Stellar Evolution and Convection in 3D Hydrodynamic Simulations of a Complete Burning Phase (2024)
Journal Article
Rizzuti, F., Hirschi, R., Varma, V., Arnett, W. D., Georgy, C., Meakin, C., Mocák, M., Murphy, A. S., & Rauscher, T. (2024). Stellar Evolution and Convection in 3D Hydrodynamic Simulations of a Complete Burning Phase. Galaxies, 12(6), 87. https://doi.org/10.3390/galaxies12060087

Our understanding of stellar evolution and nucleosynthesis is limited by the uncertainties coming from the complex multi-dimensional processes in stellar interiors, such as convection and nuclear burning. Three-dimensional stellar models can improve... Read More about Stellar Evolution and Convection in 3D Hydrodynamic Simulations of a Complete Burning Phase.

3D stellar evolution: hydrodynamic simulations of a complete burning phase in a massive star (2023)
Journal Article
Rizzuti, F., Hirschi, R., Arnett, W. D., Georgy, C., Meakin, C., Murphy, A. S., Rauscher, T., & Varma, V. (2023). 3D stellar evolution: hydrodynamic simulations of a complete burning phase in a massive star. Monthly Notices of the Royal Astronomical Society, 523(2), 2317-2328. https://doi.org/10.1093/mnras/stad1572

Our knowledge of stellar evolution is driven by one-dimensional (1D) simulations. 1D models, however, are severely limited by uncertainties on the exact behaviour of many multidimensional phenomena occurring inside stars, affecting their structure an... Read More about 3D stellar evolution: hydrodynamic simulations of a complete burning phase in a massive star.

The effects of surface fossil magnetic fields on massive star evolution: IV. Grids of models at Solar, LMC, and SMC metallicities (2022)
Journal Article
Keszthelyi, Z., de Koter, A., Götberg, Y., Meynet, G., Brands, S. A., Petit, V., Carrington, M., David-Uraz, A., Geen, S. T., Georgy, C., Hirschi, R., Puls, J., Ramalatswa, K. J., Shultz, M. E., & ud-Doula, A. (2022). The effects of surface fossil magnetic fields on massive star evolution: IV. Grids of models at Solar, LMC, and SMC metallicities. Monthly Notices of the Royal Astronomical Society, 517(2), 2028 - 2055. https://doi.org/10.1093/mnras/stac2598

Magnetic fields can drastically change predictions of evolutionary models of massive stars via mass-loss quenching, magnetic braking, and efficient angular momentum transport, which we aim to quantify in this work. We use the MESA software instrument... Read More about The effects of surface fossil magnetic fields on massive star evolution: IV. Grids of models at Solar, LMC, and SMC metallicities.

Very massive star winds as sources of the short-lived radioactive isotope Al-26 (2022)
Journal Article
Hirschi. (2022). Very massive star winds as sources of the short-lived radioactive isotope Al-26. Astronomy & Astrophysics,

Context. The 26Al short-lived radioactive nuclide is the source of the observed galactic diffuse ?-ray emission at 1.8 MeV. While different sources of 26Al have been explored, such as asymptotic giant branch stars, massive stellar winds, and supernov... Read More about Very massive star winds as sources of the short-lived radioactive isotope Al-26.

The impact of O-17 + alpha reaction rate uncertainties on the s-process in rotating massive stars (2022)
Journal Article
Frost-Schenk, J., Adsley, P., Laird, A. M., Longland, R., Angus, C., Barton, C., Choplin, A., Aa Diget, C., Hirschi, R., Marshall, C., Portillo Chaves, F., & Setoodehnia, K. (2022). The impact of O-17 + alpha reaction rate uncertainties on the s-process in rotating massive stars. Monthly Notices of the Royal Astronomical Society, 514(2), 2650 - 2657. https://doi.org/10.1093/mnras/stac1373

Massive stars are crucial to galactic chemical evolution for elements heavier than iron. Their contribution at early times in the evolution of the Universe, however, is unclear due to poorly constrained nuclear reaction rates. The competing 17O(a, ?)... Read More about The impact of O-17 + alpha reaction rate uncertainties on the s-process in rotating massive stars.

The p-process in exploding rotating massive stars (2022)
Journal Article
Choplin, A., Goriely, S., Hirschi, R., Tominaga, N., & Meynet, G. (2022). The p-process in exploding rotating massive stars. Astronomy & Astrophysics, 661, Article A86. https://doi.org/10.1051/0004-6361/202243331

Context. The p-process nucleosynthesis can explain proton-rich isotopes that are heavier than iron, which are observed in the Solar System, but discrepancies still persist (e.g. for the Mo and Ru p-isotopes), and some important questions concerning t... Read More about The p-process in exploding rotating massive stars.

Grids of stellar models with rotation VII: models from 0.8 to 300 M-circle dot at supersolar metallicity (Z=0.020) (2022)
Journal Article
Yusof, N., Hirschi, R., Eggenberger, P., Ekström, S., Georgy, C., Sibony, Y., Crowther, P. A., Meynet, G., Abu Kassim, H., Aishah Wan Harun, W., Maeder, A., Groh, J. H., Farrell, E., & Murphy, L. (2022). Grids of stellar models with rotation VII: models from 0.8 to 300 M-circle dot at supersolar metallicity (Z=0.020). Monthly Notices of the Royal Astronomical Society, 511(2), 2814 - 2828. https://doi.org/10.1093/mnras/stac230

We present a grid of stellar models at supersolar metallicity (Z = 0.020) extending the previous grids of Geneva models at solar and sub-solar metallicities. A metallicity of Z = 0.020 was chosen to match that of the inner Galactic disc. A modest inc... Read More about Grids of stellar models with rotation VII: models from 0.8 to 300 M-circle dot at supersolar metallicity (Z=0.020).

UVES analysis of red giants in the bulge globular cluster NGC 6522 (2021)
Journal Article
Hirschi. (2021). UVES analysis of red giants in the bulge globular cluster NGC 6522. Astronomy & Astrophysics, https://doi.org/10.1051/0004-6361/202140815

Context. NGC 6522 is a moderately metal-poor bulge globular cluster ([Fe/H] ~ -1.0), and it is a well-studied representative among a number of moderately metal-poor blue horizontal branch clusters located in the bulge. The NGC 6522 abundance pattern... Read More about UVES analysis of red giants in the bulge globular cluster NGC 6522.

Multidimensional low-Mach number time-implicit hydrodynamic simulations of convective helium shell burning in a massive star (2021)
Journal Article
Hirschi. (2021). Multidimensional low-Mach number time-implicit hydrodynamic simulations of convective helium shell burning in a massive star. Astronomy & Astrophysics, 1-24. https://doi.org/10.1051/0004-6361/202140825

Context. A realistic parametrization of convection and convective boundary mixing in conventional stellar evolution codes is still the subject of ongoing research. To improve the current situation, multidimensional hydrodynamic simulations are used t... Read More about Multidimensional low-Mach number time-implicit hydrodynamic simulations of convective helium shell burning in a massive star.

Grids of stellar models with rotation VI. Models from 0.8 to 120 M-circle dot at a metallicity Z=0.006 (2021)
Journal Article
Hirschi. (2021). Grids of stellar models with rotation VI. Models from 0.8 to 120 M-circle dot at a metallicity Z=0.006. Astronomy & Astrophysics,

Context. Grids of stellar models, computed with the same physical ingredients, allow one to study the impact of a given physics on a broad range of initial conditions and they are a key ingredient for modeling the evolution of galaxies.

Aims. We p... Read More about Grids of stellar models with rotation VI. Models from 0.8 to 120 M-circle dot at a metallicity Z=0.006.

Evolution of Wolf-Rayet stars as black hole progenitors (2021)
Journal Article
Higgins, E. R., Sander, A. A. C., Vink, J. S., & Hirschi, R. (2021). Evolution of Wolf-Rayet stars as black hole progenitors. Monthly Notices of the Royal Astronomical Society, 505(4), 4874-4889. https://doi.org/10.1093/mnras/stab1548

Evolved Wolf-Rayet stars form a key aspect of massive star evolution, and their strong outflows determine their final fates. In this study, we calculate grids of stellar models for a wide range of initial masses at five metallicities (ranging from so... Read More about Evolution of Wolf-Rayet stars as black hole progenitors.

Convective core sizes in rotating massive stars: I. Constraints from solar metallicity OB field stars (2021)
Journal Article
Martinet, S., Meynet, G., Ekström, S., Simón-Díaz, S., Holgado, G., Castro, N., Georgy, C., Eggenberger, P., Buldgen, G., Salmon, S., Hirschi, R., Groh, J., Farrell, E., & Murphy, L. (2021). Convective core sizes in rotating massive stars: I. Constraints from solar metallicity OB field stars. Astronomy & Astrophysics, 648, Article A126. https://doi.org/10.1051/0004-6361/202039426

Context. Spectroscopic studies of Galactic O and B stars show that many stars with masses above 8 M? have been observed in the Hertzsprung-Russell (HR) diagram just beyond the main-sequence (MS) band, as predicted by stellar models computed with a mo... Read More about Convective core sizes in rotating massive stars: I. Constraints from solar metallicity OB field stars.

Convective core entrainment in 1D main-sequence stellar models (2021)
Journal Article
Scott, L. J. A., Hirschi, R., Georgy, C., Arnett, W. D., Meakin, C., Kaiser, E. A., Ekström, S., & Yusof, N. (2021). Convective core entrainment in 1D main-sequence stellar models. Monthly Notices of the Royal Astronomical Society, 503(3), 4208 - 4220. https://doi.org/10.1093/mnras/stab752

3D hydrodynamics models of deep stellar convection exhibit turbulent entrainment at the convective-radiative boundary which follows the entrainment law, varying with boundary penetrability. We implement the entrainment law in the 1D Geneva stellar ev... Read More about Convective core entrainment in 1D main-sequence stellar models.

Constraints on stellar rotation from the evolution of Sr and Ba in the Galactic halo (2021)
Journal Article
Rizzuti, F., Cescutti, G., Matteucci, F., Chieffi, A., Hirschi, R., Limongi, M., & Saro, A. (2021). Constraints on stellar rotation from the evolution of Sr and Ba in the Galactic halo. Monthly Notices of the Royal Astronomical Society, 502(2), 2495-2507. https://doi.org/10.1093/mnras/stab158

Recent studies show that the chemical evolution of Sr and Ba in the Galaxy can be explained if different production sites, hosting r- and s-processes, are taken into account. However, the question of unambiguously identifying these sites is still uns... Read More about Constraints on stellar rotation from the evolution of Sr and Ba in the Galactic halo.

Is GW190521 the merger of black holes from the first stellar generations? (2020)
Journal Article
Farrell, E., Groh, J. H., Hirschi, R., Murphy, L., Kaiser, E., Ekström, S., Georgy, C., & Meynet, G. (2021). Is GW190521 the merger of black holes from the first stellar generations?. Monthly Notices of the Royal Astronomical Society, 502(1), L40-L44. https://doi.org/10.1093/mnrasl/slaa196

GW190521 challenges our understanding of the late-stage evolution of massive stars and the effects of the pair-instability in particular. We discuss the possibility that stars at low or zero metallicity could retain most of their hydrogen envelope un... Read More about Is GW190521 the merger of black holes from the first stellar generations?.

Grids of stellar models with rotation: V. Models from 1.7 to 120 Msun at zero metallicity (2020)
Journal Article
Murphy, L. J., Groh, J. H., Ekström, S., Meynet, G., Pezzotti, C., Georgy, C., Choplin, A., Eggenberger, P., Farrell, E., Haemmerlé, L., Hirschi, R., Maeder, A., & Martinet, S. (2021). Grids of stellar models with rotation: V. Models from 1.7 to 120 Msun at zero metallicity. Monthly Notices of the Royal Astronomical Society, 501(2), 2745-2763. https://doi.org/10.1093/mnras/staa3803

Understanding the nature of the first stars is key to understanding the early universe. With new facilities such as JWST we may soon have the first observations of the earliest stellar populations, but to understand these observations we require deta... Read More about Grids of stellar models with rotation: V. Models from 1.7 to 120 Msun at zero metallicity.

Relative Importance of Convective Uncertainties in Massive Stars (2020)
Journal Article
Kaiser, E. A., Hirschi, R., Arnett, W. D., Georgy, C., Scott, L. J. A., & Cristini, A. (2020). Relative Importance of Convective Uncertainties in Massive Stars. Monthly Notices of the Royal Astronomical Society, 496(2), 1967-1989. https://doi.org/10.1093/mnras/staa1595

In this work, we investigate the impact of uncertainties due to convective boundary mixing (CBM), commonly called ‘overshoot’, namely the boundary location and the amount of mixing at the convective boundary, on stellar structure and evolution. For t... Read More about Relative Importance of Convective Uncertainties in Massive Stars.

Evolutionary roads leading to low effective spins, high black hole masses, and O1/O2 rates for LIGO/Virgo binary black holes (2020)
Journal Article
Belczynski, K., Klencki, J., Fields, C., Olejak, A., Berti, E., Meynet, G., Fryer, C., Holz, D., O’Shaughnessy, R., Brown, D., Bulik, T., Leung, S., Nomoto, K., Madau, P., Hirschi, R., Kaiser, E., Jones, S., Mondal, S., Chruslinska, M., Drozda, P., …Lasota, J.-P. (2020). Evolutionary roads leading to low effective spins, high black hole masses, and O1/O2 rates for LIGO/Virgo binary black holes. Astronomy and Astrophysics, 636, Article A104. https://doi.org/10.1051/0004-6361/201936528

All ten LIGO/Virgo binary black hole (BH-BH) coalescences reported following the O1/O2 runs have near-zero effective spins. There are only three potential explanations for this. If the BH spin magnitudes are large, then: (i) either both BH spin vecto... Read More about Evolutionary roads leading to low effective spins, high black hole masses, and O1/O2 rates for LIGO/Virgo binary black holes.

The Formation of a 70 M ? Black Hole at High Metallicity (2020)
Journal Article
Hirschi. (2020). The Formation of a 70 M ? Black Hole at High Metallicity. Astrophysical Journal, 113 -113. https://doi.org/10.3847/1538-4357/ab6d77

A 70 black hole (BH) was discovered in the Milky Way disk in a long-period detached binary system (LB-1) with a high-metallicity 8 B star companion. Current consensus on the formation of BHs from high-metallicity stars limits the BH mass to be below... Read More about The Formation of a 70 M ? Black Hole at High Metallicity.

The s process in rotating low-mass AGB stars - Nucleosynthesis calculations in models matching asteroseismic constraints (2019)
Journal Article
Hirschi. (2019). The s process in rotating low-mass AGB stars - Nucleosynthesis calculations in models matching asteroseismic constraints. Astronomy and Astrophysics, A123 -A123. https://doi.org/10.1051/0004-6361/201935476

Aims
We investigate the s-process during the AGB phase of stellar models whose cores are enforced to rotate at rates consistent with asteroseismology observations of their progenitors and successors.

Methods
We calculated new 2 M?, Z = 0.01 mode... Read More about The s process in rotating low-mass AGB stars - Nucleosynthesis calculations in models matching asteroseismic constraints.