The absence of a rigorous proof of the existence of dynamically stable, large-scale magnetic fields in radiative stars has been for many years a missing element in the fossil field theory for the magnetic Ap/Bp stars. Recent numerical simulations, by Braithwaite & Spruit and Braithwaite & Nordlund, have largely filled this gap, demonstrating convincingly that coherent global scale fields can su...

The possibility of trapped modes of gravitational waves appearing in stars with R > 3M is considered. It is shown that the restriction to R < 3M in previous studies of trapped modes, using uniform density models, is not essential. Scattering potentials are computed for another family of analytic stellar models showing the appearance of a deep potential well for one model with R > 3M . However, ...

In this lecture I review the theory of magnetized accretion discs driving jets, with a focus on Young Stellar Objects (YSOs). I first introduce observational and theoretical arguments in favor of the “disc wind” paradigm. There, accretion and ejection are interdependent, requiring therefore to revisit the standard picture of accretion discs. A simple magnetostatic approach is shown to already p...

Dark Stars are the very first phase of stellar evolution in the history of the universe: the first stars to form (at redshifts z ∼ 10 − 50) are powered by dark matter annihilation instead of fusion (if the dark matter is made of particles which are their own antipartners). We find equilibrium polytropic configurations for these stars; we start from the time DM heating becomes important (M ∼ 1 −...

Dark Stars are the very first phase of stellar evolution in the history of the universe: the first stars to form (at redshifts z ∼ 10 − 50) are powered by heating from dark matter (DM) annihilation instead of fusion (if the DM is made of particles which are their own antiparticles). We find equilibrium polytropic configurations for these stars; we start from the time DM heating becomes importan...

Abstract. Interacting galaxies like the famous Antennae (NGC 4038/4039) or Stephan’s Quintet (HCG 92) show considerable star forming activity in their tidal arms. High resolution images (e.g. from HST-observations) indicate that these regions consist of up to hundreds of massive stellar clusters or tidal dwarf galaxies (TDG). In this paper we want to investigate the future fate of these cluster...

Color–temperature relations and bolometric corrections in the HST–NICMOS F1110W, F160W and F222M and in the WFPC2 F439W, F555W and F814W photometric systems, using two different sets of model atmospheres, have been derived. This database of homogeneous, self–consistent transformations between the theoretical and observational planes also allows combinations of visual and infrared quantities, wi...

The work of J. A. Wheeler in the mid 1960’s showed that for smooth equations of state no stable stellar configurations with central densities above that corresponding to the limiting mass of ‘neutron stars’ (in the generic sense including hybrids) were stable. Accordingly, there has been no reason to expect that a stable degenerate family of stars with higher density than the known white dwarfs...

We investigate the collapse of nonrotating gas sp~eres with a polytropic.equ~tion of state.: n = 3, corresponding toy = 4/3. Such polytropes provide~ re~sonable approximatiOn t<? collapsmg stellar cores during the early phase before nuclear density IS reached. W~ find a.famtl~ of ~xact homologously collapsing configurations. Homologous collapse of the enti~e core Is possib~e If the pressure at ...

c JINR Dubna We have found correlations between properties of the equation of state for stellar matter with a phase transition at supernuclear densities and two characteristic features of a phase diagram for rotating compact stars in the angular velocity-baryon number plane: 1) the critical dividing line between mono-and two-phase star configurations and 2) the maximum mass line. The second lin...