Related papers: A Second Kelvin-Helmholtz Timescale of Post Helium…
Light curves, explosion energies, and remnant masses are calculated for a grid of supernovae resulting from massive helium stars that have been evolved including mass loss. These presupernova stars should approximate the results of binary…
Two-dimensional hydrodynamical simulations of the deleptonization of a newly formed neutron star were performed. Driven by negative lepton fraction and entropy gradients, convection starts near the neutrinosphere about 20-30 ms after core…
We present the results from a series of two-dimensional core-collapse simulations using a rotating progenitor star. We find that the convection in these simulations is less vigorous because a) rotation weakens the core bounce which seeds…
Growing evidence suggests that the first generation of stars may have been quite massive (~100-300 M_sun). Could these stars have left a distinct nucleosynthetic signature? We explore the nucleosynthesis of helium cores in the mass range…
We investigate the observed depletion of red giants in the cores of post-core-collapse globular clusters. In particular, the evolutionary scenario we consider is a binary consisting of two low-mass stars which undergoes two common envelope…
We present a model for gamma-ray bursts (GRB's) in which a stellar mass black hole acquires a massive accretion disk by merging with the helium core of its red giant companion. The black hole enters the helium core after it, or its neutron…
Here we consider the strong evolution experienced by the matter reinserted by massive stars, both in giant star forming regions driven by a constant star formation rate, and in massive and coeval superstar clusters. In both cases we take…
We study turbulent convection during the core helium flash close to its peak by comparing the results of two and three-dimensional hydrodynamic simulations. We use a multidimensional Eulerian hydrodynamics code based on state-of-the-art…
Two-body relaxation times of nuclear star clusters are short enough that gravitational encounters should substantially affect their structure in 10 Gyr or less. In nuclear star clusters without massive black holes, dynamical evolution is a…
Ten years later, astronomers are still puzzled by the stellar evolution that produced SN 1987A --- a blue supergiant. In single star models, the new OPAL opacities make blue solutions more difficult to achieve, though still possible for…
A few percent of red giants are enriched in Lithium with $A(\mathrm{Li}) > 1.5$. Their evolutionary status has remained uncertain because these Li-rich giants can be placed both on the red-giant branch (RGB) near the bump luminosity and in…
Following work by W\"unsch and collaborators, we investigate a self-enrichment scenario for second generation star formation in globular clusters wherein wind material from first generation massive stars rapidly radiatively cools. Radiative…
There is growing observational evidence that gamma-ray bursts (GRBs) are powered by black holes accreting rapidly through a disk. The supernova-like outburst that accompanies some gamma-ray bursts suggest that some long-duration GRBs may be…
Helium star--compact object binaries, and helium star--neutron star binaries in particular, are widely believed to be the progenitors of the observed double neutron star systems. In these, the second neutron star is presumed to be the…
Blue-supergiant stars develop into core-collapse supernovae --- one of the most energetic outbursts in the universe --- when all nuclear burning fuel is exhausted in the stellar core. Previous attempts failed to explain observed explosions…
We study the possible existence of an electroweak star - a compact stellar-mass object whose central core temperature is higher than the electroweak symmetry restoration temperature. We found a solution to the Tolman-Oppenheimer-Volkoff…
The empirical laws of star formation suggest that galactic-scale gravity is involved, but they do not identify the actual triggering mechanisms for clusters in the final stages. Many other triggering processes satisfy the empirical laws…
It has been shown that proton ingestion episodes can happen in the formation of hot-subdwarf stars, and that neutron-capture processes are possible in those cases. Moreover, some helium-rich hot subdwarfs display extraordinarily high…
The formation of stars from gas drives the evolution of galaxies. Yet, it remains one of the hardest processes to understand when trying to connect observations of stellar and galaxy populations to models of large scale structure formation.…
The temperature distribution of field Li-rich red giants suggests the presence of a population of Li-rich red clump (RC) stars. One proposed explanation for this population is that all stars with masses near 2 $M_\odot$ experience a…