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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.

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.

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.

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.

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-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.

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.