相关论文: Tomography of Polars

Using an optical vortex coronagraph and simple adaptive optics techniques we have made the first convincing demonstration of an optical vortex coronagraph that is coupled to a star gazing telescope. In particular we suppressed by 97% the…

In the frame of the Solar System, the Doppler and aberration effects cause distortions in the form of mode couplings in the cosmic microwave background (CMB) temperature and polarization power spectra and hence impose biases on the…

Zeeman Doppler Imaging is a powerful tool for characterizing the strength and topology of stellar magnetic fields. In this research note, we present a new way to visualize the typical results from ZDI for an ensemble of stars, addressing…

We present our models of the effect of binaries on high-resolution spectroscopic surveys. We want to determine how many binary stars will be observed, whether unresolved binaries will contaminate measurements of chemical abundances, and how…

Black hole binaries exhibit a wide range of variability phenomena, from large-scale state changes to broadband noise and quasi-periodic oscillations, but the physical nature of much of this variability is poorly understood. We examine the…

We suggest a two-dimensional wavelet devised to deduce the large-scale structure of a physical field (e.g., the Galactic magnetic field) from its integrals along straight paths from irregularly spaced data points to a fixed interior point…

We have found the first convincing evidence for spiral structure in the accretion disc of a close binary. The eclipsing dwarf nova binary IP Peg, observed during the end phase of a rise to outburst, shows strong Balmer and Helium emission…

Magnetic Doppler imaging is currently the most powerful method of interpreting high-resolution spectropolarimetric observations of stars. This technique has revealed the presence of unexpected small-scale magnetic fields on the surfaces of…

We report on new simultaneous phase resolved spectroscopic and polarimetric observations of the polar (AM Herculis star) V834 Cen during a high state of accretion. Strong emission lines and high levels of variable circular and linear…

Pulsar timing is a promising technique for detecting low frequency sources of gravitational waves. Historically the focus has been on the detection of diffuse stochastic backgrounds, such as those formed from the superposition of weak…

Over the past decade, microlensing has developed into a powerful tool to study stellar astrophysics, especially stellar atmospheres, stellar masses, and binarity. I review this progress. Stellar atmospheres can be probed whenever the source…

Polarization is a degree of freedom of light carrying important information that is usually absent in intensity and spectral content. Imaging polarimetry is the process of determining the polarization state of light, either partially or…

The masses of stars including stellar remnants are almost exclusively known from binary systems. In this work, we study gravitational microlensing of faint background galaxies by isolated neutron stars (pulsars). We show that the resulting…

We have developed a 3D computer model of polars which includes the accretion stream, the accretion column, the secondary star, and the white dwarf. Each component is represented by a fine grid of surface elements. With brightness values…

Black holes in binary star systems are vital for understanding the process of pr oducing gravitational wave sources, understanding how supernovae work, and for p roviding fossil evidence for the high mass stars from earlier in the Universe.…

Disk-fed accretion onto neutron stars can power a wide range of astrophysical sources ranging from X-ray binaries, to accretion powered millisecond pulsars, ultra-luminous X-ray sources, and gamma-ray bursts. A crucial parameter controlling…

We explore an extended cosmological scenario where the dark matter is an admixture of cold and additional non-cold species. The mass and temperature of the non-cold dark matter particles are extracted from a number of cosmological…

The morphological properties of the outflowing circumstellar envelopes surrounding mass-losing stars in eccentric binary systems are presented from a set of three-dimensional hydrodynamical model simulations. Based on four template models…

The attracting properties of gravity enable matter present in cores to collapse into stars with seven orders of magnitude change in space and time making modelling of star formation a challenging multi-scale process. To circumvent this…

Stellar coronagraphs designed for high-contrast imaging of exoplanets inevitably introduce a small amount of instrumental polarization, called \emph{secondary polarization}. At the contrast levels required to detect and characterize…