Related papers: Blobs in Wolf-Rayet Winds: Random Photometric and …
The common - arguably ubiquitous - large-scale variability of optical and UV lines profiles of hot, massive stars is widely interpreted as the direct consequence of structured, variable winds. Many of the variability phenomena are observed…
Galactic dust emission is polarized at unexpectedly high levels, as revealed by Planck. The origin of the observed $\simeq 20\%$ polarization fractions can be identified by characterizing the properties of optical starlight polarization in…
Blue horizontal-branch stars are Population II objects which are burning helium in their core and possess a hydrogen-burning shell and radiative envelope. Because of their low rotational velocities, diffusion has been predicted to work in…
The processes of accretion of the gaseous blobs with different masses and densities onto strongly magnetized white dwarfs in the systems of polars have been modeled. We have proved that shot noise in blue wavelengths represents accretion of…
Stars with B[e] phenomenon comprise a very diverse group of objects in a different evolutionary status. These objects show common spectral characteristics, including presence of Balmer lines in emission, forbidden lines, and strong infrared…
New observations of 9 of the brightest northern O stars have been made with the Breger polarimeter on the 0.9~m telescope at McDonald Observatory and the AnyPol polarimeter on the 0.4~m telescope at Limber Observatory, using the…
Recent results for Galactic and Magellanic Cloud Wolf-Rayet stars are summarised based on line blanketed, clumped model atmospheres together with UV, optical and IR spectroscopy. The trend towards earlier WN and WC spectral types with…
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…
Be/X-ray binaries are the most numerous group of high-mass X-ray binaries. Their long-term optical and infrared variability reflects the evolution of the circumstellar disk around the luminous companion. This variability manifests…
We quantify the rapid variations in X-ray brightness ("flares") from the extremely massive colliding wind binary Eta Carinae seen during the past three orbital cycles by RXTE. The observed flares tend to be shorter in duration and more…
Infrared imaging of the colliding-wind binary Apep has revealed a spectacular dust plume with complicated internal dynamics that challenges standard colliding-wind binary physics. Such challenges can be potentially resolved if a…
The majority of Wolf-Rayet (WR) stars represent the stripped cores of evolved massive stars who lost most of their hydrogen envelope. In low metallicity environments, such as the Small Magellanic Cloud (SMC), stellar winds are weaker and…
Line-driven wind instability is expected to cause small-scale wind inhomogeneities, X-ray emission, and wind line profile variability. The instability can already develop around the sonic point if it is initiated close to the photosphere…
The majority of core-collapse supernova (CCSN) progenitors are massive stars in multiple systems, and their evolution and final fate are affected by interactions with their companions. These interactions can explain the presence of…
Stars stripped of their envelope through interaction in a binary are generally not considered when accounting for ionizing radiation from stellar populations, despite the expectation that stripped stars emit hard ionizing radiation, form…
We investigated the impact of selected cloud condensates in exoplanetary atmospheres on the polarization of scattered stellar radiation. We considered a selection of 25 cloud condensates that are expected to be present in extrasolar…
Stellar winds of massive stars are known to be driven by line absorption of UV photons, a mechanism which is prone to instabilities, causing the wind to be clumpy. The clumpy structure hampers wind mass-loss estimates, limiting our…
Observational evidence exists that winds of massive stars are clumped. Many massive star systems are known as non-thermal particle production sites, as indicated by their synchrotron emission in the radio band. As a consequence they are…
High-mass gamma-ray binaries are powerful nonthermal galactic sources, some of them hosting a pulsar whose relativistic wind interacts with a likely inhomogeneous stellar wind. So far, modeling these sources including stellar wind…
Light scattered off particles can become linearly polarized. Stars surrounded by oblique, co-rotating envelopes are therefore expected to manifest periodic linear polarimetric variations. The electron scattering magnetospheres of magnetic…