Related papers: Non-linear pulsations in Wolf-Rayet stars
Context. Radiation-driven mass loss is key to our understanding of massive-star evolution. However, for low-luminosity O-type stars there are big discrepancies between theoretically predicted and empirically derived mass-loss rates (called…
In addition to coherent pulsation, many accreting neutron stars exhibit flaring activity and strong aperiodic variability on time scales similar to or shorter than their pulsation period. Such a behavior shows that the accretion flow in the…
The r-modes of neutron stars can be driven unstable by gravitational radiation. While linear perturbation theory predicts the existence of this instability, linear theory can't provide any information about the nonlinear development of the…
Given their strong stellar winds, Wolf-Rayet (WR) stars exhibit emission line spectra that are predominantly formed in expanding atmospheric layers. The description of the wind velocity field $v(r)$ is therefore a crucial ingredient in the…
Motivated by the nonlinear star formation efficiency found in recent numerical simulations by a number of workers, we perform high-resolution adaptive mesh refinement simulations of star formation in self-gravitating turbulently driven gas.…
We review potential mass-loss mechanisms in the various evolutionary stages of massive stars, from the well-known line-driven winds of O-stars and BA-supergiants to the less-understood winds from Red Supergiants. We discuss optically thick…
Context. Very massive clusters and regions of intense star formation such as the center of our Milky Way contain young, hydrogen-burning stars very close to the Eddington Limit. Formally classified as hydrogen-rich Wolf-Rayet stars, the…
We present new yields of 26Al from Wolf--Rayet stellar winds based on rotating stellar models which account well for numerous observed properties of massive stars. We study the impacts on the yields of a change of initial mass, metallicity…
Material accreted onto a neutron star can stably burn in steady state only when the accretion rate is high (typically super-Eddington) or if a large flux from the neutron star crust permeates the outer atmosphere. For such situations we…
The Wolf-Rayet star WR 46 is known to exhibit a very complex variability pattern on relatively short time scales of a few hours. Periodic but intermittent radial velocity shifts of optical lines as well as multiple photometric periods have…
Massive stars that become stripped of their hydrogen envelope through binary interaction or winds can be observed either as Wolf-Rayet stars, if they have optically thick winds, or as transparent-wind stripped-envelope stars. We approximate…
We investigate the influence of Wolf-Rayet (W-R) stars on their surrounding star-forming molecular clouds. We study five regions containing W-R stars in the inner Galactic plane ($l\sim$[14$^\circ$-52$^\circ$]), using multi-wavelength data…
High energy gamma-rays have been detected from Cygnus X-3, a system composed of a Wolf-Rayet star and a black hole or neutron star. The gamma-ray emission is linked to the radio emission from the jet launched in the system. The flux is…
We have carried out integral field unit (IFU) spectroscopy of H$\alpha$, [N II] and [O III] emission lines for a sample of Galactic planetary nebulae (PNe) with Wolf-Rayet (WR) stars and weak emission-line stars (wels). Comparing their…
Nonlinear radio waves modulate the plasma, scatter on the modulations, and develop an intermittent power spectrum -- perhaps. Rudiments of theory, numerical simulations, and qualitative modeling of nonlinear scattering are presented.…
Based on 1) a conjecture about the mean free path for particle scattering in perpendicular shock geometries, and 2) a model for Wolf Rayet star winds, we argue that explosions of Wolf Rayet stars can lead through diffusive particle…
Wolf-Rayet (WR) stars are the evolutionary phases of very massive stars prior to the final supernova explosion stage. These stars lose substantial mass during WN and WC stages. The mass losses are associated with diverse elemental and…
Most stars will experience episodes of substantial mass loss at some point in their lives. For very massive stars, mass loss dominates their evolution, although the mass loss rates are not known exactly, particularly once the star has left…
There exists both theoretical and observational evidence that the magnetic field decay in neutron stars may proceed in a pronounced non--linear way during a certain episode of the neutron star's life. In the presence of a strong magnetic…
We present the first high-resolution X-ray spectrum of a putatively single Wolf-Rayet star. 400 ks observations of WR 6 by the XMM-Newton-telescope resulted in a superb quality high-resolution X-ray spectrum. Spectral analysis reveals that…