Mass X-Ray Binaries

Even stronger constraints are potentially available from the high-mass X-ray binary Vela X-l. This source contains a 20 M0 star, and radial velocity variations from the star have been measured as well as periodic timing variations from X-ray pulses. The orbital period is 8.96 days and the eccentricity of... 

Other constraints come from recent observations from X-ray satellites. Most robust seem the data from the low mass X-ray binary EXO 0478-676 obtained by Cottam et al. [37], From the redshifted absorption lines from ionized Fe and O a gravitational redshift z = 0.23 was deduced this gives rise to a mass-to-radius relation... 

Next we consider the compact star in the low mass X-ray binary 4U 1728-34. In a very recent paper Shaposhnikov et al. (2003) (hereafter STH) have analyzed a set of 26 Type-I X-ray bursts for this source. The data were collected by the Proportional Counter Array on board of the Rossi X-ray Timing Explorer (RXTE) satellite. For the interpretation of these observational data Shaposhnikov et al. 2003 used a model of the X-ray burst spectral formation developed by Titarchuk (1994) and Shaposhnikov Titarchuk (2002). Within this model, STH were able to extract very stringent constrain on the radius and the mass of the compact star in this bursting source. The radius and mass for 4U 1728-34, extracted by STH for different best-fits of the burst data, are depicted in Fig. 6 by the filled squares. Each of the four MR points is relative to a different value of the distance to the source (d = 4.0, 4.25, 4.50, 4.75 kpc, for the fit which produces the smallest values of the mass, up to the one which gives the largest mass). The error bars on each point represent the error contour for 90% confidence level. It has been pointed out (Bombaci 2003) that the semi-empirical MR relation for the compact star in 4U 1728-34 obtained by STH is not compatible with models pure hadronic stars, while it is consistent with strange stars or hybrid stars. 

Decisive informations on the mass-to-radius ratio can be provided by measuring the gravitational redshift of lines in the spectrum emitted from the compact star atmosphere. Very recently, redshifted spectral lines features have been reported for two different X-ray sources (Cottam et al. 2002 Sanwal et al. 2002). The first of these sources is the compact star in the low mass X-ray binary EXO 0748-676. Studying the spectra of 28 type-I X-ray bursts in... 

In this study we compare distribution of GRB galactocentric offsets with radial distributions of supernovae of types la and Ib/c, low mass and high mass X-ray binaries, and with models of dark matter (DM) halo density profile. We compare first and second moments of distributions and also their median values, moreover we apply visual technique for comparing a pair of empirical distributions — quantile-quantile plot. 

II) Mass Flow Binaries that are the products of internal evolutionary processes also include Novae and X-ray binaries that are thought to contain compact objects. Also, there is strong evidence that many, if not all, symbiotic stars are binaries. 

Binary molecular co-crystals of 2,5-bis(3-pyridyl)-l,3,4-oxadiazole and 2,5-bis-(4-pyridyl)-l,3,4-oxadiazole with benzene-1,3,5-tricarboxylic and benzene-1,2,4,5-tetracarboxylic acids were studied by X-ray and thermogravimetric analysis of mass loss <2005MI1247>. Dipole moments were used to study the flexoelectric effect in guest-host mixtures of 2,5-(4-pentylbenzene)-l,3,4-oxadiazole with commercial liquid crystal hosts <2005CM6354>. The luminescence properties of many other copolymers were also investigated (see Section 5.06.12.3). 

Iridium-rhodium alloys were prepared in electric arc furnace in argon atmosphere by smelting refined powders of rhodium and iridium of 99.95 mass% purity. The composition of the alloys was controlled by the atomic adsorption analysis using the Perkin-Elmer spectrophotometer with HUS-72 analyzer. X-ray phase analysis indicated that all binary systems had a single-phase FCC-structure characteristic of... 

Figure 15. Evolution of the mass transfer rate as function of time, for a binary consisting initially of a 1.8 M main sequence star and a 1 M white dwarf in a 0.7 d orbit. The line is drawn fully until the white dwarf reaches 1.4 M (star symbol). The calculation is continued assuming the compact star can accrete further (dotted part of the line cf. Langer et al. 2000). The first phase of high mass transfer rates may correspond to the supersoft X-ray sources. After its decay (t > 800 Myr), the system is CV-like only the beginning of this second phase of low mass transfer rates is shown.

Compounds of the type [(Me3Si)2N]3M have been prepared for all of the lanthanide elements except Pm, Tb, Dy, Tm, and Er (4). The synthetic method used in their preparation is nucleophilic substitution with three molar equivalents of lithium -or sodium - bis(trimethylsilyl)amide on the metal trichlorides in tetrahydrofuran. The compounds are rather high melting solids (145-170°C) which can be isolated by crystallization from pentane as long needles or by vacuum sublimation (80-100°C). The binary silylamides are monomeric in refluxing benzene solution, in the gas phase (by mass spectrometry), and in the solid state (by x-ray crystallography, see below). Thus, these compounds are three-coordinate, a unique coordination number for the lanthanide elements. 

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