Related papers: Oscillations in the stable starless core Barnard 6…

We study the time evolution of spherical, excited -- with $n$ radial nodes -- scalar boson stars in General Relativity minimally coupled to a complex massive scalar field with quartic self-interactions. We report that these stars, with up…

We investigate the Hierarchical Gravitational Fragmentation scenario through numerical simulations of the prestellar stages of the collapse of a marginally gravitationally unstable isothermal sphere immersed in a strongly gravitationally…

We present a near-infrared extinction study of the dark globule L694-2, a starless core that shows strong evidence for inward motions in molecular line profiles. The J,H, and K band data were taken using the European Southern Observatory…

In a previous paper (Voglis et al. 2006a, paper I) we demonstrated that, in a rotating galaxy with a strong bar, the unstable asymptotic manifolds of the short period family of unstable periodic orbits around the Lagrangian points L$_1$ or…

A thin gaseous disc with an almost keplerian angular velocity profile, bounded by a free surface and rotating around point-mass gravitating object is nearly spectrally stable. Despite that the substantial transient growth of linear…

In this work we consider the evolution of a massive scalar field in cylindrically symmetric space-times. Quasinormal modes have been calculated for static and rotating cosmic cylinders. We found unstable modes in some cases. Rotating as…

Scalar, spherically symmetric, radially excited boson stars were previously shown to be stabilized, against spherical dynamics, by sufficiently strong self-interactions. Here, we further test their stability now in a full 3+1D evolution. We…

The buckling process in stellar bars is full of unsolved issues. We analyze the origin of the buckling instability in stellar bars using high-resolution N-body simulations. Previous studies have promoted the nonresonant firehose instability…

We study a modified Bullard dynamo and show that this system is equivalent to a nonlinear oscillator subject to a multiplicative noise. The stability analysis of this oscillator is performed. Two bifurcations are identified, first towards…

The search for the onset of star formation in pre-stellar cores has focussed on the identification of an infall signature in the molecular line profiles of tracer species. The classic infall signature is a double peaked line profile with an…

Acoustic oscillations in stars are sensitive to stellar interiors. Frequency differences between overtone modes -- large separations -- probe stellar density, while differences between low-degree modes -- small separations -- probe the…

We present the results of the first detailed millimeter and submillimeter molecular line survey of bright rimmed clouds, observed at FCRAO in the CO (J=1-0), C18O (J=1-0), HCO+ (J=1-0), H13CO+ (J=1-0), and N2H+ (J=1-0) transitions, and at…

Cold cores in interstellar molecular clouds represent the very first phase in star formation. The physical conditions of these objects are studied in order to understand how molecular clouds evolve and how stellar masses are determined. The…

Molecular gas disks are generally Toomre stable ($Q_T>$1) and yet clearly gravitationally unstable to structure formation as evidenced by the existence of molecular clouds and ongoing star formation. This paper adopts a 3D perspective to…

We present idealized models of a razor-thin, axisymmetric, Keplerian stellar disc around a massive black hole, and study non-axisymmetric secular instabilities in the absence of either counter-rotation or loss cones. These discs are…

We identify an intriguing feature of the electron-vibrational dynamics of molecular systems via a computational examination of \emph{trans}-polyacetylene oligomers. Here, via the vibronic interactions, the decay of an electron in the…

I examine the stability of retrograde mixed modes in rotating B-type stars. These modes can be regarded as a hybrid between the Rossby modes that arise from conservation of vorticity, and the Poincare modes that are gravity waves modified…

We study the possibility for an observational detection of oscillations due to baryons in the matter power spectrum and suggest a new cosmological test using the angular power spectrum of halos. The "standard rulers" of the proposed test…

Massive stars are important building blocks of the Universe, and their stellar structure and evolution models are fundamental cornerstones of various fields in modern astrophysics. The precision of these models is limited by our lack of…

Rotation is expected to have an important influence on the structure and the evolution of stars. However, the mechanisms of angular momentum transport in stars remain theoretically uncertain and very complex to take into account in stellar…