H. Gulsecen

UBV Photometry of the Massive Eclipsing Binary TT Aur

UBV observations carried out mainly at the Turkish National Observatory (TUG) and the collected times of eclipse minima of the massive eclipsing binary TT Aur were used to study the system parameters. The simultaneous solution of the light curves by Wilson-Devinney (1992) code yields a semi-detached configuration with slightly larger Roche-lobe filling secondary. The shoulders of primary minimum indicate some excess absorption probably due to circumstellar material in the form of partial disk around the primary component. The deeper primary minimum in U filter can be an indication of a hotter region on the facing hemisphere of the primary. The period variation of the system reveals the existence of a possible third component star in a circular orbit around the system.

What's the Weather Like Today?: A computer game to develop algorithmic thinking and problem solving skills of primary school pupils

Computer-based games as developments in information technology seem to grow and spread rapidly. Using of these games by children and teenagers have increased. The presence of more beneficial and educational games in contrast to the violent and harmful games is remarkable. Many scientific studies have indicated that the useful (functional) games improve children’s cognitive capabilities. This paper examines the effect of a computer-based game developed as Weather Forecast Game on problem-solving abilities of children. The aim of this game design is to make children develop algorithms and create criteria by using simple visual and linguistic templates, and establish relationships between these criteria by making forecasts so that the pupils build forecast models related to game criteria by playing a game and have analytic information about everyday life weather events. At the development stage of this game, maximum importance was given to make it interesting and visual. Repetitive steps and instructions have been avoided. In this study, our guess is based on the research that whether this game brings reasoning, associating, communication and algorithmic thinking capacities to the children aged between “8–10” and if it does so, how it affects the problem-solving skills of them. An experiment was conducted with primary school pupils between ages of “8–10” to test their problem-solving capabilities. According to test measurements of ‘one group pre-test, post-test sample experiment method’, all group and paired test results (N = 45, Chi-Square = 143.149, p\le.05) show that Weather Forecast Game has 2.07 times positive effect on problem solving skills of children. The results of measurements before and after playing the Weather Forecast Game show that there is an increase in algorithmic thinking and problem-solving skills of pupils participating in this study.

Accretion Disk Winds in Dwarf Novae

It is well known that the International Ultraviolet Explorer observations of high-excitation P Cygni profiles of C IV and S IV lines provide direct evidence for winds in cataclysmic variables which reach speeds of ~5000 km s -1. We present in this paper our analysis of P Cygni profile for C IV line in seven dwarf novae based on 195 low-resolution IUE spectra. This work aims to do two things: i) to examine them in terms of wind properties, and ii) to seek time dependence of the lines indicating departure from axial symmetry in the outflow and/or disk and changes in the wind ionisation and/or mass loss rate. We infer the optical depth of C IV, the column density and the number density of absorbing and scattering ions in the region where the wind ionized.