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Ion-ion collisions at relativistic energies have been shown recently to be a promising technique for the production of hypernuclei. In this article, we further investigate the production of light $\Lambda$ hypernuclei by use of a hybrid…
Atmospheres having a significant radiative support are shown to be intrinsically unstable at luminosities above a critical fraction Gamma_crit ~ 0.5-0.85 of the Eddington limit, with the exact value depending on the boundary conditions. Two…
The lack of a high energy cutoff in the cosmic ray spectrum together with an apparently isotropic distribution of arrival directions for the highest energy events have strongly constrained most models proposed for the generation of these…
The origin of the highest-energy cosmic rays remains a mystery. The lack of a high energy cutoff in the cosmic ray spectrum together with an apparently isotropic distribution of arrival directions have strongly constrained most models…
The use of pressure to obtain new materials that can be recovered under ambient conditions is a central problem in high-pressure physics. Despite decades of research, this goal has only been achieved in the laboratory for a few notable…
The presence of inhomogeneities in a spatially unresolved source is often hard to establish. This limits the accuracy with which the source properties can be determined. It is shown how observed features not expected for a homogeneous model…
Jets are produced from hard scatterings in the early stages of heavy-ion collisions, therefore they can be exploited as probes for medium tomography. Such high-$p_T$ partons are expected to suffer energy loss in the hot and dense nuclear…
The surprising lack of a high energy cutoff in the cosmic ray spectrum at the highest energies together with an apparently isotropic distribution of arrival directions have strongly challenged most models proposed for the acceleration of…
CO spectral line formation in the Sun has long been a source of consternation for solar physicists, as have the elemental abundances it seems to imply. We modelled solar CO line formation using a realistic, ab initio, time-dependent 3D…
First attempts are made to derive astrophysical implications of the collision of clumped stellar winds from order of magnitude estimates and preliminary numerical simulations. Compared to colliding smooth winds, we find that the most…
The mass-loss rates from single massive stars are high enough to form radio photospheres at large distances from the stellar surface where the wind is optically thick to (thermal) free-free opacity. Here we calculate the far-infrared,…
Clusters of galaxies can potentially produce cosmic rays (CRs) up to very-high energies via large-scale shocks and turbulent acceleration. Due to their unique magnetic-field configuration, CRs with energy $\leq 10^{17}$ eV can be trapped…
Estimates of differential cross sections and longitudinal asymmetries are presented for the reactions $\bar pp\to \bar \Xi\Xi$ and $\bar pp\to \bar \Xi_c\Xi_c$ at energies $\sqrt{s}\lesssim 15$ GeV. The $\Xi$ and $\Xi_c$ hyperons are…
Cosmic rays with energies up to $10^{11}\,\mathrm{GeV}$ enter the atmosphere and produce showers of secondary particles. Inside these showers muons with high transverse momentum ($p_\mathrm{T} \gtrsim 2\,\mathrm{GeV}$) are produced from the…
The reddening properties and the star formation history of a sample of 19 starburst galaxies are investigated using multiwavelength spectroscopy and infrared broad band photometry. The difference in reddening between the ionized gas and the…
The currently available empirical evidence on the star formation processes in the extreme, high-pressure environments induced by galaxy encounters, mostly based on high-resolution Hubble Space Telescope imaging observations, strongly…
We examine in detail the recent proposal that extreme Cosmic-Ray-Dominated-Regions (CRDRs) characterize the ISM of galaxies during events of high-density star formation, fundamentally altering its initial conditions (Papadopoulos 2010).…
It has been suggested that cosmological gamma-ray bursts (GRBs) can produce the observed flux of cosmic rays at the highest energies. However, recent studies of GRBs indicate that their redshift distribution likely follows that of the…
Superbursts from accreting neutron stars probe nuclear reactions at extreme densities ($\rho \approx 10^{9}~g\,cm^{-3}$) and temperatures ($T>10^9~K$). These bursts ($\sim$1000 times more energetic than type I X-ray bursts) are most likely…
Terrestrial exoplanets likely form initial atmospheres through outgassing during and after accretion, although there is currently no first-principles understanding of how to connect a planet's bulk composition to its early atmospheric…