MODELS AND ASTROPHYSICAL PARAMETERS OF HIGH MASS X-RAY BINARIES

Abstract

ABSTRACT The objective of this work is the High Mass X-ray Binaries. These systems consist of a neutron star orbiting around a star of spectral type OB. According to the luminosity class of the optical companion they split into Supergiant X-ray binaries and Be/X-ray systems. In both systems the high energy radiation is due to the accretion phenomenum, but in the first case the accreted metter comes from the strong stellar wind of the primary and in the second case it comes from the circumstellar envelope surrounding the Be star equator. In this work I concentrate on the optical and infrared bands of the electromagnetic spectrum although a discussion of the X-ray characteristics for some systems is also done. The main results can be summarized as follows: 1. A tentative correlation between the maximum H-alpha equivalent width and the orbital period for Be/X-ray binary systems has been found. The neutron star appear to act as a barrier which prevents the formation of a big disk in systems with short orbital periods. 2. The EW(H-alpha) - EW(H-beta) diagram has been proved to be a good discriminator between Be/X-ray and Supergiant X-ray systems. We have used it to confirm the supergiant nature of 2S 0114+65 and AX 1845-04. 3. The correlation between the (J-K)0 and the equivalent width of the H-alpha line has been confirmed using simultaneous spectroscopic and photometric data. 4. Two empirical temperature calibrations in terms of the (b-y)0 and c0 indices were obtained, one to be applied to luminosity class II-V stars and the other to type I supergiants. These calibrations are the first empirical temperature calibrations in terms of the Stromgren photometric system for OB type stars. 5. The validity of the Fabregat & Reglero (1990) (MNRAS 247, 407) calibration was tested, and it is concluded that, as long as the c0 index is within the photometric standard relations (Perry et al 1987, PASP 99,1184), it provides values comparable to the existing photometric calibrations. 6. We have calculated the fundamental astrophysical parameters of a number of Be/X-ray systems by using photometric uvby calibrations. 7. The problem of the spectral and luminosity classification of LSI +65 degrees 010 (2S 0114 +650) was solved. By using intermediate and high resolution spectroscopy in the optical and infrared wavelengths bands and optical and infrared photometry we have classified it as a B1Ia with certainty. 8. The X-ray luminosity of LSI +65 degrees 010 has been explained in terms of the stellar wind model, by which matter expelled from the optical companion via a stellar wind is accreted onto the neutron star. 9. The monitoring of LSI +61 degrees 235 allowed us to detect an optical and infrared outburst. This outburst is explained as due to a growth in the size and density of the envelope surrounding the equator of the Be star. 10. The spectroscopic data revealed that LSI +61 degrees 235 shows considerable variability in the profile shape throughout the five years of observations. It completed a V/R cycle in approximately three years. They were explained assuming the existence of inflow-outflow radial fluxes of matter inside the circumstellar envelope.