of importing multi-dimensional hydrodynamic models into MESA. We close by introducing software modules for handling floating point exceptions and stellar model optimization, and four new software tools - MESA-Web, MESA-Docker, pyMESA, and mesastar.org - to enhance MESA's education and research impact. Sedov Entropy Trail H shell flash on He WD Modules for Experiments in Stellar Astrophysics: Binaries, Pulsations, and Explosions - MESA Ⅲ, 2015 In this paper, we substantially update the capabilities of the open-source software instrument Modules for Experiments in Stellar Astrophysics (MESA). MESA can now simultaneously evolve an interacting pair of differentially rotating stars undergoing transfer and loss of mass and angular momentum, greatly enhancing the prior ability to model binary evolution. New MESA capabilities in fully coupled calculation of nuclear networks with hundreds of isotopes now allow MESA to accurately simulate advanced burning stages needed to construct supernova progenitor models. Implicit hydrodynamics with shocks can now be treated with MESA, enabling modeling of the entire massive star lifecycle, from pre-main sequence evolution to the onset of core collapse and nucleosynthesis from the resulting explosion. Coupling of the GYRE non-adiabatic pulsation instrument with MESA allows for new explorations of the instability strips for massive stars while also accelerating the astrophysical use of asteroseismology data. We improve treatment of mass accretion, giving more accurate and robust near-surface profiles. A new MESA capability to calculate weak reaction rates "on-the-fly" from input nuclear data allows better simulation of accretion induced collapse of massive white dwarfs and the fate of some massive stars. We discuss the ongoing challenge of chemical diffusion in the strongly coupled plasma regime, and exhibit improvements in MESA that now allow for the simulation of radiative levitation of heavy elements in hot stars. We close by noting that the MESA software infrastructure provides bit-for-bit consistency for all results across all the supported platforms, a profound enabling capability for accelerating MESA's development. 16 M☉ + 14 M☉ binary Instability strips 1.57×1051 erg explosion Modules for Experiments in Stellar Astrophysics: Giant Planets, Oscillations, Rotation, and Massive Stars - MESA Ⅱ, 2013 In this paper, we substantially update the capabilities of the open source software package Modules for Experiments in Stellar Astrophysics (MESA), and its one-dimensional stellar evolution module, MESAstar. Improvements in MESAstar's ability to model the evolution of giant planets now extends its applicability down to masses as low as one-tenth that of Jupiter. The dramatic improvement in asteroseismology enabled by the space-based Kepler and CoRoT missions motivates our full coupling of the ADIPLS adiabatic pulsation code with MESAstar. This also motivates a numerical recasting of the Ledoux criterion that is more easily implemented when many nuclei are present at non-negligible abundances. This impacts the way in which MESAstar calculates semi-convective and thermohaline mixing. We exhibit the evolution of 3-8 Msun stars through the end of core He burning, the onset of He thermal pulses, and arrival on the white dwarf cooling sequence. We implement diffusion of angular momentum and chemical abundances that enable calculations of rotating-star models, which we compare thoroughly with earlier work. We introduce a new treatment of radiation-dominated envelopes that allows the uninterrupted evolution of massive stars to core collapse. This enables the generation of new sets of supernovae, long gamma-ray burst, and pair-instability progenitor models. We substantially modify the way in which MESAstar solves the fully coupled stellar structure and composition equations, and we show how this has improved MESA's performance scaling on multi-core processors. Updates to the modules for equation of state, opacity, nuclear reaction rates, and atmospheric boundary conditions are also provided. We describe the MESA Software Development Kit (SDK) that packages all the required components needed to form a unified and maintained build environment for MESA. Giant planet evolution Echelle diagram of HD43985. Magnetic field and angular momentum Modules For Experiments In Stellar Astrophysics - MESA Ⅰ, 2011 In this paper, we describe Modules for Experiments in Stellar Astrophysics (MESA), 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. MESA can be downloaded from the project Web site https://docs.mesastar.org Equation of State Opacity Massive stars in ρ-T plane MESA Summer Schools Title What, When, and Where ☆ MESA Marketplace Aggregator site ☆ 2025 MESA Summer School 21Jul- 25Jul, Leuven ☆ 2024 MESA Down Under 17Jun - 21Jun, Sydney ☆ 2023 MESA Summer School 28Aug - 01Sep, Konkoly ☆ 2022 MESA Summer School Aug 8-12, 2022, UCSB ☆ 2021 MESA Summer School Aug 9-20, 2021, Online ☆ 2020 MESA Summer School Aug 10-14, 2020, Cancelled ☆ 2019 MESA Summer School Aug 12-16, 2019, UCSB ☆ 2018 MESA Summer School Aug 13-17, 2018, UCSB ☆ Simulating Stars: From Theory to Observations June 25-29, 2018, Beijing ☆ 2017 MESA Summer School Aug 14-18, 2017, UCSB ☆ 2016 MESA Summer School Aug 15-19, 2016, UCSB ☆ 2015 MESA Summer School Aug 10-14, 2015, UCSB ☆ 2014 MESA Summer School Aug 11-15, 2014, UCSB ☆ 2013 MESA Summer School Aug 12-16, 2013, UCSB ☆ 2012 MESA Summer School Aug 13-17, 2012, UCSB