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.

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.

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?.

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.

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.

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.

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.

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.

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<=320 M) have been observed in the Large Magellanic Cloud . Second, there are observed SNe that bear the character...