Related papers: The Critical Mass Ratio for W UMa-type Contact Bin…
A sample of 86 contact binary systems in 14 globular clusters with available color index data in (B-V) or in (V-I) has been analyzed. At least one third of all systems are numerous foreground Galactic Disk projections over long lines of…
While contact binary objects are common in the solar system, their formation mechanism is unclear. In this work we examine several contact binaries and calculate the necessary strength parameters that allow the two lobes to merge without…
The study of very short-period contact binaries provides an important laboratory in which the most important and problematic astrophysical processes of stellar evolution take place. Short-period contact systems, such as CC Com are…
Knowing the masses of the components of binary systems is very useful to constrain the possible scenarios that could lead to their existence. While it is sometimes possible to determine the mass of the primary star, for single-lined…
Binary stars and higher-order multiple systems are an ubiquitous outcome of star formation, especially as the system mass increases. The companion mass-ratio distribution is a unique probe into the conditions of the collapsing cloud core…
Because the majority of massive stars are born as members of close binary systems, populations of massive main-sequence stars contain stellar mergers and products of binary mass transfer. We simulate populations of massive stars accounting…
The lifetime of the remnant produced by the merger of two neutron stars can provide a wealth of information on the equation of state of nuclear matter and on the processes leading to the electromagnetic counterpart. Hence, it is essential…
Binary and multiple stellar systems are numerous in our solar neighborhood with 80 per cent of the solar-type stars being members of systems with high order multiplicity. The Contact Binaries Towards Merging (CoBiToM) Project is a programme…
Low mass ratio contact binary systems are more likely to have unstable orbits and potentially merge. In addition, such systems exhibit characteristics such as starspots and high energy emissions (UV) suggestive of chromospheric and magnetic…
W UMa-type contact binaries belong to close binary systems whose components exactly overflow their Roche lobes and share a common convective envelope (CCE). In the last twenty years, the long-term variations of their orbital periods have…
Studying compact-object binary mergers in star clusters is crucial for understanding stellar evolution and dynamical interactions in galaxies. Open clusters in particular are more abundant over cosmic time than globular clusters, however,…
We have attempted to establish an observational evidence for presence of distant companions which may have acquired and/or absorbed the angular momentum during evolution of multiple systems thus facilitating or enabling formation of contact…
We present archival HST and JWST ultraviolet through near infrared time series photometric observations of a massive minimal-contact binary candidate in the metal-poor galaxy WLM ($Z = 0.14 Z_{\odot}$). This discovery marks the lowest…
We present a study on low-mass contact binaries (LMCB) with orbital periods shorter than 0.3 days and total mass lower than about 1.4 solar mass. We show that such systems have a long pre-contact phase, which lasts for 8-9 Gyrs, while the…
Rapidly rotating stars are readily produced in binary systems. An accreting star in a binary system can be spun up by mass accretion and quickly approach the break-up limit. Mergers between two stars in a binary are expected to result in…
We develop a semi-analytic model to investigate how accretion onto wide low-mass binary stars can result in a close high-mass binary system. The key ingredient is to allow mass accretion while limiting the gain in angular momentum. We…
Recently, the LIGO-Virgo collaborations have reported the coalescence of a binary involving a black hole and a low-mass gap object (LMGO) with mass in the range $\sim2.5-5M_\odot$. Such detections, challenge our understanding of the black…
The recently discovered eclipsing binary system TYC 2675-663-1 is a X-ray source, and shows properties in the optical that are similar to the W UMa systems, but are somewhat unusual compared to what is seen in other contact binary systems.…
We present results from the first hydrodynamical star formation calculation to demonstrate that close binary stellar systems (separations $\lsim 10$ AU) need not be formed directly by fragmentation. Instead, a high frequency of close…
Stellar models of massive single stars are still plagued by major uncertainties. Testing and calibrating against observations is essential for their reliability. For this purpose one preferably uses observed stars that have never…