Observational manifestations of the change in the tilt of the accretion disk to the orbital plane in her X-1/HZ her with phase of its 35-day period

We analyze and interpret the RXTE/ASM X-ray light curves for the close binary system Her X-1/HZ Her obtained from February 1996 to September 2004. Some of the features found previously in the averaged X-ray light curves are confirmed by the new RXTE/ASM data. In particular, the anomalous dips and post-eclipse recoveries in two successive orbits in the short-on state are clearly distinguishable and are stable features of the X-ray light curves. We argue that to account for these features, the tilt of the accretion disk to the orbital plane must be assumed to change with phase of the 35-day period. We present a numerical model that can reproduce the observed features of the light curves.     

On Franck-Condon factors and intensity distributions in some band systems of I2, NS and PS molecules

Potential curves for theB andX states of I₂, NS and PS have been obtained by Rydberg-Klein-Rees (RKR) method. From these RKR potentials, Franck-Condon factors (FCFs) lot the above band systems have been calculated using the best available molecular constants, tested for accuracy on the electronic transition moment (ETM)-r-centroid curve in the case of I₂ and used in the study of observed abnormal intensity distribution in some bands of NS. A brief outline of the method used in the calculations of the FCFs is given.     

First locking of the Virgo central area interferometer with suspension hierarchical control

Operation of the central portion of Virgo as a simple 6 m Michelson interferometer has given the first demonstration of the possibility to control an interferometer suspended from Virgo full scale multistage seismic attenuators using information derived from the interferometer locking signal. A special role in the control is played by the first stage of these suspensions, an inverted pendulum: besides its seismic preisolation action, this stage has positioning dynamics of several mm, and it allows to exert a very low frequency control at the upper level of the suspension using the interferometer fringe signal. The application of this feedback to the top-stage of the suspension allows corrections of drifts, such as tidal ones, at a stage of the suspension where a large dynamic range in displacements is available, without introducing noise at the level of the mirror, resulting in a significant reduction of the lock keeping force applied directly on the mirror at the lowest stage of the attenuator.     

The impact of parameter lumping and geometric simplification in modelling runoff and erosion in the shrublands of southeast Arizona

There have been many studies of hydrologic processes and scale. However, some researchers have found that predictions from hydrologic models may not be improved by attempting to incorporate the understanding of these processes into hydrologic models. This paper quantifies the effect of simplifying watershed geometry and averaging the parameter values on simulations generated using the KINEROS2 model. Furthermore, it examines how these changes in model input effect model output. The model was applied on a small semiarid rangeland watershed in which runoff is generated by the infiltration excess mechanism. The study concludes that averaging input parameter values has little effect on runoff volume and peak in simulating runoff. However, geometric simplification does have an effect on runoff peak and volume, but it is not statistically significant. In contrast, both averaging input parameter values and geometric simplification have an effect on model‐predicted sediment yield. Copyright © 2005 John Wiley & Sons, Ltd.     

Eccentricities of Planets in Binary Systems

The most puzzling property of the extrasolar planets discovered by recent radial velocity surveys is their high orbital eccentricities, which are very difficult to explain within our current theoretical paradigm for planet formation. Current data reveal that at least 25% of these planets, including some with particularly high eccentricities, are orbiting a component of a binary star system. The presence of a distant companion can cause significant secular perturbations in the orbit of a planet. At high relative inclinations, large-amplitude, periodic eccentricity perturbations can occur. These are known as “Kozai cycles” and their amplitude is purely dependent on the relative orbital inclination. Assuming that every planet host star also has a (possibly unseen, e.g., substellar) distant companion, with reasonable distributions of orbital parameters and masses, we determine the resulting eccentricity distribution of planets and compare it to observations? We find that perturbations from a binary companion always appear to produce an excess of planets with both very high (?0.6) and very low (e ? 0.1) eccentricities. The paucity of near-circular orbits in the observed sample implies that at least one additional mechanism must be increasing eccentricities. On the other hand, the overproduction of very high eccentricities observed in our models could be combined with plausible circularization mechanisms (e.g., friction from residual gas) to create more planets with intermediate eccentricities (e? 0.1–0.6).