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We review the longterm confusion which has existed over the nature of flaring in the brightest class of low mass X-ray binary: the Z-track sources, specifically in the Cygnus X-2 sub-group. Intensity reductions in the lightcurve produce a branch in colour -colour diagrams similar to that of real flares in the Sco X-1 like group, and the nature of this branch was not clear. However, based on observations of Cygnus X-2 in which this dipping/flaring occurred it was proposed that the mass accretion rate in Z-track sources in general increases monotonically along the Z-track towards the Flaring Branch, a standard assumption widely held. It was also suggested that the Cygnus X-2 group have high inclination. Based on recent multi-wavelength observations of Cygnus X-2 we resolve these issues, showing by spectral analysis that the Dipping Branch consists of absorption events in the outer disk, unrelated to the occasional real flaring in the source. Thus motivation for Mdot increasing along the Z from Horizontal - Normal to Flaring Branch is removed, as is the idea that high inclination distinguishes the Cygnus X-2 group. Finally, the observations provide further evidence for the extended nature of the Accretion Disk Corona (ADC), and the correct modelling of the ADC Comptonized emission is crucial to the interpretation of low mass X-ray binary data.
The brightest class of low mass X-ray binary source: the Z-track sources are reviewed specifically with regard to the nature of the three distinct states of the sources. A physical model is presented for the Cygnus X-2 sub-group in which increasing m
Based on the results of applying the extended ADC emission model for low mass X-ray binaries to three Z-track sources: GX340+0, GX5-1 and CygX-2, we propose an explanation of the CygnusX-2 like Z-track sources. The Normal Branch is dominated by the i
Optical and infrared interferometers definitively established that the photometric standard Vega (alpha Lyrae) is a rapidly rotating star viewed nearly pole-on. Recent independent spectroscopic analyses could not reconcile the inferred inclination an
This paper investigates the discrepancy between recent measurements of the density profile of the globular cluster 47 Tuc that have used HST data sets. Guhathakurta et al. (1992) used pre-refurbishment WFPC1 V-band images to derive r_c = 23 +/- 2. Ca
We present a new model for the Z-track phenomenon, based on analysis of the spectral evolution around the Z-track in several Z-track sources, in which radiation pressure plays a major role. Increasing mass accretion rate on the normal branch causes h