I.—Earth-Movements,—Tremors and Pulsations

Neutron Star Pulsations and Instabilities

Gravitational radiation (GR) drives an instability in certain modes of rotating stars. This instability is strong enough in the case of the r-modes to cause their amplitudes to grow on a timescale of tens of seconds in rapidly rotating neutron stars. GR emitted by these modes removes angular momentum from the star at a rate which would spin it down to a relatively small angular velocity within ...

RADIATIVE OPACITIES AND STEllAR PULSATIONS

Pulsations in hot supergiants

Massive stars are the cosmic engines that shape and drive our Universe. Many issues such as their formation, their stability and the mass loss effects, are far from being completely understood. Recent ground-based and space observations have shown pulsations in massive MS and post-MS stars, such as acoustic and gravity modes excited by the κ-mechanism and even solar-like oscillations. Theoretic...

Lecture XXI: Radial pulsations and stability

Having constructed the equilibrium stellar configurations, we are now poised to ask whether they are stable to small perturbations. This leads us to the subject of relativistic stellar pulsations. One may classify such pulsations by their angular dependence: when we investigate the full subject we will find modes of every spherical harmonic index l ≥ 0. However, for the cold stars of interest t...

Radial pulsations and stability of protoneutron stars

Radial pulsations of newborn neutron stars (protoneutron stars) are studied for a range of internal temperatures and entropies per baryon predicted by the existing numerical simulations. Protoneutron star models are constructed using a realistic equation of state of hot dense matter, and under various assumptions concerning stellar interior (large trapped lepton number, zero trapped lepton numb...