Received ; accepted – 2 – ABSTRACT In this paper, we present a semi-empirical model of isolated binary star formation. This model includes the effects of turbulence in the initial state of the gas, and has binary orbital parameters consistent with observation. Our fundamental assumption is that the angular momenta of binary star systems is directly related to the net angular momentum induced by...

I discuss the nature of the compact X-ray source inside the supernova remnant RCW 103. Several models, based on the accretion onto a compact object such as a neutron star or a black hole (isolated or binary), are analyzed. I show that it is more likely that the X-ray source is an accreting neutron star than an accreting black hole. I also argue that models of a binary system with an old accreti...

Knowledge of the binary population in stellar groupings provides important information about the outcome of the star forming process in different environments (e.g., Blaauw 1991, and references therein). Binarity is also a key ingredient in stellar population studies, and is a prerequisite to calibrate the binary evolution channels. In this paper we present an overview of several commonly used ...

We propose a model for stellar binary systems consisting of a magnetic and a non-magnetic white-dwarf pair which is powered principally by electrical energy. In our model the luminosity is caused by resistive heating of the stellar atmospheres due to induced currents driven within the binary. This process is reminiscent of the Jupiter-Io system, but greatly increased in power because of the lar...

Abstract Population III (Pop. III) binary stars likely produced the first stellar-born black hole (BBH) mergers in Universe. Here, we quantify main sources of uncertainty for merger rate density evolution and mass spectrum Pop. BBHs by considering four different formation histories 11 models initial orbital properties stars. The on affects BBH up to two orders magnitude, with shorter periods le...

The parallaxes from Hipparcos are an important ingredient to derive more accurate masses for known orbital binaries. In order to exploit the parallaxes fully, the orbital elements have to be known to similar precision, and the present work is a rst survey of the orbital systems with parallax errors below about 5 per cent. With methods combining the inter-mediatèTransit Data' (published in the H...

There is at present no viable theory whereby a single star with MMS < 2.3 ± 0.3 M can sustain a PN-forming superwind with Ṁ > 3×10−5 M yr−1 at the tip of the AGB that can eject the last ∼0.3 M of envelope mass. We propose that a binary companion can not only result in non-spherical PN, but more importantly provide the AGB mass loss rate enhancement that is required to create a visible PN. We pr...

Given a sequence of positive integers p = (p1, . . . , pn), let Sp denote the family of all sequences of positive integers x = (x1, . . . , xn) such that xi ≤ pi for all i. Two families of sequences (or vectors), A,B ⊆ Sp, are said to be r-cross-intersecting if no matter how we select x ∈ A and y ∈ B, there are at least r distinct indices i such that xi = yi. We determine the maximum value of |...

Markwardt and Ögelman (1995) used ROSAT to reveal a 12 by 45 arcmin structure in 1 keV X rays around the Vela pulsar, which they interpret as a jet emanating from the pulsar. We here present an alternative view of the nature of this feature, namely that it consists of material from very deep inside the exploding star, close to the mass cut between material that became part of the neutron star a...