Outputs (130)

Very massive star models: I. Impact of rotation and metallicity and comparisons with observations (2023)
Journal Article
Martinet, S., Meynet, G., Ekström, S., Georgy, C., & Hirschi, R. (2023). Very massive star models: I. Impact of rotation and metallicity and comparisons with observations. Astronomy & Astrophysics, 679, Article A137. https://doi.org/10.1051/0004-6361/202347514

Context. In addition to being spectacular objects, very massive stars (VMSs) are suspected to have a tremendous impact on their environment and on cosmic evolution in general. The nucleosynthesis both during their advanced stages and their final expl... Read More about Very massive star models: I. Impact of rotation and metallicity and comparisons with observations.

The Nuclear Reaction Network WinNet (2023)
Journal Article
Reichert, M., Winteler, C., Korobkin, O., Arcones, A., Bliss, J., Eichler, M., …Thielemann, F. (2023). The Nuclear Reaction Network WinNet. The Astrophysical Journal Supplement, 268(2), Article 66. https://doi.org/10.3847/1538-4365/acf033

We present the state-of-the-art single-zone nuclear reaction network WinNet, which is capable of calculating the nucleosynthetic yields of a large variety of astrophysical environments and conditions. This ranges from the calculation of the primordia... Read More about The Nuclear Reaction Network WinNet.

Slow Neutron-Capture Process in Evolved Stars (2023)
Book Chapter
Hirschi, R. (2023). Slow Neutron-Capture Process in Evolved Stars. In Handbook of Nuclear Physics (3537-3571). Springer. https://doi.org/10.1007/978-981-19-6345-2_118

The slow neutron-capture process (s process) contributes to the production of roughly half of the elements heavier than iron. The main component of the s process takes place in the late phases (AGB phase) of low-mass stars and is the topic of most re... Read More about Slow Neutron-Capture Process in Evolved Stars.

Stellar wind yields of very massive stars (2023)
Journal Article
Higgins, E. R., Vink, J. S., Hirschi, R., Laird, A. M., & Sabhahit, G. N. (in press). Stellar wind yields of very massive stars. Monthly Notices of the Royal Astronomical Society, 526(1), 534–547. https://doi.org/10.1093/mnras/stad2537

The most massive stars provide an essential source of recycled material for young clusters and galaxies. While very massive stars (VMS, M>100 $\rm {\rm M}_{\odot }$) are relatively rare compared to O stars, they lose disproportionately large a... Read More about Stellar wind yields of very massive stars.

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., …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.

Turbulence and nuclear reactions in 3D hydrodynamics simulations of massive stars (2023)
Journal Article
Rizzuti, F., Hirschi, R., Georgy, C., Arnett, D., Meakin, C., & Murphy, A. (2023). Turbulence and nuclear reactions in 3D hydrodynamics simulations of massive stars. EPJ Web of Conferences, 279, 05001. https://doi.org/10.1051/epjconf/202327905001

Our knowledge of massive star evolution and nucleosynthesis is limited by uncertainties related to multi-dimensional processes taking place in stellar interiors. Recently, theoretical works have started to improve 1D stellar evolution codes through t... Read More about Turbulence and nuclear reactions in 3D hydrodynamics simulations of massive stars.

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., …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.

Very massive star winds as sources of the short-lived radioactive isotope 26Al (2022)
Journal Article
Martinet, S., Meynet, G., Nandal, D., Ekström, S., Georgy, C., Haemmerlé, L., …Dwarkadas, V. (2022). Very massive star winds as sources of the short-lived radioactive isotope 26Al. Astronomy & Astrophysics, 664, A181. https://doi.org/10.1051/0004-6361/202243474

Context. The 26Al short-lived radioactive nuclide is the source of the observed galactic diffuse γ-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 26Al.

Realistic 3D hydrodynamics simulations find significant turbulent entrainment in massive stars (2022)
Journal Article
Rizzuti, F., Hirschi, R., Georgy, C., Arnett, W. D., Meakin, C., & Murphy, A. S. (2022). Realistic 3D hydrodynamics simulations find significant turbulent entrainment in massive stars. Monthly Notices of the Royal Astronomical Society, 515(3), 4013-4019. https://doi.org/10.1093/mnras/stac1981

Our understanding of stellar structure and evolution coming from one-dimensional (1D) stellar models is limited by uncertainties related to multidimensional processes taking place in stellar interiors. 1D models, however, can now be tested and improv... Read More about Realistic 3D hydrodynamics simulations find significant turbulent entrainment in massive stars.

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., …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.

Dynamics in a stellar convective layer and at its boundary: Comparison of five 3D hydrodynamics codes (2022)
Journal Article
Andrassy, R., Higl, J., Mao, H., Mocak, M., Vlaykov, D. G., Arnett, W. D., …Woodward, P. (2022). Dynamics in a stellar convective layer and at its boundary: Comparison of five 3D hydrodynamics codes. Astronomy & Astrophysics, 659, Article ARTN A193. https://doi.org/10.1051/0004-6361/202142557

Our ability to predict the structure and evolution of stars is in part limited by complex, 3D hydrodynamic processes such as convective boundary mixing. Hydrodynamic simulations help us understand the dynamics of stellar convection and convective bou... Read More about Dynamics in a stellar convective layer and at its boundary: Comparison of five 3D hydrodynamics codes.

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., …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.

Grids of stellar models with rotation: VI. Models from 0.8 to 120 M⊙ at a metallicity Z = 0.006 (2021)
Journal Article
Eggenberger, P., Ekström, S., Georgy, C., Martinet, S., Pezzotti, C., Nandal, D., …Choplin, A. (2021). Grids of stellar models with rotation: VI. Models from 0.8 to 120 M⊙ at a metallicity Z = 0.006. Astronomy & Astrophysics, 652, Article A137. https://doi.org/10.1051/0004-6361/202141222

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⊙ 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., …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., …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.

Reevaluation of the Ne-23(alpha, gamma)Mg-26 and Ne-22(alpha, n)Mg-25 reaction (2021)
Journal Article
Adsley, P., Battino, U., Best, A., Caciolli, A., Guglielmetti, A., Imbriani, G., …Hirschi, R. (2021). Reevaluation of the Ne-23(alpha, gamma)Mg-26 and Ne-22(alpha, n)Mg-25 reaction. Physical Review C, 103(1), https://doi.org/10.1103/PhysRevC.103.015805

Background: The competing 22Ne(a,?)26Mg and 22Ne(a,n)25Mg reactions control the production of neutrons for the weak s process in massive and asymptotic giant branch (AGB) stars. In both systems, the ratio between the corresponding reaction rates stro... Read More about Reevaluation of the Ne-23(alpha, gamma)Mg-26 and Ne-22(alpha, n)Mg-25 reaction.

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., …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., …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.

Nucleosynthesis in early rotating massive stars and chemical composition of CEMP stars (2020)
Journal Article
Choplin, A., & Hirschi, R. (2020). Nucleosynthesis in early rotating massive stars and chemical composition of CEMP stars. Journal of Physics: Conference Series, 1668(1), Article 012006. https://doi.org/10.1088/1742-6596/1668/1/012006

The first massive stars triggered the onset of chemical evolution by releasing the first metals (elements heavier than helium) in the Universe. The nature of these stars and how the early chemical enrichment took place is still largely unknown. Rotat... Read More about Nucleosynthesis in early rotating massive stars and chemical composition of CEMP stars.

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., …Lasota, J. (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.

The contribution from rotating massive stars to the enrichment in Sr and Ba of the Milky Way (2019)
Journal Article
Rizzuti, F., Cescutti, G., Matteucci, F., Chieffi, A., Hirschi, R., & Limongi, M. (2019). The contribution from rotating massive stars to the enrichment in Sr and Ba of the Milky Way. Monthly Notices of the Royal Astronomical Society, 489(4), 5244 -5255. https://doi.org/10.1093/mnras/stz2505

Most neutron capture elements have a double production by r- and s-processes, but the question of production sites is complex and still open. Recent studies show that including stellar rotation can have a deep impact on nucleosynthesis. We studied th... Read More about The contribution from rotating massive stars to the enrichment in Sr and Ba of the Milky Way.

A direct measurement of the 17O(a,?)21Ne reaction in inverse kinematics and its impact on heavy element production (2019)
Journal Article
Taggart, M., Akers, C., Laird, A., Hager, U., Ruiz, C., Hutcheon, D., …Williams, M. (2019). A direct measurement of the 17O(a,?)21Ne reaction in inverse kinematics and its impact on heavy element production. Physics Letters B, 798(10), Article 134894. https://doi.org/10.1016/j.physletb.2019.134894

During the slow neutron capture process in massive stars, reactions on light elements can both produce and absorb neutrons thereby influencing the final heavy element abundances. At low metallicities, the high neutron capture rate of 16O can inhibit... Read More about A direct measurement of the 17O(a,?)21Ne reaction in inverse kinematics and its impact on heavy element production.

3D Simulations and MLT. I. Renzini’s Critique (2019)
Journal Article
Arnett, W. D., Meakin, C., Hirschi, R., Cristini, A., Georgy, C., Campbell, S., …Mocák, M. (2019). 3D Simulations and MLT. I. Renzini’s Critique. Astrophysical Journal, 882(1), 18. https://doi.org/10.3847/1538-4357/ab21d9

Renzini wrote an influential critique of “overshooting” in mixing-length theory (MLT), as used in stellar evolution codes, and concluded that three-dimensional fluid dynamical simulations were needed. Such simulations are now well tested. Implicit la... Read More about 3D Simulations and MLT. I. Renzini’s Critique.

NuGrid stellar data set – III. Updated low-mass AGB models and s-process nucleosynthesis with metallicities Z= 0.01, Z = 0.02, and Z = 0.03 (2019)
Journal Article
Battino, U., Tattersall, A., Lederer-Woods, C., Herwig, F., Denissenkov, P., Hirschi, R., …Collaboration, T. N. (2019). NuGrid stellar data set – III. Updated low-mass AGB models and s-process nucleosynthesis with metallicities Z= 0.01, Z = 0.02, and Z = 0.03. Monthly Notices of the Royal Astronomical Society, 489(1), 1082 -1098. https://doi.org/10.1093/mnras/stz2158

The production of the neutron-capture isotopes beyond iron that we observe today in the Solar system is the result of the combined contribution of the r-process, the s-process, and possibly the i-process. Low-mass asymptotic giant branch (AGB) (1.5 &... Read More about NuGrid stellar data set – III. Updated low-mass AGB models and s-process nucleosynthesis with metallicities Z= 0.01, Z = 0.02, and Z = 0.03.

Relative Importance of Convective Uncertainties (2019)
Conference Proceeding
Kaiser, E. A., Hirschi, R., Arnett, W. D., Cristini, A., Georgy, C., & Scott, L. J. A. (2019). Relative Importance of Convective Uncertainties. . https://doi.org/10.1007/978-3-030-13876-9_71

Convection plays a key role in the evolution of stars due to energy transport and mixing of composition. Despite its importance, this process is still not well understood. One longstanding conundrum in all 1D stellar evolution codes is the treatment... Read More about Relative Importance of Convective Uncertainties.

Uncertainties in νp-process nucleosynthesis from Monte Carlo variation of reaction rates (2019)
Journal Article
Nishimura (西村信哉), N., Rauscher, T., Hirschi, R., Hirschi, R., Cescutti, G., Murphy, A. S. J., & Fröhlich, C. (2019). Uncertainties in νp-process nucleosynthesis from Monte Carlo variation of reaction rates. Monthly Notices of the Royal Astronomical Society, 489(1), 1379-1396. https://doi.org/10.1093/mnras/stz2104

It has been suggested that a ?p process can occur when hot, dense, and proton-rich matter is expanding within a strong flux of anti-neutrinos. In such an environment, proton-rich nuclides can be produced in sequences of proton captures and (n, p) rea... Read More about Uncertainties in νp-process nucleosynthesis from Monte Carlo variation of reaction rates.

Grids of stellar models with rotation IV. Models from 1.7 to 120 M-circle dot at a metallicity Z=0.0004 (2019)
Journal Article
Groh, J., Ekström, S., Georgy, C., Meynet, G., Choplin, A., Eggenberger, P., …Farrell, E. (2019). Grids of stellar models with rotation IV. Models from 1.7 to 120 M-circle dot at a metallicity Z=0.0004. Astronomy & Astrophysics, 627, Article A24. https://doi.org/10.1051/0004-6361/201833720

The effects of rotation on stellar evolution are particularly important at low metallicity, when mass loss by stellar winds diminishes and the surface enrichment due to rotational mixing becomes relatively more pronounced than at high metallicities.... Read More about Grids of stellar models with rotation IV. Models from 1.7 to 120 M-circle dot at a metallicity Z=0.0004.

Constraining transport of angular momentum in stars Combining asteroseismic observations of core helium burning stars and white dwarfs (2019)
Journal Article
den Hartogh, J., Eggenberger, P., & Hirschi, R. (2019). Constraining transport of angular momentum in stars Combining asteroseismic observations of core helium burning stars and white dwarfs. Astronomy & Astrophysics, 622, 1-10. https://doi.org/10.1051/0004-6361/201834330

Context Transport of angular momentum has been a challenging topic within the stellar evolution community, even more since the recent asteroseismic surveys. All published studies on rotation using asteroseismic observations show a discrepancy betwee... Read More about Constraining transport of angular momentum in stars Combining asteroseismic observations of core helium burning stars and white dwarfs.

Dependence of convective boundary mixing on boundary properties and turbulence strength (2019)
Journal Article
Cristini, A., Hirschi, R., Meakin, C., Arnett, D., Georgy, C., & Walkington, I. (2019). Dependence of convective boundary mixing on boundary properties and turbulence strength. Monthly Notices of the Royal Astronomical Society, 484(4), 4645 - 4664. https://doi.org/10.1093/mnras/stz312

Convective boundary mixing is one of the major uncertainties in stellar evolution. In order to study its dependence on boundary properties and turbulence strength in a controlled way, we computed a series of 3D hydrodynamical simulations of stellar c... Read More about Dependence of convective boundary mixing on boundary properties and turbulence strength.

Non-standard s-process in massive rotating stars (2018)
Journal Article
Hirschi, R. (2018). Non-standard s-process in massive rotating stars. Astronomy and Astrophysics, https://doi.org/10.1051/0004-6361/201833283

Context Recent studies show that rotation significantly affects the s-process in massive stars. Aims We provide tables of yields for non-rotating and rotating massive stars between 10 and 150 M? at Z = 10-3 ([Fe/H] = -1.8). Tables for different... Read More about Non-standard s-process in massive rotating stars.

3D Simulations and MLT: II. Onsager's Ideal Turbulence (2018)
Journal Article
Arnett, W. D., Hirschi, R., Campbell, S. W., Mocák, M., Georgy, C., Meakin, C., …Viallet, M. (2018). 3D Simulations and MLT: II. Onsager's Ideal Turbulence. arXiv, https://doi.org/10.48550/arXiv.1810.04659

NuGrid Stellar Data Set. II. Stellar Yields from H to Bi for Stellar Models with MZAMS = 1 to 25 M? and Z = 0.0001 to 0.02 (2018)
Journal Article
Ritter, C., Herwig, F., Jones, S., Pignatari, M., Fryer, C., & Hirschi, R. (2018). NuGrid Stellar Data Set. II. Stellar Yields from H to Bi for Stellar Models with MZAMS = 1 to 25 M? and Z = 0.0001 to 0.02. Monthly Notices of the Royal Astronomical Society, 480(1), 538-571. https://doi.org/10.1093/mnras/sty1729

We provide here a significant extension of the NuGrid Set 1 models in mass coverage and toward lower metallicity, adopting the same physics assumptions. The combined data set now includes the initial masses MZAMS/?M? = 1, 1.65, 2, 3, 4, 5, 6, 7, 12,... Read More about NuGrid Stellar Data Set. II. Stellar Yields from H to Bi for Stellar Models with MZAMS = 1 to 25 M? and Z = 0.0001 to 0.02.

OGLE14-073 – a promising pair-instability supernova candidate (2018)
Journal Article
Kozyreva, A., Kromer, M., Noebauer, U. M., & Hirschi, R. (2018). OGLE14-073 – a promising pair-instability supernova candidate. Monthly Notices of the Royal Astronomical Society, 479(3), 3106 - 3114. https://doi.org/10.1093/mnras/sty983

The recently discovered bright Type? II supernova OGLE14-073 evolved very slowly. The light curve rose to maximum for 90?d from discovery and then declined at a rate compatible with the radioactive decay of 56Co. In this study, we show that a pair-in... Read More about OGLE14-073 – a promising pair-instability supernova candidate.

Uncertainties in s -process nucleosynthesis in low mass stars determined from Monte Carlo variations (2018)
Journal Article
Cescutti, G., Hirschi, R., Nishimura, N., den Hartogh, J. W., Rauscher, T., Murphy, A. S. J., & Cristallo, S. (2018). Uncertainties in s -process nucleosynthesis in low mass stars determined from Monte Carlo variations. Monthly Notices of the Royal Astronomical Society, 478(3), 4101-4127. https://doi.org/10.1093/mnras/sty1185

The main s-process taking place in low mass stars produces about half of the elements heavier than iron. It is therefore very important to determine the importance and impact of nuclear physics uncertainties on this process. We have performed extensi... Read More about Uncertainties in s -process nucleosynthesis in low mass stars determined from Monte Carlo variations.

Abundance uncertainties obtained with the PIZBUIN framework for Monte Carlo reaction rate variations (2018)
Journal Article
Rauscher, T., Nishimura, N., Cescutti, G., Hirschi, R., & Murphy, A. S. J. (2018). Abundance uncertainties obtained with the PIZBUIN framework for Monte Carlo reaction rate variations. AIP conference proceedings, 1947(1), https://doi.org/10.1063/1.5030819

Uncertainties in nucleosynthesis models originating from uncertainties in astrophysical reaction rates were estimated in a Monte Carlo variation procedure. Thousands of rates were simultaneously varied within individual, temperature-dependent errors... Read More about Abundance uncertainties obtained with the PIZBUIN framework for Monte Carlo reaction rate variations.

Impact of rotation and magnetic fields in low mass AGB stars (2018)
Conference Proceeding
den Hartogh, J. W., Hirschi, R., Georgy, C., Eggenberger, P., Herwig, F., Pignatari, M., …Ritter, C. (2018). Impact of rotation and magnetic fields in low mass AGB stars. . https://doi.org/10.1088/1742-6596/940/1/012038

After core helium burning in low and intermediate-mass stars, starts the AGB phase. In this phase, the s process takes place, which is believed to be at the origin of half of all elements heavier than iron. The role of rotation and magnetic fields on... Read More about Impact of rotation and magnetic fields in low mass AGB stars.

Nucleosynthesis in the first massive stars (2018)
Journal Article
Hirschi. (2018). Nucleosynthesis in the first massive stars. Journal of Physics: Conference Series, 012021 -?. https://doi.org/10.1088/1742-6596/940/1/012021

The nucleosynthesis in the first massive stars may be constrained by observing the surface composition of long-lived very iron-poor stars born around 10 billion years ago from material enriched by their ejecta. Many interesting clues on physical proc... Read More about Nucleosynthesis in the first massive stars.

Sensitivity to neutron captures and ß -decays of the enhanced s-process in rotating massive stars at low metallicities (2018)
Journal Article
Hirschi. (2018). Sensitivity to neutron captures and ß -decays of the enhanced s-process in rotating massive stars at low metallicities. Journal of Physics: Conference Series, 12051. https://doi.org/10.1088/1742-6596/940/1/012051

The s-process in massive stars, producing nuclei up to A ˜ 90, has a different behaviour at low metallicity if stellar rotation is significant. This enhanced s-process is distinct from the s-process in massive stars around solar metallicity, and deta... Read More about Sensitivity to neutron captures and ß -decays of the enhanced s-process in rotating massive stars at low metallicities.

Uncertainties in the production of p nuclides in thermonuclear supernovae determined by Monte Carlo variations (2017)
Journal Article
Nishimura(西村信哉), N., Rauscher, T., Hirschi, R., Murphy, A. S. J., Cescutti, G., & Travaglio, C. (2018). Uncertainties in the production of p nuclides in thermonuclear supernovae determined by Monte Carlo variations. Monthly Notices of the Royal Astronomical Society, 474(3), 3133 -3139. https://doi.org/10.1093/mnras/stx3033

Thermonuclear supernovae originating from the explosion of a white dwarf accreting mass from a companion star have been suggested as a site for the production of p nuclides. Such nuclei are produced during the explosion, in layers enriched with seed... Read More about Uncertainties in the production of p nuclides in thermonuclear supernovae determined by Monte Carlo variations.

Are some CEMP-s stars the daughters of spinstars? (2017)
Journal Article
Choplin, A., Hirschi, R., Meynet, G., & Ekström, S. (2017). Are some CEMP-s stars the daughters of spinstars?. Astronomy and Astrophysics, 607, Article L3. https://doi.org/10.1051/0004-6361/201731948

Carbon-enhanced metal-poor (CEMP)-s stars are long-lived low-mass stars with a very low iron content as well as overabundances of carbon and s-elements. Their peculiar chemical pattern is often explained by pollution from an asymptotic giant branch (... Read More about Are some CEMP-s stars the daughters of spinstars?.

Pre-supernova mixing in CEMP-no source stars (2017)
Journal Article
Choplin, A., Ekström, S., Meynet, G., Maeder, A., Georgy, C., & Hirschi, R. (2017). Pre-supernova mixing in CEMP-no source stars. Astronomy & Astrophysics, 605, A63 -A63. https://doi.org/10.1051/0004-6361/201630182

Context. CEMP-no stars are long-lived low-mass stars with a very low iron content, overabundances of carbon and no or minor signs for the presence of s- or r-elements. Although their origin is still a matter of debate, they are often considered as be... Read More about Pre-supernova mixing in CEMP-no source stars.

Pair-instability Supernova Simulations: Progenitor Evolution, Explosion, and Light Curves (2017)
Journal Article
Hirschi, R. (2017). Pair-instability Supernova Simulations: Progenitor Evolution, Explosion, and Light Curves. Astrophysical Journal, 100 - 100. https://doi.org/10.3847/1538-4357/aa8461

In recent years, the viability of the pair-instability supernova (PISN) scenario for explaining superluminous supernovae has all but disappeared except for a few slowly-evolving examples. However, PISNe are not predicted to be superluminous throughou... Read More about Pair-instability Supernova Simulations: Progenitor Evolution, Explosion, and Light Curves.

Testing a one-dimensional prescription of dynamical shear mixing with a two-dimensional hydrodynamic simulation (2017)
Journal Article
Edelman, P., Röpke, F., Hirschi, R., Georgy, C., & Jones, S. (2017). Testing a one-dimensional prescription of dynamical shear mixing with a two-dimensional hydrodynamic simulation. Astronomy and Astrophysics, 604, Article A25. https://doi.org/10.1051/0004-6361/201629873

Context. The treatment of mixing processes is still one of the major uncertainties in 1D stellar evolution models. This is mostly due to the need to parametrize and approximate aspects of hydrodynamics in hydrostatic codes. In particular, the effect... Read More about Testing a one-dimensional prescription of dynamical shear mixing with a two-dimensional hydrodynamic simulation.

3D hydrodynamic simulations of carbon burning in massive stars (2017)
Journal Article
Cristini, A., Meakin, C., Hirschi, R., Arnett, D., Georgy, C., Viallet, M., & Walkington, I. (2017). 3D hydrodynamic simulations of carbon burning in massive stars. Monthly Notices of the Royal Astronomical Society, 471(1), 279 -300. https://doi.org/10.1093/mnras/stx1535

We present the first detailed 3D hydrodynamic implicit large eddy simulations of turbulent convection of carbon burning in massive stars. Simulations begin with radial profiles mapped from a carbon-burning shell within a 15M circle dot 1D stellar evo... Read More about 3D hydrodynamic simulations of carbon burning in massive stars.

The neutron capture process in the He shell in core-collapse suprenovae: Presolar silicon carbide grains as a diagnostic tool for nuclear astrophysics (2017)
Journal Article
Pignatari, M., Hoppe, P., Trappitsch, R., Fryer, C., Timmes, F., Herwig, F., & Hirschi, R. (2017). The neutron capture process in the He shell in core-collapse suprenovae: Presolar silicon carbide grains as a diagnostic tool for nuclear astrophysics. Geochimica et Cosmochimica Acta, 221, 37-46. https://doi.org/10.1016/j.gca.2017.06.005

Carbon-rich presolar grains are found in primitive meteorites, with isotopic measurements to date suggesting a core-collapse supernovae origin site for some of them. This holds for about 1–2% of presolar silicon carbide (SiC) grains, so-called Type X... Read More about The neutron capture process in the He shell in core-collapse suprenovae: Presolar silicon carbide grains as a diagnostic tool for nuclear astrophysics.

Uncertainties in s-process nucleosynthesis in massive stars determined by Monte Carlo variations (2017)
Journal Article
Nishimura (西村信哉), N., Hirschi, R., Rauscher, T., Murphy, A., & Cescutti, G. (2017). Uncertainties in s-process nucleosynthesis in massive stars determined by Monte Carlo variations. Monthly Notices of the Royal Astronomical Society, 469(2), 1752 -1767. https://doi.org/10.1093/mnras/stx696

The s-process in massive stars produces the weak component of the s-process (nuclei up to A ~ 90), in amounts that match solar abundances. For heavier isotopes, such as barium, production through neutron capture is significantly enhanced in very meta... Read More about Uncertainties in s-process nucleosynthesis in massive stars determined by Monte Carlo variations.

A Chemical Signature from Fast-rotating Low-metallicity Massive Stars: ROA 276 inωCentauri (2017)
Journal Article
Yong, D., Norris, J. E., Da Costa, G. S., Stanford, L. M., Karakas, A. I., Shingles, L. J., …Pignatari, M. (2017). A Chemical Signature from Fast-rotating Low-metallicity Massive Stars: ROA 276 inωCentauri. Astrophysical Journal, 837(2), 176. https://doi.org/10.3847/1538-4357/aa6250

We present a chemical abundance analysis of a metal-poor star, ROA 276, in the stellar system ω Centauri. We confirm that this star has an unusually high [Sr/Ba] abundance ratio. Additionally, ROA 276 exhibits remarkably high abundance ratios, [X/Fe]... Read More about A Chemical Signature from Fast-rotating Low-metallicity Massive Stars: ROA 276 inωCentauri.

Possible pair-instability supernovae at solar metallicity from magnetic stellar progenitors (2017)
Journal Article
Georgy, C., Meynet, G., Ekström, S., Wade, G. A., Petit, V., Keszthelyi, Z., & Hirschi, R. (2017). Possible pair-instability supernovae at solar metallicity from magnetic stellar progenitors. Astronomy & Astrophysics, 599, Article L5. https://doi.org/10.1051/0004-6361/201730401

Near-solar metallicity (and low-redshift) pair-instability supernova (PISN) candidates challenge stellar evolution models. Indeed, at such a metallicity, even an initially very massive star generally loses so much mass by stellar winds that it will a... Read More about Possible pair-instability supernovae at solar metallicity from magnetic stellar progenitors.

Progenitors of Core-Collapse Supernovae (2017)
Journal Article
Hirschi, R., Arnett, D., Cristini, A., Georgy, C., Meakin, C., & Walkington, I. (2017). Progenitors of Core-Collapse Supernovae. Proceedings of the International Astronomical Union, 12(S331), 1-10. https://doi.org/10.1017/S1743921317004896

Massive stars have a strong impact on their surroundings, in particular when they produce a core-collapse supernova at the end of their evolution. In these proceedings, we review the general evolution of massive stars and their properties at collapse... Read More about Progenitors of Core-Collapse Supernovae.

Impact of Rotation and Convective Boundary Mixing in Low Mass AGB Stars (2017)
Journal Article
den Hartogh, J., Battino, U., Hirschi, R., Pignatari, M., & Herwig, F. (2017). Impact of Rotation and Convective Boundary Mixing in Low Mass AGB Stars. JPS Conference Proceedings, https://doi.org/10.7566/jpscp.14.020904

After central He burning exhaustion, stars with an initial mass of 1.5–3 solar masses start the AGB phase. In this phase, the s-process takes place, which is producing about half of all elements heavier than iron. We calculated non-rotating AGB stell... Read More about Impact of Rotation and Convective Boundary Mixing in Low Mass AGB Stars.

Impacts of Nuclear-Physics Uncertainty in Stellar Temperatures on the s-Process Nucleosynthesis (2017)
Journal Article
Nishimura, N., Cescutti, G., Hirschi, R., Rauscher, T., Den Hartogh, J., & Murphy, A. S. J. (2017). Impacts of Nuclear-Physics Uncertainty in Stellar Temperatures on the s-Process Nucleosynthesis. JPS Conference Proceedings, https://doi.org/10.7566/jpscp.14.020903

We evaluated the uncertainty relevant to s-process nucleosynthesis using a Monte-Carlo centred approach. We are based on a realistic and general prescription of temperature dependent uncertainty for the reactions. We considered massive stars for the... Read More about Impacts of Nuclear-Physics Uncertainty in Stellar Temperatures on the s-Process Nucleosynthesis.

Constraining the efficiency of angular momentum transport with asteroseismology of red giants: the effect of stellar mass (2017)
Journal Article
Eggenberger, P., Lagarde, N., Miglio, A., Montalbán, J., Ekström, S., Georgy, C., …Hirschi, R. (2017). Constraining the efficiency of angular momentum transport with asteroseismology of red giants: the effect of stellar mass. Astronomy & Astrophysics, 599, Article A18. https://doi.org/10.1051/0004-6361/201629459

Context. Constraints on the internal rotation of red giants are now available thanks to asteroseismic observations. Preliminary comparisons with rotating stellar models indicate that an undetermined additional process for the internal transport of an... Read More about Constraining the efficiency of angular momentum transport with asteroseismology of red giants: the effect of stellar mass.

Massive Star Evolution: What we do (not) know (2016)
Journal Article
Georgy, C., Hirschi, R., & Ekström, S. (2016). Massive Star Evolution: What we do (not) know. Proceedings of the Polish Astronomical Society, 5, 37-44

The modelling of massive star evolution is a complex task, and is very sensitive to the way physical processes (such as convection, rotation, mass loss, etc.) are included in stellar evolution code. Moreover, the very high observed fraction of binary... Read More about Massive Star Evolution: What we do (not) know.

The First 3D Simulations of Carbon Burning in a Massive Star (2016)
Conference Proceeding
Cristini, A., Meakin, C., Hirschi, R., Arnett, D., Georgy, C., & Viallet, M. (2016). The First 3D Simulations of Carbon Burning in a Massive Star. . https://doi.org/10.1017/s1743921317003441

We present the first detailed three-dimensional hydrodynamic implicit large eddy simulations of turbulent convection for carbon burning. The simulations start with an initial radial profile mapped from a carbon burning shell within a 15 M⊙ stellar ev... Read More about The First 3D Simulations of Carbon Burning in a Massive Star.

Fast evolving pair-instability supernova models: evolution, explosion, light curves (2016)
Journal Article
Kozyreva, A., Gilmer, M., Hirschi, R., Fröhlich, C., Blinnikov, S., Wollaeger, R. T., …Sorokina, E. (2017). Fast evolving pair-instability supernova models: evolution, explosion, light curves. Monthly Notices of the Royal Astronomical Society, 464(3), 2854-2865. https://doi.org/10.1093/mnras/stw2562

With an increasing number of superluminous supernovae (SLSNe) discovered, the question of their origin remains open and causes heated debates in the supernova community. Currently, there are three proposed mechanisms for SLSNe: (1) pair-instability s... Read More about Fast evolving pair-instability supernova models: evolution, explosion, light curves.

Looking for imprints of the first stellar generations in metal-poor bulge field stars (2016)
Journal Article
Hirschi. (2016). Looking for imprints of the first stellar generations in metal-poor bulge field stars. Astronomy and Astrophysics, https://doi.org/10.1051/0004-6361/201628104

Context. Efforts to look for signatures of the first stars have concentrated on metal-poor halo objects. However, the low end of the bulge metallicity distribution has been shown to host some of the oldest objects in the Milky Way and hence this Gala... Read More about Looking for imprints of the first stellar generations in metal-poor bulge field stars.

Uncertainties in the production of p nuclei in massive stars obtained from Monte Carlo variations (2016)
Journal Article
Rauscher, T., Nishimura, N., Hirschi, R., Cescutti, G., Murphy, A., & Heger, A. (2016). Uncertainties in the production of p nuclei in massive stars obtained from Monte Carlo variations. Monthly Notices of the Royal Astronomical Society, 463(4), 4153 - 4166. https://doi.org/10.1093/mnras/stw2266

Nuclear data uncertainties in the production of p nuclei in massive stars have been quantified in a Monte Carlo procedure. Bespoke temperature-dependent uncertainties were assigned to different types of reactions involving nuclei from Fe to Bi. Their... Read More about Uncertainties in the production of p nuclei in massive stars obtained from Monte Carlo variations.

Nugrid stellar data set. I. Stellar yields from H to BI for stars with metallicities z=0.02 and z=0.01 (2016)
Journal Article
Hirschi. (2016). Nugrid stellar data set. I. Stellar yields from H to BI for stars with metallicities z=0.02 and z=0.01. Astrophysical Journal Supplement, https://doi.org/10.3847/0067-0049/225/2/24

We provide a set of stellar evolution and nucleosynthesis calculations that applies established physics assumptions simultaneously to low- and intermediate-mass and massive star models. Our goal is to provide an internally consistent and comprehensiv... Read More about Nugrid stellar data set. I. Stellar yields from H to BI for stars with metallicities z=0.02 and z=0.01.

Application of a theory and simulation-based convective boundary mixing model for AGB star evolution and nucleosynthesis (2016)
Journal Article
Battino, U., Pignatari, M., Ritter, C., Herwig, F., Denisenkov, P., Den Hartogh, J., …Paxton, B. (2016). Application of a theory and simulation-based convective boundary mixing model for AGB star evolution and nucleosynthesis. Astrophysical Journal, 827(1), 30. https://doi.org/10.3847/0004-637X/827/1/30

The s-process nucleosynthesis in Asymptotic giant branch (AGB) stars depends on the modeling of convective boundaries. We present models and s-process simulations that adopt a treatment of convective boundaries based on the results of hydrodynamic si... Read More about Application of a theory and simulation-based convective boundary mixing model for AGB star evolution and nucleosynthesis.

Theory considerations for nucleosynthesis beyond Fe with special emphasis on p-nuclei in massive stars (2016)
Journal Article
Rauscher, T., Nishimura, N., & Hirschi, R. (2016). Theory considerations for nucleosynthesis beyond Fe with special emphasis on p-nuclei in massive stars. AIP conference proceedings, 1743(1), https://doi.org/10.1063/1.4953300

Nucleosynthesis of heavy elements requires the use of different experimental and theoretical methods to determine astrophysical reaction rates than light element nucleosynthesis. Additionally, there are also larger uncertainties involved in the astro... Read More about Theory considerations for nucleosynthesis beyond Fe with special emphasis on p-nuclei in massive stars.

Effects of Dimensionality on Pair-Instability Supernova Explosions (2016)
Presentation / Conference
Gilmer, M. S., Kozyreva, A., Hirschi, R., & Fröhlich, C. (2016, June). Effects of Dimensionality on Pair-Instability Supernova Explosions. Paper presented at Proceedings of the 14th International Symposium on Nuclei in the Cosmos (NIC2016), Toki Messe, Niigata, Japan

Since the emergence of the new class of extremely bright transients, super-luminous supernovae (SLSNe), three main mechanisms to power their light curves (LCs) have been discussed. They are the spin-down of a magnetar, interaction with circumstellar... Read More about Effects of Dimensionality on Pair-Instability Supernova Explosions.

Linking 1D evolutionary to 3D hydrodynamical simulations of massive stars (2016)
Journal Article
Hirschi. (2016). Linking 1D evolutionary to 3D hydrodynamical simulations of massive stars. Physica Scripta, 98-99. https://doi.org/10.1017/S1743921314006371

In this contribution we present initial results of a study on convective boundary mixing (CBM) in massive stellar models using the GENEVA stellar evolution code (Eggenberger et al.2008). Before undertaking costly 3D hydrodynamic simulations, it is im... Read More about Linking 1D evolutionary to 3D hydrodynamical simulations of massive stars.

How much radioactive nickel does ASASSN-15lh require? (2016)
Journal Article
Kozyreva, A., Hirschi, R., Blinnikov, S., & den Hartogh, J. (2016). How much radioactive nickel does ASASSN-15lh require?. Monthly Notices of the Royal Astronomical Society, 459(1), L21–L25. https://doi.org/10.1093/mnrasl/slw036

The discovery of the most luminous supernova ASASSN-15lh triggered a shock-wave in the supernova community. The three possible mechanisms proposed for the majority of other superluminous supernovae do not produce a realistic physical model for this p... Read More about How much radioactive nickel does ASASSN-15lh require?.

Linking 1D evolutionary to 3D hydrodynamical simulations of massive stars (2016)
Journal Article
Cristini, A., Meakin, C., Hirschi, R., Arnett, D., Georgy, C., & Viallet, M. (2016). Linking 1D evolutionary to 3D hydrodynamical simulations of massive stars. Physica Scripta, 91(3), 034006. https://doi.org/10.1088/0031-8949/91/3/034006

Stellar evolution models of massive stars are important for many areas of astrophysics, for example nucleosynthesis yields, supernova progenitor models and understanding physics under extreme conditions. Turbulence occurs in stars primarily due to nu... Read More about Linking 1D evolutionary to 3D hydrodynamical simulations of massive stars.

Wolf-Rayet stars as an evolved stage of stellar life (2016)
Conference Proceeding
Georgy, C., Ekström, S., Hirschi, R., Meynet, G., Groh, J., & Eggenberger, P. (2016). Wolf-Rayet stars as an evolved stage of stellar life. In Wolf-Rayet Stars: Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015

Wolf-Rayet (WR) stars, as they are advanced stages of the life of massive stars, provide a good test for various physical processes involved in the modelling of massive stars, such as rotation and mass loss. In this paper, we show the outputs of the... Read More about Wolf-Rayet stars as an evolved stage of stellar life.

s-process production in rotating massive stars at solar and low metallicities (2015)
Journal Article
Frischknecht, U., Hirschi, R., Pignatari, M., Maeder, A., Meynet, G., Chiappini, C., …Ekström, S. (2016). s-process production in rotating massive stars at solar and low metallicities. Monthly Notices of the Royal Astronomical Society, 456(2), 1803 - 1825. https://doi.org/10.1093/mnras/stv2723

Rotation was shown to have a strong impact on the structure and light element nucleosynthesis in massive stars. In particular, models including rotation can reproduce the primary nitrogen observed in halo extremely metal poor (EMP) stars. Additional... Read More about s-process production in rotating massive stars at solar and low metallicities.

Clues on the first stars from CEMP-no stars (2015)
Journal Article
Choplin, A., Meynet, G., Maeder, A., Hirschi, R., Ekström, S., & Chiappini, C. (2015). Clues on the first stars from CEMP-no stars. Proceedings of the International Astronomical Union, 11(S317), 282-283. https://doi.org/10.1017/s1743921315006808

The material used to form the CEMP-no stars presents signatures of processing by the CNO cycle and by He-burning from a previous stellar generation called spinstars. We compare the composition of the ejecta (wind + supernova) of a spinstar model to o... Read More about Clues on the first stars from CEMP-no stars.

CARBON-RICH PRESOLAR GRAINS FROM MASSIVE STARS: SUBSOLAR 12 C/ 13 C AND 14 N/ 15 N RATIOS AND THE MYSTERY OF 15 N (2015)
Journal Article
Pignatari, M., Zinner, E., Hoppe, P., Jordan, C. J., Gibson, B. K., Trappitsch, R., …Timmes, F. X. CARBON-RICH PRESOLAR GRAINS FROM MASSIVE STARS: SUBSOLAR 12 C/ 13 C AND 14 N/ 15 N RATIOS AND THE MYSTERY OF 15 N. Astrophysical Journal Letters, 808(2), L43. https://doi.org/10.1088/2041-8205/808/2/l43

The role of neutron star mergers in the chemical evolution of the Galactic halo (2015)
Journal Article
Hirschi. (2015). The role of neutron star mergers in the chemical evolution of the Galactic halo. Astronomy & Astrophysics, https://doi.org/10.1051/0004-6361/201525698

Context. The dominant astrophysical production site of the r-process elements has not yet been unambiguously identified. The suggested main r-process sites are core-collapse supernovae and merging neutron stars. Aims. We explore the problem of the... Read More about The role of neutron star mergers in the chemical evolution of the Galactic halo.

ERRATUM: “PAIR-INSTABILITY SUPERNOVAE IN THE LOCAL UNIVERSE” (2014, ApJ, 797, 9) (2015)
Journal Article
Whalen, D. J., Smidt, J., Heger, A., Hirschi, R., Yusof, N., Even, W., …Joggerst, C. C. (2015). ERRATUM: “PAIR-INSTABILITY SUPERNOVAE IN THE LOCAL UNIVERSE” (2014, ApJ, 797, 9). Astrophysical Journal, 801(1), 71. https://doi.org/10.1088/0004-637x/801/1/71

Linking 1D Stellar Evolution to 3D Hydrodynamical Simulations (2015)
Journal Article
Hirschi, R. (2015). Linking 1D Stellar Evolution to 3D Hydrodynamical Simulations. Proceedings of the International Astronomical Union, 98-99. https://doi.org/10.1017/S1743921314006371

In this contribution we present initial results of a study on convective boundary mixing (CBM) in massive stellar models using the GENEVA stellar evolution code. Before undertaking costly 3D hydrodynamic simulations, it is important to study the gene... Read More about Linking 1D Stellar Evolution to 3D Hydrodynamical Simulations.

Code dependencies of pre-supernova evolution and nucleosynthesis in massive stars: Evolution to the end of core helium burning (2015)
Journal Article
Jones, S., Hirschi, R., Pignatari, M., Heger, A., Georgy, C., Nishimura, N., …Herwig, F. (2015). Code dependencies of pre-supernova evolution and nucleosynthesis in massive stars: Evolution to the end of core helium burning. Monthly Notices of the Royal Astronomical Society, 447(4), 3115-3129. https://doi.org/10.1093/mnras/stu2657

Massive stars are key sources of radiative, kinetic, and chemical feedback in the universe. Grids of massive star models computed by different groups each using their own codes, input physics choices and numerical approximations, however, lead to inc... Read More about Code dependencies of pre-supernova evolution and nucleosynthesis in massive stars: Evolution to the end of core helium burning.

Evolution and Nucleosynthesis of Very Massive Stars (2015)
Book Chapter
Hirschi, R. (2015). Evolution and Nucleosynthesis of Very Massive Stars. In Very Massive Stars in the Local Universe (157-198)

The final fate of stars that ignite neon and oxygen off-center: electron capture or iron core-collapse supernova? (2014)
Journal Article
Jones, S., Hirschi, R., & Nomoto, K. (2014). The final fate of stars that ignite neon and oxygen off-center: electron capture or iron core-collapse supernova?. Astrophysical Journal, 797(2), 83. https://doi.org/10.1088/0004-637X/797/2/83

In the ONeMg cores of $8.8-9.5~{\rm M}_\odot$ stars, neon and oxygen burning is ignited off-center. Whether the neon-oxygen flame propagates to the center is critical to determine whether these stars undergo Fe core collapse or electron capture induc... Read More about The final fate of stars that ignite neon and oxygen off-center: electron capture or iron core-collapse supernova?.

Pair-instability supernovae in the local universe (2014)
Journal Article
Whalen, D. J., Smidt, J., Heger, A., Hirschi, R., Yusof, N., Even, W., …Joggerst, C. C. (2014). Pair-instability supernovae in the local universe. Astrophysical Journal, 797(1), Article 9. https://doi.org/10.1088/0004-637X/797/1/9

The discovery of 150-300 M ? stars in the Local Group and pair-instability supernova candidates at low redshifts has excited interest in this exotic explosion mechanism. Realistic light curves for pair-instability supernovae at near-solar metalliciti... Read More about Pair-instability supernovae in the local universe.

High-resolution abundance analysis of red giants in the globular cluster NGC 6522 (2014)
Journal Article
Barbuy, B., Chiappini, C., Cantelli, E., Depagne, E., Pignatari, M., Hirschi, R., …Gómez, A. (2014). High-resolution abundance analysis of red giants in the globular cluster NGC 6522. Astronomy & Astrophysics, 570, A76. https://doi.org/10.1051/0004-6361/201424311

Context. The [Sr/Ba] and [Y/Ba] scatter observed in some galactic halo stars that are very metal-poor and in a few individual stars of the oldest known Milky Way globular cluster NGC 6522 have been interpreted as evidence of early enrichment by massi... Read More about High-resolution abundance analysis of red giants in the globular cluster NGC 6522.

The s-process enrichment of the globular clusters M4 and M22 (2014)
Journal Article
Hirschi. (2014). The s-process enrichment of the globular clusters M4 and M22. Astrophysical Journal, https://doi.org/10.1088/0004-637X/795/1/34

We investigate the enrichment in elements produced by the slow neutron-capture process (s-process) in the globular clusters M4 (NGC 6121) and M22 (NGC 6656). Stars in M4 have homogeneous abundances of Fe and neutron-capture elements, but the entire c... Read More about The s-process enrichment of the globular clusters M4 and M22.

Production of 92Nb, 92Mo, and 146Sm in the gamma-process in SNIa (2014)
Presentation / Conference
Rauscher, T., Travaglio, C., Gallino, R., Nishimura, N., & Hirschi, R. (2014, July). Production of 92Nb, 92Mo, and 146Sm in the gamma-process in SNIa. Paper presented at 13th Symposium on Nuclei in the Cosmos (NIC XIII), Debrecen, Hungary

The knowledge of the production of extinct radioactivities like 92Nb and 146Sm by photodisintegration processes in ccSN and SNIa models is essential for interpreting abundances in meteoritic material and for Galactic Chemical Evolution (GCE). The 92M... Read More about Production of 92Nb, 92Mo, and 146Sm in the gamma-process in SNIa.

Impact of the uncertainty in α-captures on 22Ne on the weak s-process in massive stars (2014)
Journal Article
Nishimura, N., Hirschi, R., Pignatari, M., Herwig, F., Beard, M., Imbriani, G., …Wiescher, M. (2014). Impact of the uncertainty in α-captures on 22Ne on the weak s-process in massive stars. AIP conference proceedings, 1594(1), https://doi.org/10.1063/1.4874059

Electron Capture and Beta-Decay Rates for the Collapse of O+Ne+Mg Cores (2014)
Journal Article
Hua Lam, Y., Martínez-Pinedo, G., Langanke, K., Jones, S., Hirschi, R., Zegers, R. G. T., & Alex Brown, B. (2014). Electron Capture and Beta-Decay Rates for the Collapse of O+Ne+Mg Cores. EPJ Web of Conferences, 66, Article 07011. https://doi.org/10.1051/epjconf/20146607011

We present a new set of electron (e−) capture and β-decay rates that improves previous calculations by Takahara et al. and Oda et al. by: (a) incorporation of recent charge-exchange and β-decay data, (b) contributions of forbidden transitions, and (c... Read More about Electron Capture and Beta-Decay Rates for the Collapse of O+Ne+Mg Cores.

Evolution and Nucleosynthesis of Very Massive Stars (2014)
Book Chapter
Hirschi, R. (2014). Evolution and Nucleosynthesis of Very Massive Stars. In Very Massive Stars in the Local Universe (157-198). (1). Springer. https://doi.org/10.1007/978-3-319-09596-7_6

In this chapter, after a brief introduction and overview of stellar evolution, we discuss the evolution and nucleosynthesis of very massive stars (VMS: M>100 solar masses) in the context of recent stellar evolution model calculations. This chapter co... Read More about Evolution and Nucleosynthesis of Very Massive Stars.

Grids of stellar models with rotation - III. Models from 0.8 to 120 Msun at a metallicity Z = 0.002 (2013)
Journal Article
Georgy, C., Ekström, S., Eggenberger, P., Meynet, G., Haemmerlé, L., Maeder, A., …Barblan, F. (2013). Grids of stellar models with rotation - III. Models from 0.8 to 120 Msun at a metallicity Z = 0.002. Astronomy & Astrophysics, 558, Article A103. https://doi.org/10.1051/0004-6361/201322178

(shortened) We provide a grid of single star models covering a mass range from 0.8 to 120 Msun with an initial metallicity Z = 0.002 with and without rotation. We discuss the impact of a change in the metallicity by comparing the current tracks with... Read More about Grids of stellar models with rotation - III. Models from 0.8 to 120 Msun at a metallicity Z = 0.002.

ADVANCED BURNING STAGES AND FATE OF 8-10M☉STARS (2013)
Journal Article
Jones, S., Hirschi, R., Nomoto, K., Fischer, T., Timmes, F. X., Herwig, F., …Bertolli, M. G. (in press). ADVANCED BURNING STAGES AND FATE OF 8-10M☉STARS. Astrophysical Journal, 772(2), 150. https://doi.org/10.1088/0004-637x/772/2/150

The reaction of either 4,4′,6,6′-tetramethyl-2,2′-bipyridine, L, or 4,4′,6,6′-tetracarboxy-2,2′-bipyridine, H4L, with Cu(OAc)2·H2O under acidic hydrothermal conditions (50:1 H2O/HNO3; 160 °C) led to the formation of crystalline {[Cu(HL′)(H2O)]·H2O},... Read More about ADVANCED BURNING STAGES AND FATE OF 8-10M☉STARS.

Detailedβ-transition rates for URCA nuclear pairs in 8–10 solar-mass stars (2013)
Journal Article
Toki, H., Suzuki, T., Nomoto, K., Jones, S., & Hirschi, R. Detailedβ-transition rates for URCA nuclear pairs in 8–10 solar-mass stars. Physical Review C - Nuclear Physics, 88(1), Article 015806. https://doi.org/10.1103/physrevc.88.015806

We calculate β-transition rates for URCA nuclear pairs using the sd-shell-model framework of Wildenthal [B. H. Widenthal, Prog. Part. Nucl. Phys. 11, 5 (1984)] with the modified Hamiltonian. We consider many β transitions including excited states nec... Read More about Detailedβ-transition rates for URCA nuclear pairs in 8–10 solar-mass stars.

SILICON CARBIDE GRAINS OF TYPE C PROVIDE EVIDENCE FOR THE PRODUCTION OF THE UNSTABLE ISOTOPE 32 Si IN SUPERNOVAE (2013)
Journal Article
Pignatari, M., Zinner, E., Bertolli, M. G., Trappitsch, R., Hoppe, P., Rauscher, T., …Thielemann, F. (in press). SILICON CARBIDE GRAINS OF TYPE C PROVIDE EVIDENCE FOR THE PRODUCTION OF THE UNSTABLE ISOTOPE 32 Si IN SUPERNOVAE. Astrophysical Journal Letters, 771(1), L7. https://doi.org/10.1088/2041-8205/771/1/l7

Carbon-rich grains are observed to condense in the ejecta of recent core-collapse supernovae (SNe) within a year after the explosion. Silicon carbide grains of type X are C-rich grains with isotopic signatures of explosive SN nucleosynthesis have bee... Read More about SILICON CARBIDE GRAINS OF TYPE C PROVIDE EVIDENCE FOR THE PRODUCTION OF THE UNSTABLE ISOTOPE 32 Si IN SUPERNOVAE.

Evolution and fate of very massive stars (2013)
Journal Article
Yusof, N., Hirschi, R., Meynet, G., Crowther, P. A., Ekström, S., Frischknecht, U., …Schnurr, O. (2013). Evolution and fate of very massive stars. Monthly Notices of the Royal Astronomical Society, 433(2), 1114-1132. https://doi.org/10.1093/mnras/stt794

There is observational evidence that supports the existence of Very Massive Stars in the local universe. First, very massive stars (Mini

The Chemical Evolution of Heavy Elements in Globular Clusters (2013)
Conference Proceeding
Shingles, L. J., Karakas, A. I., & Hirschi, R. (2013). The Chemical Evolution of Heavy Elements in Globular Clusters. . https://doi.org/10.1017/s1743921313007059

We present preliminary results from a chemical evolution model that tracks the composition of heavy elements beyond iron in a globular cluster. The heavy elements can be used as tracers of the nucleosynthetic events that defined the formation and evo... Read More about The Chemical Evolution of Heavy Elements in Globular Clusters.

Thes-process in the Galactic halo: the fifth signature of spinstars in the early Universe? (2013)
Journal Article
Cescutti, G., Chiappini, C., Hirschi, R., Meynet, G., & Frischknecht, U. (2013). Thes-process in the Galactic halo: the fifth signature of spinstars in the early Universe?. Astronomy & Astrophysics, 553, Article A51. https://doi.org/10.1051/0004-6361/201220809

Context. Very old halo stars have previously been found to show at least four different abundance anomalies, which models of fast-rotating massive stars (spinstars) can successfully account for: rise of N/O and C/O, low 12C/13C, and a primary-like ev... Read More about Thes-process in the Galactic halo: the fifth signature of spinstars in the early Universe?.

PRODUCTION OF CARBON-RICH PRESOLAR GRAINS FROM MASSIVE STARS (2013)
Journal Article
Pignatari, M., Wiescher, M., Timmes, F. X., de Boer, R. J., Thielemann, F., Fryer, C., …Hirschi, R. (in press). PRODUCTION OF CARBON-RICH PRESOLAR GRAINS FROM MASSIVE STARS. Astrophysical Journal Letters, 767(2), L22. https://doi.org/10.1088/2041-8205/767/2/l22

About a year after core-collapse supernova, dust starts to condense in the ejecta. In meteorites, a fraction of C-rich presolar grains (e.g., silicon carbide (SiC) grains of Type-X and low density graphites) are identified as relics of these events,... Read More about PRODUCTION OF CARBON-RICH PRESOLAR GRAINS FROM MASSIVE STARS.

THE12C +12C REACTION AND THE IMPACT ON NUCLEOSYNTHESIS IN MASSIVE STARS (2012)
Journal Article
Pignatari, M., Hirschi, R., Wiescher, M., Gallino, R., Bennett, M., Beard, M., …Timmes, F. X. (2013). THE12C +12C REACTION AND THE IMPACT ON NUCLEOSYNTHESIS IN MASSIVE STARS. Astrophysical Journal, 762(1), 31. https://doi.org/10.1088/0004-637x/762/1/31

Despite much effort in the past decades, the C-burning reaction rate is uncertain by several orders of magnitude, and the relative strength between the different channels 12C(12C, α)20Ne, 12C(12C, p)23Na, and 12C(12C, n)23Mg is poorly determined. Add... Read More about THE12C +12C REACTION AND THE IMPACT ON NUCLEOSYNTHESIS IN MASSIVE STARS.

Red Supergiants, Luminous Blue Variables and Wolf-Rayet stars: the single massive star perspective (2011)
Journal Article
Meynet, G., Georgy, C., Hirschi, R., Maeder, A., Massey, P., Przybilla, N., & Nieva, M. (2011). Red Supergiants, Luminous Blue Variables and Wolf-Rayet stars: the single massive star perspective. Bulletin de la Société Royale des Sciences de Liège, 80, 266-278

We discuss, in the context of the single star scenario, the nature of the progenitors of Red Supergiants (RSG), of Luminous Blue Variables (LBV) and of Wolf-Rayet (WR) stars. These three different populations correspond to evolved phases of Main Sequ... Read More about Red Supergiants, Luminous Blue Variables and Wolf-Rayet stars: the single massive star perspective.

The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 Msun stellar mass limit (2010)
Journal Article
Hirschi. (2010). The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 Msun stellar mass limit. Monthly Notices of the Royal Astronomical Society, 731 -751. https://doi.org/10.1111/j.1365-2966.2010.17167.x

Spectroscopic analyses of H-rich WN5-6 stars within the young star clusters NGC 3603 and R136 are presented, using archival HST & VLT spectroscopy, & high spatial resolution near-IR photometry. We derive high T* for the WN stars in NGC 3603 (T*~42+/-... Read More about The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 Msun stellar mass limit.

Origin of CEMP stars: What helium and lithium can tell us about CEMP stars? (2010)
Journal Article
Meynet, G., Hirschi, R., Ekstrom, S., Maeder, A., Georgy, C., Eggenberger, P., & Chiappini, C. (2010). Origin of CEMP stars: What helium and lithium can tell us about CEMP stars?. Proceedings of the International Astronomical Union, 268, 141-146. https://doi.org/10.1017/S1743921310003984

We show that the peculiar surface abundance patterns of Carbon Enhanced Metal Poor (CEMP) stars has been inherited from material having been processed by H- and He-burning phases in a previous generation of stars (hereafter called the ``Source Stars'... Read More about Origin of CEMP stars: What helium and lithium can tell us about CEMP stars?.

Massive Stars as Cosmic Engines through the Ages (2008)
Journal Article
Hirschi, R. (2008). Massive Stars as Cosmic Engines through the Ages. Proceedings of the International Astronomical Union, 3-16. https://doi.org/10.1017/S1743921308020292

Some useful developments in the model physics are briefly presented, followed by model results on chemical enrichments and WR stars. We discuss the expected rotation velocities of WR stars. We emphasize that the (C+O)/He ratio is a better chemical in... Read More about Massive Stars as Cosmic Engines through the Ages.

NuGrid: s process in massive stars (2008)
Journal Article
Frischknecht, U., Thielemann, F., -K. Thielemann, F., Pignatari, M., Bennett, M., Diehl, S., …Hirschi, R. NuGrid: s process in massive stars. Manuscript submitted for publication

The s-process production in massive stars at very low metallicities is expected to be negligible due to the low abundance of the neutron source 22Ne, to primary neutron poisons and decreasing iron seed abundances. However, recent models of massive st... Read More about NuGrid: s process in massive stars.

Nucleosynthesis simulations for a wide range of nuclear production sites from NuGrid (2008)
Journal Article
Herwig, F., Fryer, C., Hirschi, R., Bennett, M., L. Fryer, C., Diehl, S., …Young, P. Nucleosynthesis simulations for a wide range of nuclear production sites from NuGrid. Manuscript submitted for publication

Simulations of nucleosynthesis in astrophysical environments are at the intersection of nuclear physics reaction rate research and astrophysical applications, for example in the area of galactic chemical evolution or near-field cosmology. Unfortunate... Read More about Nucleosynthesis simulations for a wide range of nuclear production sites from NuGrid.

The impact of reduced mass loss rates on the evolution of massive stars (2008)
Conference Proceeding
Hirschi, R. (2008). The impact of reduced mass loss rates on the evolution of massive stars.

Mass loss is a very important aspect of the life of massive stars. After briefly reviewing its importance, we discuss the impact of the recently proposed downward revision of mass loss rates due to clumping (difficulty to form Wolf-Rayet stars and pr... Read More about The impact of reduced mass loss rates on the evolution of massive stars.

The s process in massive stars at low metallicity. Effect of primary N14 from fast rotating stars (2008)
Journal Article
Pignatari, M., Gallino, R., Meynet, G., Hirschi, R., Herwig, F., & Wiescher, M. (2008). The s process in massive stars at low metallicity. Effect of primary N14 from fast rotating stars. Astrophysical Journal, https://doi.org/10.1086/593350

The goal of this paper is to analyze the impact of a primary neutron source on the s-process nucleosynthesis in massive stars at halo metallicity. Recent stellar models including rotation at very low metallicity predict a strong production of primary... Read More about The s process in massive stars at low metallicity. Effect of primary N14 from fast rotating stars.

Difficulties in Probing Nuclear Physics: A Study of Ti and Ni (2008)
Presentation / Conference
Hungerford, A., Fryer, C. L., Timmes, F. X., Young, P., Bennett, M., Diehl, S., …Rockefeller, G. (2008, July). Difficulties in Probing Nuclear Physics: A Study of Ti and Ni. Paper presented at 10th Symposium on Nuclei in the Cosmos, Mackinac Island, Michigan, USA

The nucleosynthetic yield from a supernova explosion depends upon a variety of effects: progenitor evolution, explosion process, details of the nuclear network, and nuclear rates. Especially in studies of integrated stellar yields, simplifications re... Read More about Difficulties in Probing Nuclear Physics: A Study of Ti and Ni.

44Ti and 56Ni in core-collapse supernovae (2008)
Presentation / Conference
Magkotsios, G., Timmes, F. X., Wiescher, M., Fryer, C. L., Hungerford, A., Young, P., …Rockefeller, G. (2008, July). 44Ti and 56Ni in core-collapse supernovae. Paper presented at 10th Symposium on Nuclei in the Cosmos, Mackinac Island, Michigan, USA

We investigate the physical conditions where 44Ti and 56Ni are created in core-collapse supernovae. In this preliminary work we use a series of post-processing network calculations with parametrized expansion profiles that are representative of the w... Read More about 44Ti and 56Ni in core-collapse supernovae.

Stellar Evolution in the Early Universe (2008)
Journal Article
Hirschi, R., Frischknecht, U., -K. Thielemann, F., Pignatari, M., Chiappini, C., Ekstroem, S., …Maeder, A. (2008). Stellar Evolution in the Early Universe. Proceedings of the International Astronomical Union, 4(S255), https://doi.org/10.1017/S1743921308024976

Massive stars played a key role in the early evolution of the Universe. They formed with the first halos and started the re-ionisation. It is therefore very important to understand their evolution. In this paper, we describe the strong impact of rota... Read More about Stellar Evolution in the Early Universe.

Developments in physics of massive stars (2007)
Conference Proceeding
Meynet, G., Ekström, S., Maeder, A., Hirschi, R., Georgy, C., & Beffa, C. (2007). Developments in physics of massive stars. . https://doi.org/10.1017/S1743921308020449

New constraints on stellar models are provided by large surveys of massive stars, interferometric observations and asteroseismology. After a review of the main results so far obtained, we present new results from rotating models and discuss compariso... Read More about Developments in physics of massive stars.

Stellar Evolution at Low Metallicity (2007)
Journal Article
Hirschi, R., Chiappini, C., Meynet, G., Maeder, A., & Ekstrom, S. (2007). Stellar Evolution at Low Metallicity. Proceedings of the International Astronomical Union, 3(S250), https://doi.org/10.1017/S1743921308020528

Massive stars played a key role in the early evolution of the Universe. They formed with the first halos and started the re-ionisation. It is therefore very important to understand their evolution. In this review, we first recall the effect of metall... Read More about Stellar Evolution at Low Metallicity.

Mass loss and very low-metallicity stars (2007)
Journal Article
Hirschi, R., Chiappini, C., Meynet, G., Ekstrom, S., & Maeder, A. (2007). Mass loss and very low-metallicity stars. AIP conference proceedings, 948, 397–404. https://doi.org/10.1063/1.2818999

Mass loss plays a dominant role in the evolution of massive stars at solar metallicity. After discussing different mass loss mechanisms and their metallicity dependence, we present the possibility of strong mass loss at very low metallicity. Our mode... Read More about Mass loss and very low-metallicity stars.

GRB progenitors at low metallicities (2007)
Journal Article
Hirschi, R., Meynet, G., & Maeder, A. (2007). GRB progenitors at low metallicities. IL NUOVO CIMENTO B, 10-11, 1183-1187. https://doi.org/10.1393/ncb/i2007-10237-6

We calculated pre-supernova evolution models of single rotating massive stars. These models reproduce observations during the early stages of the evolution very well, in particular Wolf--Rayet (WR) populations and ratio between type II and type Ib,c... Read More about GRB progenitors at low metallicities.

Very low metallicity massive star models: Pre-SN evolution and primary nitrogen production (2006)
Journal Article
Hirschi, R. Very low metallicity massive star models: Pre-SN evolution and primary nitrogen production. https://doi.org/10.1051/0004-6361%3A20065356. Manuscript submitted for publication

Two series of models were computed. The first series consists of 20 solar mass models with varying initial metallicity (Z=0.02 down to Z=10^{-8}) and rotation (V_{ini}=0-600 km/s). The second one consists of models with an initial metallicity of Z=10... Read More about Very low metallicity massive star models: Pre-SN evolution and primary nitrogen production.

Rotating massive stars @ very low Z: high C and N production (2006)
Conference Proceeding
Hirschi, R. (2006). Rotating massive stars @ very low Z: high C and N production. . https://doi.org/10.1063/1.2234385

Two series of models and their yields are presented in this paper. The first series consists of 20 Mo models with varying initial metallicity (solar down to $Z=10^{-8}$) and rotation (Vini=0-600 km/s). The second one consists of models with an initia... Read More about Rotating massive stars @ very low Z: high C and N production.

Stellar evolution of massive stars at very low metallicities (2006)
Book Chapter
Hirschi, R., Fröhlich, C., Liebendörfer, M., & -K. Thielemann, F. (2006). Stellar evolution of massive stars at very low metallicities. In Reviews in Modern Astronomy. Wiley. https://doi.org/10.1002/9783527619030.ch5

Recently, measurements of abundances in extremely metal poor (EMP) stars have brought new constraints on stellar evolution models. In an attempt to explain the origin of the abundances observed, we computed pre--supernova evolution models, explosion... Read More about Stellar evolution of massive stars at very low metallicities.

Pre-supernova models at very low metallicity (2006)
Presentation / Conference
Hirschi, R. (2006, June). Pre-supernova models at very low metallicity

A series of fast rotating models at very low metallicity (Z=1e-8) was computed in order to explain the surface abundances observed at the surface of CEMP stars, in particular for nitrogen. The main results are the following: - Strong mixing occurs... Read More about Pre-supernova models at very low metallicity.

Pre-suprenova evolution of rotating massive stars (2005)
Conference Proceeding
Hirschi, R., Meynet, G., Maeder, A., & Goriely, S. (2005). Pre-suprenova evolution of rotating massive stars. . https://doi.org/10.1007/3-540-26633-X_28

The Geneva evolutionary code has been modified to study the advanced stages (Ne, O, Si burnings) of rotating massive stars. Here we present the results of four 20 solar mass stars at solar metallicity with initial rotational velocities of 0, 100, 200... Read More about Pre-suprenova evolution of rotating massive stars.

PopII 1/2 stars: very high N14 and low O16 yields (2005)
Journal Article
Hirschi, R. (2005). PopII 1/2 stars: very high N14 and low O16 yields. Proceedings of the International Astronomical Union, 1(S228), https://doi.org/10.1017/S1743921305005922

Nine 20 Mo models were computed with metallicities ranging from solar, through $Z=10^{-5}$ ([Fe/H]=~-3.1) down to $Z=10^{-8}$ ([Fe/H]=~-6.1) and with initial rotational velocities between 0 and 600 km/s to study the impact of initial metallicity and... Read More about PopII 1/2 stars: very high N14 and low O16 yields.

Stellar evolution with rotation XIII: Predicted GRB rates at various Z (2005)
Journal Article
Hirschi, R., Meynet, G., & Maeder, A. (2005). Stellar evolution with rotation XIII: Predicted GRB rates at various Z. Astronomy & Astrophysics, 443(2), https://doi.org/10.1051/0004-6361%3A20053329

We present the evolution of rotation in models of massive single stars covering a wide range of masses and metallicities. These models reproduce very well observations during the early stages of the evolution (in particular WR populations and ratio b... Read More about Stellar evolution with rotation XIII: Predicted GRB rates at various Z.

Rotating massive stars: Pre-SN models and stellar yields at solar metallicity (2005)
Journal Article
Hirschi, R., Meynet, G., & Maeder, A. (2005). Rotating massive stars: Pre-SN models and stellar yields at solar metallicity. Nuclear Physics A, 758, 234-237. https://doi.org/10.1016/j.nuclphysa.2005.05.041

We present a new set of stellar yields obtained from rotating stellar models at solar metallicity covering the massive star range (9-120 solar masses). The stellar models were calculated with the latest version of the Geneva stellar evolution code de... Read More about Rotating massive stars: Pre-SN models and stellar yields at solar metallicity.

Dynamical shear instability (2004)
Journal Article
Hirschi, R., Maeder, A., & Meynet, G. (2004). Dynamical shear instability. Proceedings of the International Astronomical Union, 215, 510 - 511

The dynamical shear instability is an important mixing process in the advanced stages of the evolution of massive stars. We calculated different models of 15 Mo with an initial rotational velocity, v(rot,ini)= 300 km/s to investigate its efficiency.... Read More about Dynamical shear instability.

Yields of rotating stars at solar metallicity (2004)
Journal Article
Hirschi, R., Meynet, G., & Maeder, A. Yields of rotating stars at solar metallicity. https://doi.org/10.1051/0004-6361%3A20041554. Manuscript submitted for publication

We present a new set of stellar yields obtained from rotating stellar models at solar metallicity covering the massive star range (12-60 solar masses). The stellar models were calculated with the latest version of the Geneva stellar evolution code de... Read More about Yields of rotating stars at solar metallicity.

Stellar evolution with rotation XII: Pre-supernova models (2004)
Journal Article
Hirschi, R., Meynet, G., & Maeder, A. (2004). Stellar evolution with rotation XII: Pre-supernova models. Astronomy & Astrophysics, 425, 649-670. https://doi.org/10.1051/0004-6361%3A20041095

We describe the latest developments of the Geneva stellar evolution code in order to model the pre-supernova evolution of rotating massive stars. Rotating and non-rotating stellar models at solar metallicity with masses equal to 12, 15, 20, 25, 40 an... Read More about Stellar evolution with rotation XII: Pre-supernova models.

The Stardome: using exoplanet research as a gateway into Science and Higher Education.
Digital Artefact
Hirschi, & Jeffries. (2021). The Stardome: using exoplanet research as a gateway into Science and Higher Education

Impact REF21; KEELE_PUBLIC_ENGAGEMENT_STARDOME_PROJECT

Evolution and Nucleosynthesis of Massive Stars
Conference Proceeding
Meynet, G., Maeder, A., Choplin, A., Takahashi, K., Ekström, S., Hirschi, R., …Eggenberger, P. (2017). Evolution and Nucleosynthesis of Massive Stars. . https://doi.org/10.7566/jpscp.14.010401

Massive stars are rapid nuclear reactors that play a key role in injecting new synthesized elements in the interstellar medium. Depending on the strengths of the stellar winds on the efficiency of mixing processes, the masses and the chemical composi... Read More about Evolution and Nucleosynthesis of Massive Stars.

Insights on the First Stars from CEMP-no Stars
Journal Article
Choplin, A., Meynet, G., Maeder, A., Hirschi, R., Ekström, S., & Chiappini, C. (2017). Insights on the First Stars from CEMP-no Stars. JPS Conference Proceedings, https://doi.org/10.7566/jpscp.14.020202

CEMP-no stars (Carbon-Enhanced metal-poor stars with no or few s- or r-elements) are long-lived low mass stars presenting a very low iron content and overabundances of carbon relatively to the sun. Their chemically peculiar abundance pattern could be... Read More about Insights on the First Stars from CEMP-no Stars.

Production Uncertainties of p-Nuclei in the γ-Process in Massive Stars Using a Monte Carlo Approach
Conference Proceeding
Rauscher, T., Nishimura, N., Hirschi, R., Cescutti, G., Murphy, A. S. J., & Heger, A. (2017). Production Uncertainties of p-Nuclei in the γ-Process in Massive Stars Using a Monte Carlo Approach. In Proceedings of the 14th International Symposium on Nuclei in the Cosmos (NIC2016). https://doi.org/10.7566/jpscp.14.010509

Proton-rich nuclei, the so-called p-nuclei, are made in photodisintegration processes in outer shells of massive stars in the course of the final supernova explosion. Nuclear uncertainties in the production of these nuclei have been quantified in a M... Read More about Production Uncertainties of p-Nuclei in the γ-Process in Massive Stars Using a Monte Carlo Approach.