Related papers: The V471 Tauri System: A Multi-datatype Probe

A series of 353 red electronic spectra obtained between 1994 and 2010, and of 171 UBV photometric observations of the 2010 eclipse, were analyzed in an effort to better understand the eclipsing binary eps Aur. The main results follow. (1)…

We observed the post-common-envelope eclipsing binary with a white dwarf component, QS Vir, using the 1.88 m telescope of Kotammia Observatory in Egypt. The new observations were analyzed together with all multicolor light curves available…

Aims: Detect tertiary components of close binaries from spectroscopy and light curve modelling; investigate light-travel time effect and the possibility of magnetic activity cycles; measure mass-ratios for unstudied systems and derive…

A growing number of eclipsing binary systems of the "HW Vir" kind (i. e., composed by a subdwarf-B/O primary star and an M dwarf secondary) show variations in their orbital period, also called Eclipse Time Variations (ETVs). Their physical…

For three decades, adaptive optic surveys have revealed an excess of T Tauri binaries across a = 10-100 au in nearby star-forming regions compared to the field population of main-sequence (MS) stars. Such an excess requires that most stars…

We present initial results from a Hubble Space Telescope ultraviolet imaging survey of stars known to have hot white-dwarf companions which are unresolved from the ground. The hot companions, discovered through their EUV or UV emission, are…

We present first results of a survey for companions among X-ray selected pre-main sequence stars, most of them being weak-line T Tauri stars (WTTS). These T Tauri stars have been identified in the course of optical follow-up observations of…

With the prevalence of wide-field, time-domain photometric sky surveys, the number of eclipsing white dwarf systems being discovered is increasing dramatically. An efficient method to follow these up will be key to determining any…

Context. In multiple pre-main-sequence systems the lifetime of circumstellar disks appears to be shorter than around single stars, and the actual dissipation process may depend on the binary parameters of the systems. Aims. We report high…

Up to now, most planet search projects have concentrated on F to K stars. In order to considerably widen the view, we have stated a survey for planets of old, nearby brown dwarfs and very low mass stars. Using UVES, we have observed 26…

The orbits and physical parameters of three close, double-lined G0 eclipsing binaries have been derived combining H_P, V_T, B_T photometry from the Hipparcos/Tycho mission with 8480-8740 \AA ground-based spectroscopy. The setup is mimicking…

A new relative orbit solution with new dynamical masses is determined for the nearby white dwarf - red dwarf pair 40 Eri BC. The period is 230.09+/-0.68y. It is predicted to close slowly over the next half-century getting as close as 1.32"…

We have discovered T Tauri stars which show startling spectral variability between observations seperated by 20 years. In spectra published by Bouvier & Appenzeller (1992) these objects showed very weak H-alpha emission, broad CaII…

We report observations of the known cataclysmic variable star (CV) V704 And, and also confirm that the optical counterpart of the ROSAT Galactic Plane Survey source RX J2338+431 is a heretofore-neglected CV. Photometric and spectroscopic…

Gaia DR3 mission has identified and provided about 440,000 binary systems with orbital solutions, offering a valuable resource for searching binaries including a compact component. By combining the Gaia DR3 data with radial velocities (RVs)…

Hot subdwarf B stars (sdBs) are evolved, core helium-burning objects located on the extreme horizontal branch. Their formation history is still puzzling as the sdB progenitors must lose nearly all of their hydrogen envelope during the…

Aims: Our goal was to increase number of known doubly eclipsing systems such that the resulting dataset would allow to study them via statistical means, as well as prove that they constitute gravitationally bound 2+2 quadruple system.…

V1022 Cas has been known as a spectroscopic binary for a century. It was found to be eclipsing based on photometry from the Hipparcos satellite, and an astrometric orbit was recently obtained from near-infrared interferometry. We present…

We survey our understanding of classical novae: non-terminal, thermonuclear eruptions on the surfaces of white dwarfs in binary systems. The recent and unexpected discovery of GeV gamma-rays from Galactic novae has highlighted the…

We present spectra for 33 previously unclassified white dwarf systems brighter than V = 17 primarily in the southern hemisphere. Of these new systems, 26 are DA, 4 are DC, 2 are DZ, and 1 is DQ. We suspect three of these systems are…