Exact and approximate relations for the spin-dependence of the exchange energy in high magnetic fields (2009)
Journal Article
(2009). Exact and approximate relations for the spin-dependence of the exchange energy in high magnetic fields. International Journal of Modern Physics B, 3004 - 3008. https://doi.org/10.1142/S0217979209062712

The exchange energy of an arbitrary collinear-spin many-body system in an external magnetic field is a functional of the spin-resolved charge and current densities. Within the framework of density-functional theory (DFT), we show that the dependence... Read More about Exact and approximate relations for the spin-dependence of the exchange energy in high magnetic fields.

The low-mass Initial Mass Function in the young cluster NGC 6611 (2009)
Journal Article
Jeffries, M. Oliveira, J., D. Jeffries, R., & Th. van Loon, J. (2009). The low-mass Initial Mass Function in the young cluster NGC 6611. Monthly Notices of the Royal Astronomical Society, 1034-1050. https://doi.org/10.1111/j.1365-2966.2008.14140.x

NGC 6611 is the massive young cluster (2-3 Myr) that ionises the Eagle Nebula. We present very deep photometric observations of the central region of NGC 6611 obtained with the Hubble Space Telescope and the following filters: ACS/WFC F775W and F850L... Read More about The low-mass Initial Mass Function in the young cluster NGC 6611.

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., -K. Thielemann, F., Pignatari, M., Bennett, M., Diehl, S., Fryer, C., L. Fryer, C., Herwig, F., Hungerford, A., Magkotsios, G., Rockefeller, G., Timmes, F., Young, P., X. Timmes, F., & 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., Hungerford, A., Magkotsios, G., Pignatari, M., Rockefeller, G., Timmes, F., X. Timmes, F., & 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.

Contribution of the second Landau level to the exchange energy of the three-dimensional electron gas in a high magnetic field (2008)
Journal Article
(2008). Contribution of the second Landau level to the exchange energy of the three-dimensional electron gas in a high magnetic field. Physical review B: Condensed matter and materials physics, https://doi.org/10.1103/PhysRevB.78.085107

We derive a closed analytical expression for the exchange energy of the three-dimensional interacting electron gas in strong magnetic fields, which goes beyond the quantum limit (L=0) by explicitly including the effect of the second, L=1, Landau lev... Read More about Contribution of the second Landau level to the exchange energy of the three-dimensional electron gas in a high magnetic field.

Difficulties in Probing Nuclear Physics: A Study of Ti and Ni (2008)
Presentation / Conference Contribution
Hungerford, A., Fryer, C. L., Timmes, F. X., Young, P., Bennett, M., Diehl, S., Herwig, F., Hirschi, R., Pignatari, M., Magkotsios, G., & 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 Contribution
Magkotsios, G., Timmes, F. X., Wiescher, M., Fryer, C. L., Hungerford, A., Young, P., Bennett, M., Diehl, S., Herwig, F., Hirschi, R., Pignatari, M., & 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.

NuGrid: Toward High Precision Double-Degenerate Merger Simulations with SPH in 3D (2008)
Presentation / Conference Contribution
(2008, July). NuGrid: Toward High Precision Double-Degenerate Merger Simulations with SPH in 3D. Presented at 10th Symposium on Nuclei in the Cosmos, Mackinac Island, Michigan, USA

We present preliminary results from recent high-resolution double-degenerate merger simulations with the Smooth Particle Hydrodynamics (SPH) technique. We put particular emphasis on verification and validation in our effort and show the importance of... Read More about NuGrid: Toward High Precision Double-Degenerate Merger Simulations with SPH in 3D.

Nucleosynthetic Yields from "Collapsars" (2008)
Presentation / Conference Contribution
(2008, July). Nucleosynthetic Yields from "Collapsars". Presented at 10th Symposium on Nuclei in the Cosmos, Mackinac Island, Michigan, USA

The "collapsar" engine for gamma-ray bursts invokes as its energy source the failure of a normal supernova and the formation of a black hole. Here we present the results of the first three-dimensional simulation of the collapse of a massive star down... Read More about Nucleosynthetic Yields from "Collapsars".

The impact of stellar rotation on the CNO abundance patterns in the Milky Way at low metallicities (2008)
Presentation / Conference Contribution
(2008, July). The impact of stellar rotation on the CNO abundance patterns in the Milky Way at low metallicities. Presented at 10th Symposium on Nuclei in the Cosmos, Mackinac Island, Michigan, USA

We investigate the effect of new stellar models, which take rotation into account, computed for very low metallicities on the chemical evolution of the earliest phases of the Milky Way. We check the impact of these new stellar yields on a model for t... Read More about The impact of stellar rotation on the CNO abundance patterns in the Milky Way at low metallicities.

Nucleosynthesis Calculations from Core-Collapse Supernovae (2008)
Presentation / Conference Contribution
(2008, July). Nucleosynthesis Calculations from Core-Collapse Supernovae. Presented at 10th Symposium on Nuclei in the Cosmos, Mackinac Island, Michigan, USA

We review some of the uncertainties in calculating nucleosynthetic yields, focusing on the explosion mechanism. Current yield calculations tend to either use a piston, energy injection, or enhancement of neutrino opacities to drive an explosion. We s... Read More about Nucleosynthesis Calculations from Core-Collapse Supernovae.

Complete nucleosynthesis calculations for low-mass stars from NuGrid (2008)
Presentation / Conference Contribution
(2008, July). Complete nucleosynthesis calculations for low-mass stars from NuGrid. Presented at 10th Symposium on Nuclei in the Cosmos, Mackinac Island, Michigan, USA

Many nucleosynthesis and mixing processes of low-mass stars as they evolve from the Main Sequence to the thermal-pulse Asymptotic Giant Branch phase (TP-AGB) are well understood (although of course important physics components, e.g. rotation, magneti... Read More about Complete nucleosynthesis calculations for low-mass stars from NuGrid.

Spatial Distribution of Nucleosynthesis Products in Cassiopeia A: Comparison Between Observations and 3D Explosion Models (2008)
Presentation / Conference Contribution
(2008, July). Spatial Distribution of Nucleosynthesis Products in Cassiopeia A: Comparison Between Observations and 3D Explosion Models. Presented at 10th Symposium on Nuclei in the Cosmos, Mackinac Island, Michigan, USA

We examine observed heavy element abundances in the Cassiopeia A supernova remnant as a constraint on the nature of the Cas A supernova. We compare bulk abundances from 1D and 3D explosion models and spatial distribution of elements in 3D models with... Read More about Spatial Distribution of Nucleosynthesis Products in Cassiopeia A: Comparison Between Observations and 3D Explosion Models.

Pushing the precision limit of ground-based eclipse photometry (2008)
Book Chapter
(2008). Pushing the precision limit of ground-based eclipse photometry. In Transiting Planets (IAU S253)

Until recently, it was considered by many that ground-based photometry could not reach the high cadence sub-mmag regime because of the presence of the atmosphere. Indeed, high frequency atmospheric noises (mainly scintillation) limit the precision th... Read More about Pushing the precision limit of ground-based eclipse photometry.

A survey for low mass spectroscopic binary stars in the young clusters around sigma Orionis and lambda Orionis (2008)
Journal Article
(2008). A survey for low mass spectroscopic binary stars in the young clusters around sigma Orionis and lambda Orionis. Monthly Notices of the Royal Astronomical Society, 2210-2224. https://doi.org/10.1111/j.1365-2966.2008.13008.x

We have obtained multi-epoch, high-resolution spectroscopy of 218 candidate low-mass stars and brown dwarfs in the young clusters around sigma Ori and lambda Ori. We find that 196 targets are cluster members based on their radial velocity, the equiva... Read More about A survey for low mass spectroscopic binary stars in the young clusters around sigma Orionis and lambda Orionis.

Disc-Magnetosphere interactions in Cataclysmic Variable Stars (2007)
Journal Article
(2007). Disc-Magnetosphere interactions in Cataclysmic Variable Stars. Proceedings of the International Astronomical Union, https://doi.org/10.1017/S1743921307009684

I review, from an observational perspective, the interactions of accretion discs with magnetic fields in cataclysmic variable stars. I start with systems where the accretion flows via a stream, and discuss the circumstances in which the stream forms... Read More about Disc-Magnetosphere interactions in Cataclysmic Variable Stars.

Developments in physics of massive stars (2007)
Presentation / Conference Contribution
Meynet, G., Ekström, S., Maeder, A., Hirschi, R., Georgy, C., & Beffa, C. Developments in physics of massive stars. Presented at Symposium S250: Massive Stars as Cosmic Engines

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.

The ultra-compact binary candidate KUV 23182+1007 is a bright quasar (2007)
Journal Article
Southworth, J., Schwope, A., Gaensicke, B., & Schreiber, M. (2007). The ultra-compact binary candidate KUV 23182+1007 is a bright quasar. arXiv,

KUV 23182+1007 was identified as a blue object in the Kiso UV Survey in the 1980s. Classification-dispersion spectroscopy showed a featureless continuum except for a strong emission line in the region of He II 4686 A. This is a hallmark of the rare A... Read More about The ultra-compact binary candidate KUV 23182+1007 is a bright quasar.

A new AMS facility in Caserta/Italy (2007)
Journal Article
(2007). A new AMS facility in Caserta/Italy. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 14 -17. https://doi.org/10.1016/j.nimb.2007.01.139

A new AMS system has been installed at Center for Isotopic Research on Cultural and Environmental Heritage (CIRCE) in Caserta/Italy. It was built by National Electrostatics Corp. Middleton, WI/USA, and arrived at CIRCE in the middle of January 2005;... Read More about A new AMS facility in Caserta/Italy.