Time variation of the X-ray spectrum and optical luminosity of SCO X-1

Abstract

Results of rocket observations of SCO X-1 over the spectral range of 2∼20 keV are presented. The observations have been performed partly in India and partly in Japan under the collaboration of the three groups. The present results are compared with results of similar observations carried out by the LRL (Lawrence Radiation Laboratory) group. Some of these X-ray observations were accompanied by simultaneous optical observations. Relationships between the hardness of the X-ray spectrum and the X-ray intensity and between the hardness and the optical luminosity are compiled. The relationships among the parameters (temperature, density and size) which characterize the postulated isothermal cloud model of SCO X-1 are given. They indicate that SCO X-1 is characterized by a temperature of about 10⁷-10⁸K, a density of about 10¹⁶-10¹⁷ cm⁻³ and a radius of about 10⁸-10⁹ cm respectively. We further show that the temperature is inversely correlated with the size of the source; an increase in temperature corresponds to a decrease in the radius and an increase in density.