Related papers: Optical and X-ray Transients from Planet-Star Merg…
Many giant exoplanets are found near their Roche limit and in mildly eccentric orbits. In this study we examine the fate of such planets through Roche-lobe overflow as a function of the physical properties of the binary components,…
Unstable mass transfer may occur during white dwarf-neutron star (WD-NS) mergers, in which the WD can be tidally disrupted and form an accretion disk around the NS. Such an accretion disk can produce unbound wind ejecta, with synthesized…
The problem of disk accretion onto the surface of a neutron star with a weak magnetic field at a luminosity exceeding several percent of Eddington is reduced to the problem of the braking of a hypersonic flow with a velocity that is 0.4-0.5…
Galaxy mergers are predicted to trigger accretion onto the central supermassive black holes, with the highest rates occurring during final coalescence. Previously, we have shown elevated rates of both optical and mid-IR selected active…
We study mass transfer by Roche lobe overflow in close-in exoplanetary systems. The planet's atmospheric gas passes through the inner Lagrangian point and flows along a narrow stream, accelerating to 100-$200\kms$ velocity before forming an…
We find a strong correlation between the optical outburst amplitude Delta V and orbital period P_{orb} for the soft X-ray transient sources with orbital periods less than 1 day. By fitting the observed values for 8 X-ray transients we…
Several evolutionary sequences with low--mass secondaries ($M_d $=1.25, 1.5 and 1.7$ M_\odot $) and black hole accretors ($M_{bh} $=5 and 10$ M_\odot$) are calculated. The angular momentum losses due to magnetic braking and gravitational…
We report the results of our campaign to follow-up spectroscopically several candidate extrasolar transiting planets from the OGLE-III survey in the direction of the Galactic center, announced in 2001 (Udalski et al 2002a,b). All of these…
Planets that reside close-in to their host star are subject to intense high-energy irradiation. Extreme-ultraviolet (EUV) and X-ray radiation (together, XUV) is thought to drive mass loss from planets with volatile envelopes. We present…
We find transient, transit-like dimming events within the K2 time series photometry of the young star RIK-210 in the Upper Scorpius OB association. These dimming events are variable in depth, duration, and morphology. High spatial…
We explore the multi-messenger signatures of encounters between two neutron stars and between a neutron star and a stellar-mass black hole. We focus on the differences between gravitational wave driven binary mergers and dynamical…
The majority of massive stars reside in binary systems, which are expected to experience mass transfer during their evolution. However, so far the conditions under which mass transfer leads to a common envelope, and thus possibly to a…
Most black holes (BHs) formed in collapsing stars have low spin, though some are expected to acquire a magnetic accretion disk during the collapse. While such BH disks can launch magnetically driven winds, their physics and observational…
Planetary transits are commonly observed at visible wavelengths. Here we investigate the shape of a planetary transit observed at radio wavelengths. Solar maps of the Sun at 17 GHz are used as a proxy for the stellar eclipse by several…
When a planet transits in front of its host star, a fraction of its light is blocked, decreasing the observed flux from the star. The same is expected to occur when observing the stellar radio flux. However, at radio wavelengths, the planet…
Collapsing massive stars lead to a broad range of astrophysical transients, whose multi-wavelength emission is powered by a variety of processes including radioactive decay, activity of the central engine, and interaction of the outflows…
We study the expected X-ray luminosity of stellar merger products several years after merger. The X-ray emission is assumed to result from magnetic activity. The extended envelope of the merger product possesses a large convective region…
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst…
Wide-field survery have recently detected recurring optical and X-ray sources near galactic nuclei, with period spanning hours to years. These phenomena could result from repeated partial tidal disruptions of stars by supermassive black…
Tidal disruptions of stars by stellar-mass black holes are expected to occur frequently in dense star clusters. Building upon previous studies that performed hydrodynamic simulations of these encounters, we explore the formation and…