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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Spectroscopic observations of the Cygnus X-1 optical candidate.

Data from nine high-dispersion spectra of HDE 226868, the optical candidate for Cyg X-1, are presented. The line profiles at He II (4686 A) show marked changes from night to night. Our data are not compatible with models where the emission line arises from the unseen secondary component of the system, as has been suggested by other observers. We propose that the emission originates in a gas stream falling toward the secondary; this provides observational evidence that the X-ray source is powered by accretion. We also see changes in spectral type and luminosity class with phase, further complicating attempts to make mass estimates for the system.

Smith, H. E.↗
NASA NTRS1973

Spectroscopic observations of the optical candidate for Cygnus X-1.

The spectroscopic binary BD+34 3815 (= HDE 226868) with a period of 5.6 days, which is the brightest object in the position box for the X-ray source Cyg X-1, is studied to determine whether it meets all the requirements for being a black hole. Evidence is presented that the mass of the secondary is larger than the upper limits for white dwarfs or neutron stars, but there is no conclusive evidence that the optical binary is an X-ray source, and that the secondary is a collapsed object.

Brucato, R.↗
NASA NTRS1974

The nature of Cygnus X-3 - A prototype for old population binary X-ray sources

Description of a model for Cyg X-3 based on a short-lived phase in the evolution of a U Geminorum-type binary where rapid mass transfer and mass loss occurs. X rays are generated by accretion on the white dwarf component, while both stars are enveloped in a thick stellar wind emanating from the red dwarf. Electron scattering in the cloud is responsible for the modulation of the X rays with the orbital period of 4.8 hours. Ultraviolet radiation and low-energy X rays absorbed in the cloud are reradiated in the optical and infrared, which, it is predicted, will display a 4.8-hr modulation in phase with the X-ray light curve. The X-ray absorption cutoff should also vary with phase, appearing at minimum energy when the source is at maximum light. The model also provides a framework in which certain aspects of the associated nonthermal radio source may be understood. Finally, it is suggested that the model may be applicable to Sco X-1 as well.

Davidsen, A.↗
NASA NTRS1974

Observations of the 4.8-hour variations of Cygnus X-3 above 7 keV from the OSO-7

Results of observations made (during the period from June 30 to July 5, 1972) of Cyg X-3 with the UCSD OSO-7 X-ray telescope in the range from about 7 to 100 keV. The 4.8-hour variation was detected in the 6.6-21.2 keV range, and the ratio of high intensity to mean intensity was 1.52 plus or minus 0.16. In the 21.2-97.8 keV range no 4.8-hour variation in phase with the 6.6-21.2 keV variation could be detected, and the ratio at the phase of high intensity to the mean intensity was 0.6 plus or minus 0.4.

Ulmer, M. P.↗
NASA NTRS1974

Infrared, radio, and X-ray observations of Cygnus X-3

Infrared observations of Cyg X-3 are presented along with X-ray and radio data. A study of the data shows evidence for several types of behavior in the infrared flux variations of Cyg X-3. It is pointed out that a lack of periodic variations observed can be due either to a real absence of these variations or to a masking by an outburst preceding the observation time. There is no simple radio-infrared correlation, although both radio and infrared emissions were observed during the same period of time.

Becklin, E. E.↗