On The Period and 4860 Light Curve of Cygnus X-1.

Wide- and narrow-band photoelectric observations, including the H-beta and H-alpha line features, are given for Cyg X-1. The wide-band observations containing H-beta are compiled into a light curve that is distorted in phase and asymmetric in intensity. An analysis of this light curve, together with an appreciation of the uncertainty of its representation, is given. This analysis incorporates the spectroscopic mass ratio and orbital eccentricity and orientation and does not conflict with other known characteristics of the system. In addition, a phase-dependent variation of the Crawford beta index was found, with beta = 2.588 during the inferior conjunction of the unseen companion and with beta - 2.540 throughout the remainder of the orbital cycle. All light curves of the Cyg X-1 system have been scrutinized for epochs of maximum and minimum light, and these have been used to improve the orbital period. The improved period is consistent with the value derived from the radial velocities. There is a certain amount of evidence that the period for the first maximum of the light curve is longer than that for the other light extrema.

Main Author: Guinan, Edward F.
Other Authors: Dorren, J. David., Siah, M. Javad., Koch, Robert H.
Language: English
Published: 1978
Online Access: http://ezproxy.villanova.edu/login?url=https://digital.library.villanova.edu/Item/vudl:176544
Summary: Wide- and narrow-band photoelectric observations, including the H-beta and H-alpha line features, are given for Cyg X-1. The wide-band observations containing H-beta are compiled into a light curve that is distorted in phase and asymmetric in intensity. An analysis of this light curve, together with an appreciation of the uncertainty of its representation, is given. This analysis incorporates the spectroscopic mass ratio and orbital eccentricity and orientation and does not conflict with other known characteristics of the system. In addition, a phase-dependent variation of the Crawford beta index was found, with beta = 2.588 during the inferior conjunction of the unseen companion and with beta - 2.540 throughout the remainder of the orbital cycle. All light curves of the Cyg X-1 system have been scrutinized for epochs of maximum and minimum light, and these have been used to improve the orbital period. The improved period is consistent with the value derived from the radial velocities. There is a certain amount of evidence that the period for the first maximum of the light curve is longer than that for the other light extrema.