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

Sco X-1

“…They found that in X-ray flare the flux at 6-12 keV increased relative to the flux at 3-6 keV. Assuming the free-free spectrum Kitamura et al (1971) compiled the change of the apparent temperature relative to the X-ray emission measure by using the published data including Vela 5 observation, which is shown in Figure 15(a). It is seen that in flare state the apparent temperature often increases up to about 30 keV and the emission measure increases by a factor of 2-3.…”

“…and X-ray (3-12 keV) observations were made with Vela 5 satellite during optical flares (Evans et al, 1970), and the data showed that at the flare the apparent temperature (kT) increased up to about 20-30 keV, and the emission measure of the X-rays increased by factor of 2-3 (Kitamura et al, 1971).…”

“…One is a hot (T-5 x 107K) plasma model, self-absorbing in the optical and lower frequency regions by the plasma itself which emits both the observed X-rays and the continuum optical flux (Chodil, 1968;Neugebauer et al, 1969;Kitamura et al, 1971;Hayakawa et al, 1974). The other is a model attributing to other emitters from which the large fraction of the optical radiations comes besides the X-ray emitting plasma (Katz, 1975;Milgrom, 1976), which includes the heating model of the primary star by X-rays.…”

“…The distance of Sco X-1 has been estimated by various method (Westphal et al, 1968;Hiltner and Mook, 1970;Felten and Humphreys, 1973;Oda and Matsuoka, 1971), but it has not been well established.…”

“…Kitamura et al (1971) also performed the simultaneous observation at optical and X-ray wave lengths and compiled relationships between the hardness of the X-ray spectrum and the X-ray intensity, and between the X-ray and the optical luminosity.…”