Related papers: Observing the Accretion Stream in Polars
Hydrogen-line emission from an accretion shock has recently been observed at planetary-mass objects. Our previous work predicted the shock spectrum and luminosity for a shock on the circumplanetary disc. We extend this to the planet-surface…
The evolution of an accretion disk, formed as a consequence of the disruption of a star by a black hole, is followed by solving numerically the hydrodynamic equations. The present investigation aims to study the dependence of resulting…
Radiation of X-ray pulsars is powered by accretion on the neutron star surface from a binary companion under the influence of a strong magnetic field. We study beaming of this radiation in the case of subcritical X-ray pulsars, where it is…
We present an analysis of high-speed u- and r-band photometry of the eclipsing polar HU Aquarii that was obtained with ULTRACAM mounted on the VLT. The observations were performed during a low state, permitting us for the first time to…
Supercritical accretion flows inevitably produce radiation-pressure driven outflows, which will Compton up-scatter soft photons from the underlying accretion flow, thereby making hard emission. We perform two dimensional radiation…
Multi-epoch Chandra and XMM-Newton observations of the symbiotic system R Aquarii (R Aqr) spanning 22 yr are analysed by means of a reflection model produced by an accretion disc. This methodology helps dissecting the contribution from…
Nine metal-polluted white dwarfs are observed with medium-resolution optical spectroscopy,where photospheric abundances are determined and interpreted through comparison against solar system objects. An improved method of making such…
We present an analysis of mock X-ray spectra and light curves of magnetic cataclysmic variables using an upgraded version of the 3D CYCLOPS code. This 3D representation of the accretion flow allows us to properly model total and partial…
We present the combination of dynamical accretion model based on 3D GRMHD simulations and general relativistic (GR) polarized radiative transfer. We write down the formalism of and perform the GR ray-tracing of cyclo-synchrotron radiation…
Shape from Polarization (SfP) estimates surface normals using photos captured at different polarizer rotations. Fundamentally, the SfP model assumes that light is reflected either diffusely or specularly. However, this model is not valid…
Time-resolved photometry of the eclipsing polar CSS 081231:071126+44040 was obtained with the Vatican Advanced Technology Telescope (VATT) on four nights in October 2009. The light curve shows a single accretion hotspot lagging 10 degrees…
We present a low-resolution discovery spectrum and CCD-photometry of the bright X-ray source 1RXS J012851.9-233931 found in the ROSAT All-Sky Survey. These first observations suggest that the source is an AM Herculis star (polar) accreting…
Within the project Galactic Cold Cores we are carrying out Herschel photometric observations of cold interstellar clouds detected with the Planck satellite. The three fields observed as part of the Herschel science demonstration phase (SDP)…
The eclipsing low-mass X-ray binary 4U is the prototypical accretion disk corona (ADC) system. We have obtained new time-resolved UV spectrograms of 4U with the Hubble Space Telescope and new V- and J-band light curves with the 1.3-m SMARTS…
Thermal evolution of neutron stars is known to depend on the properties of superdense matter in neutron star cores. We suggest a statistical analysis of isolated cooling middle-aged neutron stars and old transiently accreting…
We compare the 230 GHz near-horizon emission from Sagittarius A* to simulations representing three classes of accretion flows. Using the structure function to capture the variability statistics of the light curve, we find a noticeable…
White dwarfs are the most common endpoints of stellar evolution. They are often found in close binary systems in which the white dwarf is accreting matter from a companion star, either via an accretion disc or channelled along the white…
Future telescopes will characterize rocky exoplanets in reflected light, revealing their albedo, which depends on surface, cloud, and atmospheric properties. Identifying these features is crucial for assessing habitability. We present…
The origin of the near-ultraviolet and optical continuum radiation in flares is critical for understanding particle acceleration and impulsive heating in stellar atmospheres. Radiative-hydrodynamic simulations in 1D have shown that high…
White dwarfs, the final evolutionary stage of the vast majority of stars, serve as critical tools for cosmochronology, studies of planetary system evolution, and laboratories for non-standard physics, including exotic cooling channels and…