Browsing by Author "Belloni, D."

We present a systematic search for periodic X-ray sources in 10 Galactic globular clusters (GCs) utilizing deep archival Chandra observations. By applying the Gregory-Loredo algorithm, we detect 28 periodic signals among 27 independent X-ray sources in 6

Using archival Hubble Space Telescope observations, we report the discovery of four variable low-mass white dwarfs (WDs; 0.18 M circle dot <= M <= 0.5 M circle dot) in the globular cluster NGC 6397. One source exhibits a periodic optical modulation of 5.2

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 occultation of the

There could be a significant population of double white dwarf binaries (DWDs) inside globular clusters (GCs); however, these binaries are often too faint to be individually observed. We have utilized a large number GC models evolved with the Monte Carlo C

Context. Recent observations of close detached eclipsing M and K dwarf binaries have provided substantial support for magnetic saturation when stars rotate sufficiently fast, leading to a magnetic braking (MB) torque proportional to the spin of the star.A

Context. It has been claimed for more than a decade that energies other than orbital and thermodynamic internal are required to explain post-common envelope (CE) binaries with sufficiently long orbital periods (greater than or similar to 1 d) hosting AFGK

Context. The vast majority of close binaries containing a compact object, including the progenitors of supernovae Ia and at least a substantial fraction of all accreting black holes in the Galaxy, form through common-envelope (CE) evolution. Despite this

Context. Angular momentum loss through magnetic braking drives the spin-down of low-mass stars and the orbital evolution of a variety of close binary stars. Current theories for magnetic braking, often calibrated for one particular type of system, predict

We investigate whether the recently suggested rotation and crystallization driven dynamo can explain the apparent increase of magnetism in old metal polluted white dwarfs. We find that the effective temperature distribution of polluted magnetic white dwar

The origin of strong ((greater than or similar to) MG) magnetic fields in white dwarfs has been a puzzle for decades. Recently, a dynamo mechanism operating in rapidly rotating and crystallizing white dwarfs has been suggested to explain the occurrence ra

Context. The general prediction that more than half of all cataclysmic variables (CVs) have evolved past the period minimum is in strong disagreement with observational surveys, which show that the relative number of these objects is just a few percent.Ai

Based on the current detectable cataclysmic variable (CV) population in Galactic globular clusters (GCs), we show that there is not a clear relation between the number of sources per unit of mass and the stellar encounter rate, the cluster mass, or the cl

Context. The binary system SDSS J1257+5428 consists of an extremely low-mass white dwarf (WD) with a mass ranging from similar to 0.1 to similar to 0.24 M-circle dot, along with a more massive WD companion of approximately 1 M-circle dot that is significa

Context. AM CVn binaries are potential progenitors of thermonuclear supernovae and strong sources of persistent gravitational wave radiation. For a long time, it has been believed that these systems cannot descend from cataclysmic variables (CVs), at leas

Context. Magnetic wind braking drives the spin-down of low-mass stars and the evolution of most interacting binary stars. A magnetic braking prescription that was claimed to reproduce both the period distribution of cataclysmic variables (CVs) and the evo

Context. Recently, large and homogeneous samples of cataclysmic variables identified by the Sloan Digital Sky Survey (SDSS) were published. In these samples, the famous orbital period gap, which is a dearth of systems in the orbital period range similar t

Context. There are several symbiotic stars (e.g., BF Cyg, Z And, and FN Sgr) in which periodic signals of tens of minutes have been detected. These periods have been interpreted as the spin period of magnetic white dwarfs that accrete through a magnetic s

Context. Assuming that white dwarf (WD) magnetic fields are generated by a crystallization- and rotation-driven dynamo, the impact of the late appearance of WD magnetic fields in cataclysmic variables (CVs) has been shown to potentially solve several long

The origin of magnetic fields in white dwarfs remains a fundamental unresolved problem in stellar astrophysics. In particular, the very different fractions of strongly (more than about a megagauss) magnetic white dwarfs in evolutionarily linked population

The white dwarf (WD) binary SDSS J1257+5428 comprises an extremely low-mass WD with a mass of 0.1-0.24 M-circle dot and a more massive companion of similar to 1 M-circle dot that is more than 0.6 Gyr younger. The origin of this system has been termed para